Anatomy Flashcards

Question

Brachial plexus terminal branches and innervation

Answer 1

Musculocutaneous - Skin of anterolateral forearm - Brachialis, biceps brachii, coracobrachialis Axillary - skin of lateral portion of shoulder+upper arm - Deltoid and teres minor Radial - Posterior aspect of lateral forearm and wrist+post. Arm - triceps brachii, brachioradialis, anconeus, extensor muscles of post. Arm and forearm Median - skin of lateral 2/3rd of hand+tips of digits 1-4 - forearm flexors, thenar eminence, lumbricals of hand 1-2 Ulnar - skin of palm and medial hand+ digits 3-5 - hypothenar eminence, some forearm flexors, thumb adductor, lumbricals 3-4 and interosseous muscles

Answer 2

``` 'Some Irish People Came Traveling Quickly On Perfect Paper Planes Laughing Proudly': Superior gluteal nerve Inferior gluteal nerve Nerve to Piriformis muscle Common fibular division of sciatic nerve Tibial division of sciatic nerve Nerve to Quadratus femoris Nerve to Obturator internus Posterior cutaneous nerve of thigh Perforating cutaneous nerve Pudendal nerve Nerve to Levator ani Perineal branch of S4 ```

Answer 3

``` 6Ps Nerve to Piriformis Posterior cutaneous nerve of thigh Perforating cutaneous nerve Pudendal nerve Perineal branch of the 4th sacral nerve Pelvic sphlancnic nerves Major branches SIPPS: S – Superior gluteal nerve (nerve to quadratus femoris/inferior gemellus may be associated here since they share nerve roots) I – Inferior gluteal nerve (nerve to obturator internus/superior gemellus may be associated here since they share nerve roots) P – Posterior cutaneous nerve of thigh P – Pudendal nerve S – Sciatic nerve ```

Answer 4

C5 and C6 roots join - branch dorsal scapula nerve and contribute to long thoracic - superior trunk branches subclavian and suprascapula nerves- anterior superior division branch posterior superior nerve to join posterior middle division - lateral cord branches lateral pectoral nerve - musculocutaneous nerve terminates branch contributes to median nerve with C8 and T1 C7 root contributes to long thoracic nerve - middle trunk no branches - posterior middle division sends anterior middle branch to join anterior superior division and joined by posterior superior and inferior from superior and inferior divisions respectively - posterior cord branches upper subscapular, thoracodorsal and lower subscapular nerves - radial nerve branches auxiliary C8 and T1 join - inferior trunk - anterior inferior division branches posterior inferior branch to posterior middle division- medial cord branches medial brachial cutaneous, medial pectoral and medial anterior brachial cutaneous - branch contribute to median nerve with C5 and 6 and terminates in ulnar nerve

Answer 5

CO X Total Peripheral Resistance (TPR)

Answer 6

C5+6 - dorsal scapular nerve, contribute to long thoracic, suprescapular nerve and nerve to subclavian, branch to join posterior trunk, lateral pectoral, branch to join median nerve, terminates as musculocutaneous DLSSPLMM - dont leave small smelly pubes lying mindlessly marooned C7 - contributes to long thoracic nerve, branch to join anterior trunk, upper and lower subscapular branches, thoracodorsal, axillary branch and terminates as radial nerve TAULTAR - lets get married at T'AULTAR (northern accent) C8+T1 - T1 first intercostal nerve, branch to join posterior trunk, medial pectorial, medial cutaneous branches to forearm(C8) and arm(T1), contributes to median nerve, terminates as ulnar nerve IPMMMU - If peeing might make much urine

Answer 7

``` Activation of sympathetic system Activation of renin-angiotensin system Natriuretic peptides (BNP) Ventricular dilation Ventricular remodelling ```

Answer 8

Improves ventricular function by increasing HR and myocardial contractility Does this by constricting veins, increasing venous return (preload) Also, leads to constriction of arteries, increasing BP, increasing afterload; reducing SV and therefore CO

Answer 9

Fall in CO and increased sympathetic tone detected by decreased renal perfusion in kidneys leads to activation Increases salt and water retention and increases venous pressure (preload) maintaining SV and CO As this retention increases, peripheral and pulmonary congestion occurs (oedema and dyspnoea) Angiotensin also leads to arteriolar constriction; increasing BP (afterload); decreasing SV and CO

Answer 10

Released from ventricles; diuretic, natriuretic, hypotensive hormones help reduce pre and afterload But this is inadequate long term

Answer 11

Myocardial failure leads to reduced SV and increased blood remaining in ventricles after systole. This stretches myocardial fibres and restores myocardial contraction Once HF is established, heart is not able to compensate enough via this method Causes peripheral and pulmonary oedema

Answer 12

Hypertrophy; loss of myocytes and increases fibrosis | Progressive and irreversible contractile failure occurs from this

Answer 13

heart failure begins with depressed ejection fraction (EF) Begins after index event like MI, producing initial decline in pumping capacity After this, compensatory mechanisms are activated In the short term these systems restore CO and cardiac function to normal range and patient is asymptomatic With sustained activation of these systems can lead to secondary end-organ damage within the ventricle, remodelling of LV occurs and subsequent cardiac decompensation. Patient becomes symptomatic

Answer 14

Upper - nasal cavity, pharynx and larynx | Lower - trachea, primary bronchi and lungs

Answer 15

Sternal angle, or Angle of Louis, is a palpable clinical landmark in surface anatomy. Junction line of manubrium and body of the sternum. 2nd ribs attach the sternum at this level. Trachea also bifurcates at this level/imaginary plate. Apex of scapula: 7th ICS space usually Apex of axilla: Gently separate the arm from the thorax for a few cm. Push hand into axilla space can reach 2nd ICS

Answer 16

ICS vein, artery and nerve (VAN) are found anterior to innermost ICS and posterior to Internal ICS directly inferior to superior rib in the intercostal groove Clinical relevance; approach from upper margin to avoid VAN bundle, except in nerve block

Answer 17

12 pairs: 7 true, 1-7; attach directly to the sternum 3 False, 8-10; attach to the rib above 2 floating, 11-12; only attached to the spine with no anterior attachment (protect the kidneys posteriorly) Intercostal muscles: Three layers; external, internal and innermost intercostal muscles External: elevates ribs during forced inspiration Internal: depresses ribs during forced expiration Innermost: depresses ribs in forced expiration Intercostals of each hemithorax act as one muscle: if one point is painful, then half the thorax will reduce movement

Answer 18

Main functions: Gaseous exchange Anatomy: Right lung divided into 3 lobes; left is 2 Trachea divides at the carina (at sternomanubrial junction) into right and left main bronchi. Right is steeper (clinical relevance to aspiration). Branch into secondary, tertiary bronchi, bronchioles then into terminal bronchioles and finally alveoli Lungs enclosed with visceral and parietal pleura (join at hilum) Interpleural space has small amount of lubricating fluid for movement Alveolar pneumocytes - type I; 95-97% total surface area of lungs, where gaseous exchange occurs. Type II; secrete pulmonary surfactant and reabsorb sodium and water, preventing fluid buildup. Macrophages; remove pathogens in lungs. Mucocillary clearance - Mucous membranes in our respiratory tract trap airborne pollutants and tiny cilia transport them to our pharynx, where they are swallowed or coughed out Airways lined with ciliated columnar cells and goblet cells (mucus producing). Fewer goblet cells in smaller airways. Mucus traps macrophages, inhaled particles and bacteria and is moved by the cilia in cephalad direction Dual blood supply: pulmonary artery (venous) and bronchial artery (arterial) Bronchial artery from descending aorta along larger conducting airway carries oxygenated blood to lung tissue

Answer 19

Haemothorax: blood between pleura Pleural effusion: fluid build up between pleura Pneumothorax: Air between pleural layers Pyothorax/empyema: pus/infection within pleura Vanishing tumour: fluid within fissures of lungs During PE: occlusion to branch of pulmonary artery NOT bronchial Hemorrhagic necrosis: alveolar spaces filled with blood; shows opacity/consolidation in CXR Pleuritis: severe pain; changes with breathing Pleuritic chest pain - pain aggravated with breathing

Answer 20

Inspiration - active: Diaphragm descends (innervated by phrenic nerve C4-5 keeps the thorax alive!) ICS move ribs upwards and outwards Volume of thorax increases Increases negative pressure in thorax and therefore alveoli Suction of air through trachea and bronchi into lung parenchyma Gaseous exchange During REST: 75% respiration is abdominal (diaphragm) 25% thoracic (external ICS)

Answer 21

Expiration - passive Elastic recoil Diaphragm returns ICS relax and ribs move down and inwards Pressure becomes more positive Air forced out of thorax and airway During EXERCISE or respiratory distress: Accessory muscles are recruited during inspiration - sternomastoids, scalenes etc. Ventilation increases and expiration becomes active Expiration causes contraction of abdominal wall and internal ICS Also active during cough reflex

Answer 22

Tubercle in the lung/Granuloma in the body, is an organized collection of macrophages and is a special defensive cell arrangement. Granulomas form when the immune system attempts to wall off substances, it perceives as foreign, but is unable to eliminate. Such substances include infectious organisms including bacteria (MTb etc.), fungi, foreign bodies (suture fragments etc.) In TB, macrophages often fuse to form multinucleated giant cells (Langhans giant cell).

Answer 23

``` Microorganisms Tuberculosis Leprosy Schistosomiasis Histoplasmosis Cryptococcosis Cat-scratch disease (Bartonella henselae) Listeria monocytogenes Leishmania spp. Pneumocystis pneumonia Unknown/Auto-immune Rheumatic Fever Sarcoidosis Crohn's disease Rheumatoid arthritis Granulomas associated with vasculitis FB Foreign-body granuloma Aspiration pneumonia (food particles, pill fragments, …) ```

Answer 24

From deep to superficial: Originate from thoracolumbar fascia, anterior iliac crest and external surfaces of ribs and costal cartilages. Insert in forming rectus sheath surrounding the rectus abdominis muscle. Innervated by thoraco-abdominal nerves. Transversus abdominis: fan like array of muscle extending transversely. Innervated by T6-12 anterior rami and first lumbar nerve. Internal oblique: hands to boobs direction, innervated by anterior rami T6-12 spinal nerves and first lumbar nerve External oblique: hands in pockets arrangement. Innervation T7-11 and subcostal nerve. Free border forms inguinal ligament between the ASIS and pubic tubercle Rectus abdominis: arises from pubic symphysis and pubic crest and inserts into the xiphoid process and 5-7th costal cartilages. Innervated by anterior rami T6-12. 80% people have and insignificant muscle called pyramidalis (located anterior to inferior rectus abdominis) origin pubic crest to the linea Alba. Draws down on the linea alba.

Answer 25

Musculophrenic (descends along costal margin supplies diaphragm) and superior epigastric (descends in rectus sheath supplies ab wall) from the internal thoracic artery 10 and 11th posterior ICA and subcostal arteries from the aorta (supply lateral abdominal wall) Inferior epigastric and deep circumflex from the external iliac artery (deep abdominal wall) Superficial circumflex and superficial epigastric from the femoral artery (superficial abdominal wall)

Answer 26

Males: spermatic cord Females: uterine ligament Both: blood and lymphatics, ilio-inguinal nerve, genital branch of the genitofemoral nerve Has a deep and superficial inguinal ring (openings where the cord enters and exits the abdominal fasciae)

Answer 27

``` Oral cavity Pharynx Oesophagus (T10 crosses diaphragm) Stomach Small intestine: duodenum, jejunum and ileum Large intestine/colon: Cecum (with/without appendix), ascending, transverse, descending, sigmoid Rectum Anal canal ```

Answer 28

Right upper: liver, gallbladder (posteriorly) Right lower: large and small colon, cecum and appendix Left upper: spleen, stomach, pancreas (posterior to stomach) flexure of transverse colon and top of descending colon Left lower: large colon and small intestine Pelvic region: sigmoid colon, rectum, uterus (female), anal canal, perineum

Answer 29

Origin from brachiocephalic which splits into common carotid and subclavian (on the right side) and directly from the arch of the aorta on the left side (left subclavian) Becomes the axillary passing underneath clavicle with the superior thoracic, thoraco-acromial, lateral thoracic, subscapular and anterior/ posterior circumflex humeral arteries branching from it Becomes brachial artery around humeral neck level branching the profunda brachii, superior and inferior ulnar collaterals At the cubital fossa splits into the ulnar (medial) and radius (lateral) artery Radial artery has a radial recurrent branch and ulnar has a posterior and anterior recurrent branch Both are connected by common interosseous artery just under cubital fossa level At the wrist the arteries become the deep and superficial palmar arches which then extend to become the common palmar digital artery (fingers and thumb)

Answer 30

All deep venous networks follow the same name structure as the arteries of the hands and arms Superficial: Hands: dorsal digital network collect venous blood in the hand At the wrist posteriorly are the basilic and cephalic (superficial) veins. These travel and move anteriorly throughout the forearm. Anteriorly the median vein of the forearm travels up from the wrist and joins the cephalic at the ante cubital fossa. The median cubital vein connects the basilic to the cephalic at the cubital fossa level These veins are the most common venous puncture sites: median cubital, basilic, cephalic, brachial (deep) In the arm the basilic and cephalic vein travel anteriorly either side of the deep brachial vein and the basilic joins the brachial forming the axillary vein travelling under the clavicle The cephalic also joins the axillary near the coracoid process of the scapula The axillary becomes the subclavian and the subclavian is joined by the internal and external jugular veins to form the brachiocephalic vein leaving the arm

Answer 31

Abdominal aorta splits at L4 (aortic bifurcation) into the right and left common iliac vessels These split into the internal iliac and external iliac vessels Internal iliac (more internal) branches the obturator, superior and inferior gluteal vessels supplying the obturator externus, pectineus, adductors, gracilis and muscles attached to ischia tuberosity. External iliac branches the inferior gastric which travels on the anterior iliac fossa. External iliac becomes the femoral artery at level of inguinal ligament. Femoral artery travels down to the knee from anterior crossing to posterior via the adductor hiatus Branches the profunda femoris (with perforating branches) which pass through the adductor Magnus, supplying the medial, lateral and posterior parts of the anterior thigh. Profunda femoris branches the medial (supply the head and neck of femur and anastomoses with inferior gluteal artery) and lateral (supplies anterior gluteal region and joins genicular peri-articular anastomoses via the descending branch) circumflex branches At the popliteal fossa the femoral artery becomes the popliteal which splits into the anterior and posterior tibial arteries Anterior travels down the anterior tibia becoming the dorsalis pedis at the ankle level Branches the arcuate artery and all terminates in dorsal metatarsal and dorsal digital arteries Posterior tibial travels posteromedially branching the fibular artery. Splits into the medial and lateral plantar arteries on sole of foot, joined by the plantar arch artery. Then branches into plantar metatarsal then plantar digital arteries to terminate

Answer 32

``` Descending thoracic aorta - Boys May Only Pinch Silly Inane Substances: Bronchial Mediastinal Esophageal Pericardial Superior phrenic Intercostal and Subcostal arteries ```

Answer 33

``` Abdominal aorta - Inside Cold Supermarkets Really Get Icy Liquids: Inferior phrenic (T12; PAIRED) Coeliac artery (T12) Superior Mesenteric artery (L1) Renal arteries (L1-2 PAIRED) Gonadal arteries (L2 PAIRED) Inferior Mesenteric artery (L4) Lumbar arteries (L1-4 TWO PAIRS) ```

Answer 34

Acromioclavicular - gliding Joint less movement than others Scapulothoracic Sternoclavicular - physically a saddle joint but functionally a ball and socket joint Glenohumeral - ball and socket

Answer 35

Ball and socket synovial joint Lax capsule to allow movement - very weak capsule hangs dependent underneath joint therefore making it very unstable Most common dislocation in body however only affects 1-2% of population Head of humerus is 3-4x larger than the glenoid fossa therefore it doesn’t sit in the joint entirely also making it unstable Stability of the joint comes from the rotator cuff muscles and ligaments Glenoid labrum helps deepen glenoid cavity by 2.5mm however is prone to damage from dislocations or from age etc. Causing tears or detachment. Also acts as anchoring point for ligaments Subscapular bursa - can also get bursa infraspinatus but not common. Blood supply from suprascapular, subscapular, anterior and posterior circumflex humeral arteries Innervated by axillary, suprascapular, lateral pectoral nerves

Answer 36

Glenoid fossa and humeral head mismatch size Glenoid labrum helps deepen cavity 2.5mm. Acts as chock block and attachment site for ligaments and long head of biceps. 20% of joint compression effect. Glenohumeral, coracoacromial and corcacohueral ligaments help stabilise Intra articular pressure - negative pressure creates suction between bones holding joint together. If pressure is dissipated dislocation very likely Muscles - rotator cuff (supraspinatus for abduction, teres minor, infraspinatus and subscapularis), long head of biceps and deltoid very important

Answer 37

Superior, middle and inferior glenohumeral ligaments extend from the scapula to the head of the humerus Superior - supraglenoid tubercle to lesser tuberosity blends with coracohumeral ligament to close the rotator interval Middle - labrum or bony glenoid neck to medial to lesser tuberosity inferior to subscapularis tendon, often stretched by heavy lifting Inferior - hammock shaped important for arm abduction to cup head. Between the superior and middle protrudes the supscapular bursa Long head of biceps femoris is continuous with the glenoid labrum Coracohumeral ligament goes from the coracoid process to the humerus Transverse ligament runs above the glenohumeral ligaments over the long head of biceps attachment

Answer 38

Primary - rotator cuff muscles (supraspinatus, infraspinatus, subscapular and teres minor), Deltoid and long head of biceps Secondary - teres major, latissimus dorsi, pectoralis major The cuff muscles actively resist deltoid shear forces - the glenohumeral joint compression centres the humeral head making more stable Rotator cuff tendons blend into the capsule - cuff tension actively tightens glenohumeral ligaments Proprioceotion - joint position awareness and repositioning through continuous afferent input and efferent output

Answer 39

Ligamentum flavum - runs between one vertebrate to another in the foramen Interspinous ligament - runs over the superior and inferior articulating processes Intertransverse ligaments - between transverse processes of superior and inferior vertebrae Posterior longitudinal ligament - runs whole length of spine inside foramen anterior to ligamentum flavum Anterior longitudinal ligament - runs whole length of spine on anterior body of vertebrae Supraspinous ligament - runs length of whole spine on spiney processes

Answer 40

Branches off aorta at level of T12, splits into three: left gastric, common hepatic and splenic artery. Left gastric artery branches off to supply the lesser stomach (also gives of oesophageal branch) and anastomoses with the right gastric artery Splenic artery gives off the posterior gastric artery then supplies the spleen and gives off the left gastroepiploic branch supplying greater stomach Common hepatic artery divides into the hepatic artery proper, gastroduodenal (which gives off the right gastroepiploic branch to the greater stomach and the pancreatic-duodenal superior artery) and supra duodenal artery. These supply the stomach, pancreas, first part of duodenum and distal bile duct. the hepatic artery proper splits into right and left branches. the right gives off the cystic branch which supplies the gallbladder and cystic duct.

Answer 41

Branches off the aorta at level of L1 Gives off the pancreatic-duodenal inferior branch which anastomoses with the superior branch from the gastroduodenal artery (origin common hepatic) to supply the pancreas and duodenum Gives off the middle, right and iliocolic arteries which all supply the large intestine as well as several other branches to the small intestine. All these anastomose together the mesentery fascia

Answer 42

Branches off aorta at level L4 Gives rise to left colic artery (supply colon), which in turn gives rise to sigmoid branch supplying the sigmoid colon Later the inferior mesenteric artery splits into the sigmoid branch and superior rectal. The sigmoid anastomoses with the other sigmoid branches to supply the colon while the superior rectal supplies the rectum

Answer 43

The first left and right ICV drain the first ICS directly into the brachiocephalic veins The right and left 2nd and 3rd ICV drain into the superior ICV The left superior ICV joins the left brachiocephalic while the right superior ICV joins the azygos vein. The 4-7th left ICV joint the accessory hemiazygos vein (crosses the vertebrae at T6 to join the azygos The 8-12th left ICV join the hemiazygos vein (arises from ascending lumbar vein), crossing over around T7 to join the azygos All ICV after the 3rd on the right side drain into the azygos vein directly The azygos arises from the IVC, passes through the aortic hiatus (T12) and drains into the SVC at the 2nd ICS level posteriorly.

Answer 44

Begins at capillaries of the GIT, gallbladder, pancreas and spleen. Tributary veins drain these organs directly into the hepatic portal vein branches in the liver, delivering blood to the sinusoids for digestion/processing of carbohydrates, amino acids, lipids, vitamins and iron. These molecules are stored or distributed around the body or degraded and excreted via the kidneys. The hepatic vein then travels from the liver to the IVC, joining just underneath the diaphragm to bring the blood back to the heart and therefore redistribute any molecules put back in via the sinusoids

Answer 45

A serial membrane of the abdominal cavity Peritoneum attached to the organs is termed visceral, while that attached to the body wall is termed parietal. The space in-between (peritoneal cavity) has a small amount of serous fluid to lubricate movements or organs. Organs that have migrated away from the body wall during development are suspended within the peritoneum, and these developments create folds of the peritoneum onto itself within the abdominal cavity, called the greater and lesser omentum (the lesser sits above the stomach, and the greater covering the large and small intestines) The peritoneum suspending the large and small intestines is termed the mesentery, and contains all vessels supplying all of the organ. All innervation comes retroperitoneal from the spinal nerves, and travels to intraperitoneal organs via the mesentery

Answer 46

SAD PUCKER ``` Supradrenal glands Aorta/IVC Duodenum (first 2/3) Pancreas Ureters Colon (ascending and descending) Kidneys (E)Oesophagus Rectum ```

Answer 47

Linea alba Umbilicus Semilunar lines (bilaterally either side linea alba borders rectus sheath) ASIS Pubic symphysis Inguinal grooves (V lines where inguinal ligament would run internally)

Answer 48

Divided into 9 segments by the midclavicular (sagittal) plane, subcostal and transtubercular (transverse) lines Superiorly consists of the right and left hypochondrium regions and the epigastric region (centre division) Middle row consist of the umbilical (centre) region and the right and left lateral regions Inferior row consists of the right and left inguinal regions and the pubic (hypogastrium) region in the centre. The division of these helps to localise pain during diagnosis to help determine which organ is causing said pain.

Answer 49

Used to help diagnose appendicitis 1/3rd away from the ASIS (between the ASIS and the umbilicus) is McBurneys point. Palpating this area in patients with appendicitis can cause significant pain

Answer 50

Referred pain is sent to the area of the skin that the corresponding nerve supplies, instead of the organ itself as this is what the brain is most used to receiving so can feel like the pain is elsewhere when it is in fact the organ sending pain signals. The diaphragm is supplied by C4 and referred pain is often in the anterior shoulder Oesophagus supplied by T4/5 often pain is felt in the centre of the thorax between the nipples T6 extends across just under the nipple line T7 runs straight across T8 supplies the stomach, liver and gall bladder - referred pain for the stomach sits roughly on skin anterior to the stomach itself T10 and 11 also supply the liver and gall bladder, extending across the abdomen along the umbilicus line - referred pain sent to umbilicus area T10 supplies the small intestine - referred pain sent to umbilicus area T11 the large intestine - referred pain sent to just underneath the umbilicus area T10-L1 supplies the kidneys and testes and referred pain is found along the inguinal groove regions T11-L1 supplies the urinary bladder and referred pain is around the pubic symphysis

Answer 51

``` Absorption Secretion Storage Motility Digestion ```

Answer 52

Cephalic: chemoreceptors and mechanoreceptors in the nasal and oral cavity are stimulated by tasting, chewing, swallowing, smelling food or eating, engaging primary neuronal responses. Mainly mediated by Vagal nerve (cranial nerve 10) Gastric phase: begins when food enters the stomach and is linked to stomach distension and contents (amino acids and peptides) engaging neuronal and hormonal responses (local nervous secretory responses, vagal reflexes and gastrin-histamine stimulation) Intestinal phase: left stomach enters the intestines, involves intestinal contents (proteins, fats, H+ ions) engaging primarily hormonal but also paracrine and neuronal responses. (hormones and neural response)

Answer 53

``` PNS: mediated via vagal nerve and acetylcholine increase secretions increase motility decrease sphincter constriction increase blood flow ``` ``` SNS: mediated via thoracolumbar nerves decreased sections decreased motility increase sphincter contractions decreased blood flow ```

Answer 54

Acetylcholine: Released from PNS. Acts on glands, smooth muscle and blood vessels. Increases secretions, motility and blood flow. ATP: released by SNS. Act on blood vessels to decrease blood flow (construction) Calcitonin-gene related peptide (CGRP): released from afferent sensory nerve, act on blood vessels to increase blood flow Enkephalins. released from the enteric nervous system. Act on smooth muscle to constrict sphincters. GRP: released from PNS and ENS. Act on glands to increase gastrin secretions (increases H+ ions) Norepinephrine: released from SNS acts on glands, smooth muscle and blood vessels to decrease motility, secretion and blood flow Neuropeptide Y: released from ENS and SNS. Acts on smooth muscle to decrease motility Substance P: released from Afferents and PNS. Acts on blood vessels and glands to increase blood flow. Vasoactive intestinal peptide: released by glands, acts on smooth muscle, blood vessels to increase motility and blood flow.

Answer 55

Cholecystokinin (CCK): released by I cells throughout the small intestine (tapering off in the ileum). Acts on the exocrine pancreas, gallbladder and stomach. Acts to increase enzyme secretion, increase gallbladder contraction and decreases gastric emptying. Gastrin: released from G cells in the antrum of the stomach, duodenum and tapering off in the jejunum. Acts on the stomach to increase acid secretion. Glucose insulin peptide (GIP) released from K cells in the duodenum and jejunum. Acts on the stomach and endocrine pancreas to inhibit acid secretion and release insulin Motilin: released from M cells in the duodenum and jejunum. Acts on smooth muscle to increase contractions and MMC Secretin: released from S cells throughout the small intestines (tapering off in the ileum). Acts on the pancreas and stomach. Increases bicarbonate and pepsin secretion

Answer 56

Histamine: released from enterochromaffin-like cells and mast cells. Act on the stomach to increase acid secretion Nitric oxide: released from numerous cell types acting on smooth muscle, blood vessels to relax smooth muscle and increase blood flow Prostaglandins: from numerous sources. Acts on gut mucosa to increase mucous and bicarbonate secretion Somatostatin: released from D cells. Acts on the stomach and pancreas to inhibit secretion.

Answer 57

A highly convoluted thin walled tube The duodenum (1st part) is suspended by the lesser omentum The 2nd/descending and 3rd/horizontal parts are retroperitoneal The 4th/ascending part emerges anteriorly in the common mesentery suspended by the smooth muscle at the duo jejunum junction The jejunum is suspended in the common mesentery as is the ileum. The blood vessels travel in this mesentery to supply the tissues

Answer 58

In the duodenum the submucosal glands of Brunner secrete bicarbonate containing mucus to neutralise HCL entering from the stomach The luminal surface (especially the jejunum) consists of circumferential (ring like) folds called plicae circulares composed of mucosal and submucosal tissue Mucosal surface is filled with villi and deep tubular glands (crypts) lined by simple columnar goblet cells for secretion and absorption. They produce a watery medium promoting uptake of minerals and nutrients Enter-endocrine cells secrete hormones such as CCK and secretin to encourage glandular secretion Paneth cells secrete lysosomes into the crypts for digestive enzymes to destroy bacterial cells The vascular lamina propria supports the lacteal (blood vessel) The submucosa supports Large blood and lymph vessels and cell bodies/axons of the parasympathetic neurons Peyers patches are found in the submucosal and lamina propria and are masses of lymphoid nodules mostly located within the ileum Specialised M cells at the epithelium-lymphoid nodule interface play a role in taking antigen to immune reactive lymphocytes, also located in the ileum

Answer 59

C3 - hyoid bone C4 - thyroid cartilage C6 - beginning of trachea and oesophagus T4 - aortic arch and sternal angle of Louis T8 - IVC hiatus T10 - oesophageal hiatus T12 - aortic hiatus L1 - transpyloric plane (fundus gallbladder, neck of pancreas) L4 - iliac crest and aortic bifurcation

Answer 60

``` Constituent: Mouth Larger part of the pharynx Gullet (esophagus) Stomach Small intestine Colon ``` The accessory digestive organs include: ``` Teeth Tongue Salivary glands Liver Gall bladder Pancreas ```

Answer 61

'brain of the GIT' Has around 100 million neurons, extending from oesophagus to anus. Can operate independently of the ANS but still subject to regulation via neuronal control. The Auerbach's plexus/plexus myentericus and the Meissner plexus/plexus submucosus constitute the nervous system of the intestinal wall The Auerbach's plexus controls the motility of the GIT as well as frequency and strength of muscle contractions. Motor neurons of the plexi supply the longitudinal and circular muscle layers of the muscularis The messier plexus innervates the secreting cells of the mucosa epithelium via motor neurons so controls GI secretion

Answer 62

Swallowing occurs in 3 stages: Voluntary phase Pharyngeal phase Esophageal phase Voluntary phase begins with the bolus of food being moved up and down by the tongue and forced against the palate in the posterior oral cavity and the oropharynx The involuntary phase begins with the entry of the bolus into the oropharynx. Receptors are stimulated and transmit to the medulla and lower pons. Inducing the upward movement of the soft palate and uvula and to close the nasopharynx preventing more food being swallowed. The epiglottis closes the laryngeal opening also preventing it enter the respiratory system. Once the oesophageal sphincter is relaxed the food bolus enters the oesophagus The oesophageal phase begins when the bolus enters the oesophagus. Peristalsis propels the bolus pushing it to the stomach. When the lower oesophageal sphincter relaxes it can then go into the stomach.

Answer 63

Once food reaches the stomach, mixing waves occur every 15-a 25 seconds. Food is macerated (soaked and softened) and converted to chyme by the gastric gland secretions. Mixing waves increase in strength when chyme nears the pyloris. This is followed by gastric emptying and the chyme enters the duodenum as each mixing wave periodically pushes small bits of chyme out via the pyloric sphincter. The remaining amount is pushed back into the corpus of the stomach, constantly back and forth to ensure good mixing. The food will have emptied from the stomach within a few hours from intake. Carbs spend the least time there while food with high protein content remains longer, fatty food remains longest. Only a small amount of food is absorbed (water and certain medications like aspirin, and alcohol) here since the epithelial cells are impermeable to most substances.

Answer 64

Salivary amylase is inactivated once chyme mixes with gastric acid. Tongue lipase is activated which degrades triglycerides into fatty acids and diglycerides. Microbes taken in with food are killed by the high acidity, proteins are also partially denatured by the Hydrochloric acid (secreted by parietal cells). But the Hcl stimulates secretion of hormones promoting flow of bile and pancreatic juice. Pepsin is active in acidic environments and digests proteins. To prevent digestion of proteins in the stomach wall it is secreted in its inactive form pepsinogen and is activated by Hcl. Parietal cells are also needed for Vit B12 absorption Gastric lipase cleaves triglycerides into fatty acids Pancreatic lipase is also a significant digestion enzyme

Answer 65

Every day, the pancreas produces about 1200–1500 mL of pancreatic juice, characterized by clear, colorless fluid. It mainly consists of water, a little salt, sodium carbonate, and a few enzymes. Sodium carbonate in the pancreatic juice increases the alkaline pH value slightly, which activates the digestive enzymes in the small intestine: Consists of the head, neck, body and tail Mostly formed of acinar sac-like exocrine glands that secrete enzymes and sodium bicarbonate It is secreted into tributaries of the pancreatic duct and then the duodenum via the ampulla sphincter Trypsin cleaves proteins into amino acids, lipase digests fats and amylase helps digest carbohydrates Pancreatic secretion is regulated by CCK and secretin primarily, as well as ACh from the vagal nerves

Answer 66

Consists of ducts transporting bile from the liver cells to the gallbladder and second part of the duodenum Bile if formed within the liver hepatocytes (consists largely of water, bile and pigments from spleen and RBC breakdown) It is then discharged into the surrounding bile canaliculi, which then merge into bile ductules that converge with intrahepatic branches of the portal vein and hepatic artery Bile is brought out of the liver by the right and left bile ducts, merge at the porta hepatis, to form the common hepatic duct The duct is joined by the cystic duct (from the gallbladder) to form the bile duct Joins with the pancreatic duct forming the ampulla of Vater in the wall of the second part of the duodenum

Answer 67

Chyme enters the duodenum. This stimulates the intestinal mucosa to produces secretin and cholecystokinin pancreozymin (CCK). CCK triggers the release of pancreatic enzymes into the bloodstream, ensuring rhythmic contraction of the gall bladder and stimulation of bile secretion to be released via the bile duct The papilla of Vater is in the middle of the duodenum and is the point where the junction of bile and pancreatic ducts enter Further digestive enzymes are released from both to process the acidic chyme. At the same time the chyme is also neutralised via alkaline secretions of the duodenum.

Answer 68

90% of food absorption occurs via diffusion, osmosis and active transport. 10% occurs in the stomach and colon All monosaccharides are transported via facilitated diffusion or active transport. Faeces only contains indigestible cellulose and fibres. Fructose is transported via facilitated diffusion while glucose and galactose via secondary active transport (Na+ gradient needed) Most proteins use active transport mainly in the duodenum and jejunum Some amino acids need Na+ dependent transport similar to glucose Di and tripe-tides need at least a symporter (Na+) to enter cells for hydrolysis to single amino acids Dietary fats use simple diffusion once digested enough. Bile salts facilitate formation of micelles which can transport lipids and lipid soluble vitamins (A, D, E and K) and cholesterol Bile salts are reabsorbed within the ileum and returned to the liver via the hepatic portal system

Answer 69

A dermatome is an area of skin supplied by a single spinal nerve. ``` Dermatomes of the head are supplied by branches V1, V2 and V3 of the trigeminal nerve: Trigeminal nerve (CN V) ``` V1: ophthalmic branch – the lateral aspect of the forehead V2: maxillary branch – the cheek V3: mandibular branch – the lower jaw (avoid the angle of the mandible as it is supplied by C2/C3) Other C2: 1-2 cm lateral to the occipital protuberance C3: the supraclavicular fossa in the midclavicular line.

Answer 70

C4: over the acromioclavicular joint. C5: the lateral aspect of the lower edge of the deltoid muscle (known as the “regimental badge”). C6: the palmar side of the thumb. C7: the palmar side of the middle finger. C8: the palmar side of the little finger. T1: the medial aspect antecubital fossa, proximal to the medial epicondyle of the humerus.

Answer 71

T2: the apex of the axilla. T3: the intersection of the midclavicular line and third intercostal space. T4: the intersection of the midclavicular line and the fourth intercostal space at the level of the nipples. T5: the intersection of the midclavicular line and the fifth intercostal space, horizontally located midway between the level of the nipples and the level of the xiphoid process. T6: the intersection of the midclavicular line and the horizontal level of the xiphoid process. T7: the intersection of the midclavicular line and the horizontal level at one quarter the distance between the level of the xiphoid process and the level of the umbilicus. T8: the intersection of the midclavicular line and the horizontal level at one half the distance between the level of the xiphoid process and the level of the umbilicus. T9: the intersection of the midclavicular line and the horizontal level at three-quarters of the distance between the level of the xiphoid process and the level of the umbilicus. T10: the intersection of the midclavicular line, at the horizontal level of the umbilicus. T11: the intersection of the midclavicular line, at the horizontal level midway between the level of the umbilicus and the inguinal ligament. T12: the intersection of the midclavicular line and the midpoint of the inguinal ligament.

Answer 72

L1: the inguinal region and the very top of the medial thigh. L2: the middle and lateral aspect of the anterior thigh. L3: the medial epicondyle of the femur. L4: the medial malleolus. L5: the dorsum of the foot at the third metatarsophalangeal joint. S1: the lateral aspect of the calcaneus. S2: at the midpoint of the popliteal fossa. S3: at the horizontal gluteal crease (the horizontal crease formed by the inferior aspect of the buttocks and the posterior upper thigh). S4/5: the perianal area.

Answer 73

A group of muscles innervated by a single spinal nerve. ``` C4: shoulder shrugs C5: shoulder abduction and external rotation; elbow flexion C6: wrist extension C7: elbow extension and wrist flexion C8: thumb extension and finger flexion T1: finger abduction L2: hip flexion L3: knee extension L4: ankle dorsiflexion L5: big toe extension S1: ankle plantarflexion S4: bladder and rectum motor supply ```

Answer 74

Cervical plexus (C1 – C4): innervates the diaphragm, shoulders and neck. Brachial plexus (C5 – T1): innervates the upper limbs. Lumbosacral plexus (L2 – S1): innervates the lower extremities.

Answer 75

Completion of resorption Formation of certain vitamins Formation of feces Excretion of stools from the body

Answer 76

Chyme from the ileum is regulated by the ileocecal sphincter. Peristalsis is increased post meal by the stomach-ileum reflex, transporting the chyme into the cecum. This movement across the sphincter stimulates the colon to produce austral contractions and peristalsis. No enzymes are secreted, all digestion here is carried out by bacteria. Several vitamins (B and K included) are absorbed here. The glands of the mucosal wall only secrete mucus to lubricate the bolus. Chyme remains in the colon for approx. 3-10 hours before it becomes solid or semi-solid due to water absorption by the colon. The resulting stool is made of excess water, inorganic salts, GI epithelial cells, bacteria, products of bacterial metabolism or indigestible food parts.

Answer 77

Produces 1.5–2 liters of fluid that contains enzymes that help to break down carbohydrates and fats, proteolytic proenzymes (preliminary stages of enzymes), and bicarbonate. Aids in meal digestion through the merocrine secretions that it produces. Malnutrition and malabsorption result without the exocrine pancreas. Bicarbonate creates an alkaline pH (7.8-8) and also helps neutralise the acidity in the duodenum via secretion through the ductus pancreaticus. Enzymes produced: ``` Trypsinogen and chymotrypsinogen Procarboxypeptidase Proelastase Lipase Cholesterinesterase enzyme α-amylase Ribonuclease and deoxyribonuclease ```

Answer 78

The duodenal cuticular layer and the Brunner’s glands secrete the enzyme enterokinase that transforms trypsinogen into trypsin. Trypsin transforms all of the other pancreatic proenzymes into their active forms

Answer 79

PNS ganglion are located in the peripheries, neurotransmitters tend to only be ACh to muscarinic receptors SNS located adjacent to the spine (short pre-ganglionic neuronal and long post-ganglionic) neurotransmitters tend to be noradrenaline to alpha or beta receptors but can be ACh to muscarinic receptors

Answer 80

``` 31 pairs 8 cervical - all arise above the corresponding vertebrae aside from C8 which comes from below. all other nerves arise from below after this. 12 thoracic 5 lumbar 5 sacral 1 Coccygeal ```

Answer 81

Brain: white matter in the middle grey In the peripheries Spinal chord: white matter in peripheries and grey in the centre Ratio of the grey to white is low in the cervical section and increases inferiorly (gets bigger going down the spine into thoracic, lumbar, sacral etc) Ratio is high in sacral bodies (lots more axon tracks joining the spinal cord so lots more myelinated axons) Grey matter: is divided into 'horns' which have a functional division: - dorsal horn receives sensory input - ventral horn houses alpha and gamma motor neurons - There is an intermediate horn in T1 - L2/3 which houses visceral motor output (sympathetics relay here)

Answer 82

Superiorly should be very smooth while inferiorly is not due to ligament articulations and subclavian groove (attachment for subclavius). Then to orientate left or right: find smooth smaller end that articulates with the sternum and other larger end is acromial end

Answer 83

Sternoclavicular: elevation and depression and protraction (forward) and retraction (back) Glenohumoral: extension, flexion, adduction and abduction, internal (medial) and external (lateral) Elbow: flexion, extension, supination, pronation, Wrist: flexion, extension Fingers: flexion, extension, finger adduction and abduction

Answer 84

Axial: supportive structure of the body. Includes the skull, vertebrae, sternum, ribs and hyoid bone Appendicular: Makes possible a considerable degree of movement in the body. Includes the pictorial and pelvic girdles, upper and lower limbs

Answer 85

Long bones: Clearly long and have a medullary cavity, hollow diaphysis of compact bone and at least 2 epiphyses eg femur or phalanx Short: are cuboid shaped, predominantly cancellous bone with thin cortex of compact bone with no cavity. eg carpal or tarsal bones Flat: generally more flat than round eg cranial or ribs Irregular: Have more than two shapes within them such as scapulae or vertebrae Sesamoid: developed in tendons, often mixed with fibrous tissue and have a cartilaginous articular surface facing an articular surface of an adjacent bone. May be part of a synovial joint, generally pea sized (pisiform) the largest being the patella. They resist friction and compression, enhance joint movement (fulcrum for joint) and may assist local circulation

Answer 86

Immovable/synarthroses Partly moveable/amphiarthroses Freely moveable/diarthroses FIBROUS joints are connected by fibrous tissue eg sutures of the skull and are immovable. Syndesmoses are partly moveable fibrous joints such as interosseous ligaments between the bones of the forearm and leg Cartilaginous joints (synchondroses): essentially immovable and are seen during growth such as epiphyseal plates Fibrocartilaginous joints are partially moveable eg intervertebral discs Symphyses are also partly moveable fibrocartilaginous joints such as the pubic bones and manubrium and body of the sternum. Synovial joints (diarthroses) are freely moveable. They are capped with articular cartilage and enclosed by fibrous joint capsule lined by synovial membrane with internal synovial fluid lubricating it

Answer 87

Ball and socket: hip and shoulder: allows flexion, extension, adduction, abduction, internal and external rotation and circumduction Hinge: ankle, interphalangeal joints: flexion and extension only one plane of movement Saddle joint: carpometacarpal joint at thumb base: permits all actions but rotation Ellipsoid: radoiocarpal joints: reduced ball and socket joint with reduced rotation able Pivot joint: C1 and C2 vertebrae: allows pivot movement Gliding joints: acromioclavicular, inter carpal, inter tarsal joints: allows sliding small motions in all directions without rotation. Have flat articulating surfaces

Answer 88

The duodenum and jejunum are roughly similar in wall structure, the main differences between these two and ileum is the duodenum and jejunum have fewer peyer's patches (lymphoid nodules) than the ileum, but have many more villi folds within the wall* Ileus has shorter villi, M cells are present and lymphoid aggregates forming follicles (Peyer’s patches) that extend throughout the lamina propria and submucosa

Answer 89

refers to the smooth muscle that surrounds the end portion of the common bile duct and pancreatic duct. This muscle relaxes during a meal to allow bile and pancreatic juice to flow into the intestine.

Answer 90

Serves as a storage chamber for bile discharged from the liver Bile is concentrated here The walls have multiple microvilli on luminal surfaces of the simple columnar epithelial cells that absorb water from the dilute bile When the duodenum releases CCK in response to fat this stimulates the contraction of the gallbladder to discharge its contents into the cystic duct via peristaltic contractions

Answer 91

Muscular tube 23-25cm long connects the pharynx to the stomach Passes through the diaphragm at oesophageal hiatus (T10) Has rich lymphatic system in submucosa Three parts: cervical, thoracic and abdominal Lining of lumen is stratified squamous epithelium Part of the foregut, has three layers but no mucosa: important in cancer spread, bacterial spread after perforation etc. Located in mediastinum Three natural narrow points: upper oesophageal sphincter (anatomical sphincter, cricopharyngeus muscle), middle where aorta/left bronchus pass anteriorly and the lower oesophageal sphincter (gastro-oesophageal junction- physiological sphincter, no special/isolated muscle) Upper one third is striated muscle, somatic sensation, voluntary control Lower two thirds, smooth muscle, visceral sensation, involuntary control Function to transport food using helical peristaltic movements

Answer 92

Two bean shaped organs located in retroperitoneal abdomen between T12-L3 mostly protected by ribs Filter the blood: roughly 150Litres per day (30x total body volume) Regulate blood pH, volume, pressure and osmolality Produce hormones: erythropoietin, renin and 1,25-dihydroxy vitamin D Renal hilum is the entry and exit point for all blood, lymph and nerve vessels and ureters. Biochemical measurements of kidney function: eGFR, BUN and creatinine Structure: Renal fascia outermost layer Adipose capsule Renal capsule Outside rim in renal cortex: divided into outer cortical zone and inner juxtamedullary zone Inner is the medulla: 10-18 renal pyramids make up the medulla. The tips of these pyramids are called renal papilla, these project into minor calyces, which collect forming major calyces and drain into the renal pelvis. Ureter connects to the renal pelvis. Roughly 1 million nephrons per kidney

Answer 93

Roughly 1 million per kidney Divided into the renal corpuscle (begins filtration) made of the glomerulus (capillaries) and the bowman's capsule (renal cells and basement membrane surrounding capillaries) Podocytes line the basement membrane which form the basement membranes filtration slits allowing passage to water, glucose, ionic salts, but preventing passage of large proteins and RBCs The wider diameter of the afferent arteriole compared to the efferent increases the pressure within the glomerulus (hydrostatic pressure) forcing water and solutes out of the capillaries into the bowman's capsule forming the glomerular filtrate (around 170-180 L per day Filtration + secretion + reabsorption = urine Filtrate then passes into the renal tubule Divided into the proximal convoluted tubule, Loop of Henle, distal convoluted tubule and the collection duct which sends the filtrate into the calyces. All around these tubes are blood capillaries to reabsorb necessary solutes from the tubules filtrate Filtrate is fine tuned based on the osmolarity of the blood in the surrounding capillaries Reabsorption of Na, Cl, K ions and water occurs throughout Once passed through this, remaining filtrate drains into the minor calyces, major calyces then the renal pelvis. From here drains into the ureter

Answer 94

Located between the afferent arteriole and DCT Helps to regulate blood pressure and glomerular filtration rate Made up of three cell types: macula densa cells, extraglomerular mesangial cells and juxtaglomerular cells Macula densa cells are located in DCT, detect when Na, Cl levels are low, send signal to JG cells (located in wall of afferent arteriole) Signalling is assisted by the extraglomerular mesangial cells JG cells independently detect low BP and also receive signal from MD cells and will secrete renin to increase Na reabsorption, increase blood volume, increase constriction of blood vessels and increase blood pressure

Answer 95

Transports urine from the kidneys to the bladder to be stored One tube each kidney arise from the renal pelvis and enter the bladder at the ureterovesical junctions Descends retroperitoneally anterior to psoas major, at level of sacroiliac joint crosses over pelvic brim and enters the pelvic cavity, also crossing over bifurcation of common iliac arteries At level of ischial spine will run underneath the ovarian artery or vas deferens Runs laterally in pelvis when reaching the ischial spines runs transversely to pierce the bladder at ureterovesical junction, forming one way back flow valve Has three narrower points where blockages are more likely to sit/get stuck: Ureteropelvic junction Pelvic brim Ureterovesical junction

Answer 96

Sectioned into apex, body, fundus, trigone area and neck and the detrusor muscle Positioned behind the uterus and anterior to rectum in women (forms vesicouterine and rectouterine pouches - pouch of douglas, common place of peritonitis pus accumulation, can be drained transvaginally). Anterior to rectum in males (forms rectovesical pouch) Holds around 750ml, less in women especially when pregnant) Trigone region: sensitive to expansion, once expanded sends signal to brain to urinate (corners are ureterovesical junctions and the internal urethral orifice) Ureterovesical junction is where the ureter joins the bladder and also acts as a valve to prevent backflow of urine as the bladder expands the valve is pushed closed Muscular wall with many folds called rugae (contract when empty but expand when full) Layer of transitional epithelium is stretchy allows for distention while maintaining barrier between urine and the body Also thick muscle layer called detrusor muscle: helps with contraction of the bladder during urination Fibrous adventitia outer layer

Answer 97

Drains the urine from the bladder In men: Divided into preprostatic (just before prostate), prostatic, membranous (intermediate passes through pelvic diaphragm) and spongy (through penis) sections. Males also use urethra during ejaculation, semen entering via the ejaculatory ducts just above the prostate. In females: runs through the perennial floor of pelvis and exits between two labia minora. Above vaginal opening and below the clitoris in an area called the vulva vestibule Around the internal orifice the detrusor muscle thickens to form the internal sphincter (involuntary control by ANS). keeps bladder closed when not full External sphincter at level of urogenital diaphragm under voluntary control. Contracts skeletal muscle around the sphincter can stop urination, kegel exercises use this muscle.

Answer 98

When the bladder is around half full (300-400ml) stretch increase is detected and signals sent to the micturition (urine) center at S2+3 of spinal cord Sets of micturition reflex arc: contraction of bladder and relaxation of sphincter Pontine storage center helps control urination when urination cannot happen immediately: stops micturition reflex activation. Once able, will then activate and allow micturition center and reflex to commence Storage of urine: Low level bladder afferent firing, secondary to bladder distention. Increases sympathetic outflow to the bladder outlet and external urethral sphincter (guarding reflex). Sympathetic signalling also acts to inhibit detrusor muscle contractions Micturition: At bladder capacity, high level bladder afferent activity activates the pontine-micturition center. In turn this inhibits the guarding reflex. Activated poutine-micturition center under appropriate conditions will lead to parasympathetic outflow to bladder and internal sphincter smooth muscle. Urinary sphincter relaxation soon followed by large coordinated detrusor muscle contraction, leading to expulsion of urine from bladder

Answer 99

``` made up of 3 columns of tissues corpus spongiosum: - Contains urethra - Extends to form glans penis - Is main organ of sexual pleasure in males ``` two corpus cavernous - columns of erectile tissue, fill with blood during erection

Answer 100

Seminal vesicles: secrete alkaline fluids with fructose, enzymes and prostaglandins. This neutralises acidity of the female reproductive tract. Prostaglandins provide motility and viability of sperm Prostate gland: produces around 40% semen. Secretes citrate (energy source for sperm motility). Secretes enzymes (to break down semen clot once in females reproductive tract) Bulbourethral glands: secrete fluid containing mucus

Answer 101

Male gamete produced in the testes, enters pelvic via ductus deferens through inguinal canal Three important cell types: sertoli (spermatogenesis), leydig (testosterone production and secretion), germ cells (making spermatogenesis) As the testes migrate in development to scrotum they’re enclosed in peritoneal sac called tunica vaginalis Parietal layer: lines inside internal spermatic fascia Visceral layer: closely applied to testes, epididymis and ductus deferens Thin film of fluid between layers allows movement Actual testicle covered by tough membrane called tunica albuginea Sperm generated in convoluted seminiferous tubules within testes These converge and form rete testis that passes to epididymis via efferent ductules Epididymis passess posterior to tesis and thins to a tail that is continuous with the ductus deferens. The epididymis is where the sperm are stored, matured and then conveyed to the ductus deferens The ductus deferens run in the spermatic cord to enter the pelvis via the inguinal canal

Answer 102

Ductus deferens start at epididymis, cross iliac vessels and run over ureters. As they approach the seminal vesicle they dilate and are called ampulla Run through ductus deferens, enter inguinal canal via superficial ring then the deep ring to enter the pelvis, then run alongside the bladder The sweep over the bladder around the circumference, (two ductus deferens, one per testis) As they run alongside the posterior bladder they become dilated and are known as the ampulla of the ductus deferens. They run past the seminal gland here. Seminal fluid is produced in the seminal gland (on the inferior posterior surface of the bladder). Seminal fluid assists sperm to survive in the vaginal canal once ejaculed Seminal vesicle secretes thick alkaline fluid into prostatic urethra. Unites with ductus deferens = ejaculatory duct Ejaculatory duct: slender tube that passes through substance of prostate and opens into seminal colliculus (area of prostate)

Answer 103

GnRH from the hypothalamus stimulates LH and FSH to be released from gonadotropes in the anterior pituitary gland, which target the gonads Gonads produce testosterone and oestradiol which negatively feedback at level of pituitary and hypothalamus Actions of LH: regulates leydig cell (makes testosterone) FSH: regulates sertoli cells (spermatogenesis, synthesis of growth factors, regulatory peptides)

Answer 104

Primary male hormone. Androgen hormone Produced in leydig cells from cholesterol precursors, stimulated by luteinizing hormone Bound by sex-binding globulin or serum albumin and corticosteroid binding globulin 2% testosterone is ‘free’ and this is the active form targeting the seminal vesicles, prostate gland, muscle and bone. Can be converted to other hormones like dihydrotestosterone DHT (more potent form) Testosterone feeds back on HPG axis to regulate levels Testosterone levels tend to decline slightly with age; leads to decline of libido, testis size, bone density, muscle and erythropoiesis and increases fat Eventually excreted by kidneys

Answer 105

Bone Increases growth of bones and connective tissue and closure of bone plates in later puberty Muscle Increases growth of muscle and connective tissue Reproductive organs Increases growth and development of testes, prostate, seminal vesicles, penis Increases growth of facial hair, axillary and pubic hair Increases growth of larynx Increases spermatogenesis Skin Increases sebaceous gland size and secretions

Answer 106

Primary sexual characteristics: Reproduction Enlargement of penis and testes Increased libido ``` Secondary sexual characteristics: Masculinity Male hair pattern Soft and coarse hair Larynx and vocal fold changing to deepen voice Growth spurt Muscles Erythropoiesis (men have more RBC) ```

Answer 107

Production of mature male gametes 200-300 million sperm made per day in testes Undergo maturation in the epididymis Seminiferous tubules have central lumen and outer walls. This is main site of sperm production Primary germ cells in wall of seminiferous tubules Two phases: spermatocytogenesis (germ cells mitosis and meiosis) and spermiogenesis (maturation and differentiation) Spermatocytogenesis: Primary spermatogonia type A divide into type B (function to reproduce and maintain number of type A cells) and primary spermatocyte (diploid cells made by mitosis) Primary spermatocyte undergoes meiosis 1 to give two secondary spermatocyte cells (haploid) These then give rise to two pairs (four) spermatids, by undergoing meiosis 2 During all these division, sertoli cells provide nutritional support Spermiogenesis: 4 phases: Golgi phase: golgi body enzymes form the acrosome Acrosomal phase: acrosome condenses around nucleus Tail phase: centriole elongates to form the tail Maturation phase: loss of excess cytoplasm and mature but non-motile sperm is formed Spermiation: Release of mature sperm from seminiferous tube wall into the lumen Will spend few days within the epididymis and during this time will gain motility These sperms are now capable of fertilisation

Answer 108

``` Varicocele drains into spermatic vein within inguinal canal on each side Left internal spermatic vein then drains into the left renal vein at a right angle and increased pressure in vertical column of blood can lead to dilation of pampiniform plexus Left inguinal spermatic vein is also 8-10cm longer resulting in increased hydrostatic pressure The right internal spermatic vein drains at an oblique angle into the IVC giving more protection/decreased pressure Bilateral varicoceles (10% cases) may occur from cross circulation from left to right pampiniform plexus ```

Answer 109

PNS: Somatic: spinal nerves (sensory, motor, mixed) and cranial nerve (sensory, motor, mixed) Autonomic: sympathetic and parasympathetic CNS: Brain Spinal cord

Answer 110

Comprised of 8 cranial bones (forms vault for brain) and 14 facial bones (giving origin to facial muscles) Cranial - Only Parents From Texas Ever Spit (Occipital, Parietal, Frontal, Temporal, Ethmoid, Sphenoid) Facial - Never Vomit Later Past Midnight, Might Invite Zebras (Nasal, Vomer, Lacrimal, Palatine, Maxilla, Mandible, Inferior nasal concha, Zygomatic)

Answer 111

Comprised of 8 cranial bones (forms vault for brain) and 14 facial bones (giving origin to facial muscles) Cranial - Only Parents From Texas Ever Spit (Occipital, Parietal, Frontal, Temporal, Ethmoid, Sphenoid) Facial - Never Vomit Later Past Midnight, Might Invite Zebras (Nasal, Vomer, Lacrimal, Palatine, Maxilla, Mandible, Inferior nasal concha, Zygomatic) Aside from the temporomandibular joint (synovial joint) all other bones are connected by fibrous sutures which ossify overtime into synostoses The orbit is made of seven bone (frontal, ethmoid, sphenoid, lacrimal, zygomatic, palatine and maxilla) The orbit has two fissures and one canal and is home to the eye and related muscles, nerves and vessels The lacrimal bone is the most delicate of the skull The skull is thickened into pillars (buttresses) in some areas to maintain strong resistance to force by transmitting it away from vulnerable orbits, nasal cavity and brain helping resist fracture. Three of the most obvious buttresses are the superior, lateral and inferior orbital. There are also some around the mouth (masticatory), chin (mental tubercle) and back of the skull (occipital) There are many foramina for nerves and vessels to travel through to supply the head. There is a three paired foramina in the vertical plane above and below the orbit and in the mandible which are exit points for the supraorbital, infraorbital and mental nerves supplying the skin of the face The foramen magnum is in the centre of the occipital bone and transmits the lower brain stem/spinal cord, the large occipital condyles articulate with the facets of the first vertebra (atlas) The pituitary gland sits in a saddle shaped sella turcica above the sphenoid sinus. On either side if the cavernous sinus (filled with venous blood) these can become disrupted forming cavernous sinus thrombosis resulting in raccoon black eyes, swelling and risk of occult (hidden) venous haemorrhage.

Answer 112

SKIN CONNECTIVE TISSUE APONEUROSIS LOOSE CONNECTIVE TISSUE PERIOSTEUM Then bone, the meninges (dura, arachnoid, subarachnoid space with CSF then pia mater adhered to brain tissue)

Answer 113

20 days after fertilisation: embryo in amniotic cavity attached on ventral side to yolk sac Over the next 4 days the three basic germ layers develop: ectoderm (dorsal - epidermis/nails, central and peripheral nervous system), endoderm (ventral - gives rise to GIT, liver etc) and mesoderm (between layers - gives rise to muscle, heart, blood, dermis, connective tissues and more) Development of the neural tube occurs around 21-22 days Develops from dorsal surface (ectoderm) A longitudinal groove forms on thickened layer of germ layer (neural plate) Along the centre of plate the groove deepens, forming neural folds on either side Neural crest cells split off from ectodermal layer Deepening of neural groove proceeds toward head and tail ends of embryo and by day 22 the dorsal part of folds fuse in central part of groove forming the neural tube During this process the neural tube separates from the ectoderm layer By 24 days the neural tube has progressed to extreme ends of the embryo, much of the neural tube will form the spinal cord and the head of the tube will be the brain By the end of three weeks of embryonic development; three regions of brain are apparent: forebrain, midbrain and hindbrain At 8 weeks the forebrain expands forming the massive telencephalon (future cerebral hemispheres) and the diencephalon (future top of brain stem). The midbrain becomes the mesencephalon (future upper brain stem) and the hindbrain differentiates into the upper metencephalon (future middle brain stem) with large dorsal outpocketing (future cerebellum) and the lower myelencephalon (future lowest part of brain stem) Brian stem narrows to become spinal cord at level of foramen magnum of skull

Answer 114

``` Cerebrum Diencephalon Cerebellum Brainstem (midbrain, pons and medulla) Cortex ```

Answer 115

Formed of paired hemispheres consisting of four major layers: outer cerebral cortex (grey matter), subcortical white matter consisting of association tracts (distributing electrochemical impulses from one cortical area to another) projection tracts (basal ganglia/nuclei include afferent sensory pathways to cortex from spinal cord/brain stem and descending efferent motor pathways from cortex to brain stem/spinal cord), discrete masses of grey matter at base of cerebellum (and paired lateral ventricles of cerebral hemispheres). The cerebral hemisphere appear structurally mirror images, however they differ in function eg Broca’s speech area tends to develop of the left side only (left side tends to be more verbally influenced, right side tends to have more influence over visual, spatial and musical expression) Cerebral cortex is highest functioning area of brain, divided into four ‘lobes’ by sulci or fissures Parts of three of the four lobes contribute to the limbic system, all areas are to some extent involved in storage (memory) PARTS: frontal parietal occipital temporal

Answer 116

Frontal lobe involved in reasoning and abstract thinking (intellectual functions), emotion state, olfaction and memory, production of speech (from Broca’s speech area) and voluntary movement (from precentral gyrus)

Answer 117

Parietal lobes postcentral gyrus concerned with body sensory awareness, taste, language processing, abstract reasoning, body imaging

Answer 118

Temporal lobe involved with language interpretation (Contains Wernicke's area, very important for development of language, speech comprehension) and hearing (auditory area) and has major memory processing area (hippocampus for short term memory) and it’s limbic portions contribute a lot to expressions of emotions and related feelings (amygdala).

Answer 119

Occipital lobe receives, interprets and discriminates visual stimuli from the optic tract and associates these with other cortical areas (eg memory)

Answer 120

The cerebellum consists of two hemispheres with a cerebellar cortex, central masses of motor related (deep cerebellar) nuclei and 3D tree shaped arrangement of white matter (ARBOR VITAE - tree of life). Cerebellum is concerned with equilibrium and position sense, fine movement, control of muscle tone and overall coordination of muscular activity in response to proprioceptive input and descending traffic from higher centres

Answer 121

Smaller of the early forebrains two derivatives sits between the two cerebral hemispheres Consists mostly of paired masses of nuclei and related tracts of white matter arranged around a thin purse like third ventricle Thalamus (pineal gland hanging off posterior thalamus), subthalamus and hypothalamus sit either side of the third ventricle The thalamus consists of several cell bodies and processes that in part process ALL incoming impulses from SENSORY pathways (EXCEPT OLFACTORY) Has broad connections with the motor, general sensory, visual, auditory and association cortices Thalamic activity integrates sensory experiences resulting in motor responses, integrates specific sensory input with emotional motor responses (eg baby crying in response to hunger) and regulates and maintains conscious state (awareness) and is subject to facilitating/inhibitory influences from the cortex The three subthalamic nuclei are concerned with motor activity and have connections with the basal ganglia The hypothalamus maintains neural connections with the frontal and temporal cortices, thalamus and brainstem The anterior hypothalamus regulates BP, temperature and the general ANS and is generally involved in body homeostasis. it synthesises hormones and releases them into the median eminence capillaries of the anterior pituitary; influencing hormonal secretion from here Posterior hypothalamic secretory neurons release ADH and oxytocin into the posterior pituitary gland circulation The pineal gland consists mostly of pineal body and related nuclei and tracts that have connections with the thalamus, hypothalamus and basal nuclei and medial temporal cortex. It is the ONLY UNPAIRED structure in the brain Produced melatonin involved in diurnal cycles and rhythms, may influence the onset of puberty through inhibition of testicular/ovarian function.

Answer 122

Midbrain: cerebral aqueduct, superior, inferior colliculus, cerebral peduncle and superior cerebellar peduncle (peduncle meaning stalk) Pons Medulla oblongata Carries out specific functions associated with cranial nerve nuclei, runs along ascending and descending tracts to higher centres and spinal cord There is a core of short axon neurons integrated into chains called the reticular formation. This diffuse network is called the bureaucracy of the brain and is associated with coming to consciousness, alertness and going to sleep. May be involved in many visceral and somatic reflexes such as respiratory and cardiac involuntary control The brainstem refine messages from basal ganglia and motor cortex and also integrate and modulate muscle tone and posture related impulses (this is the FINAL COMMON NEURONAL PATHWAY to skeletal muscles of the body) and assists in executing precise movements in sequence and at desired moments The superior colliculi make visual reflexes possible and the inferior colliculi make auditory reflexes The pons (meaning bridge) is white matter, travels over the fourth ventricle transmitting afferent fibres. Cranial nerve nuclei V, VI, VII and VIII are located in the pons. Medulla oblongata controls the centres of respiration, heart rate and vasomotor function. Nuclei of nerves VIII, IX, X, XI and XII exist here. The pons and medulla are home to the fourth ventricle

Answer 123

Latin: limbus; border Provides expression of emotional states Principal areas are the medial, anterior, anterior-inferior surfaces of the frontal and temporal lobes and a small portion of the parietal lobe and appear as an incomplete border (hence the name) around the medial aspect of each hemisphere These areas include: orbital and medial prefrontal cortex, cingulate gyrus of medial frontal cortex, parahippocampal gyrus of medial temporal cortex and the amygdala (actually a complex of nuclei)

Answer 124

Bridge connecting the left and right cerebral hemispheres Found beneath to cerebral cortex Is purely white matter only (largest collection of white matter in the brain)

Answer 125

Carotid arteries: branches the anterior and middle cerebral and posterior communicating Vertrbro-basilar arteries: vertebral arteries give off the anterior spinal artery before joining, forming the basilar artery which gives off the cerebellar (3 pairs) and posterior cerebral arteries Circle of willis: formed anteriorly from the anterior cerebral joined by the anterior communicating branch, the lateral aspects formed from the internal carotids and posterior communicating branch (the single direct communication between the carotid and vertebral systems) and posteriorly the posterior cerebral branches arising from the basilar Arteries to the head and neck are principally the subclavian and common carotid arteries arising from the brachiocephalic trunk on the right side and from the aorta on the left Many vessels supplying the neck are from the thyrocervical and costocervical trunks The thyroid is supplied by the inferior thyroid artery from the thyrocervical trunk

Answer 126

The common carotids split into the internal and external at the level of C4. External carotid branches first to the superior thyroid artery (supplies thyroid and critical larynx). It also branches to supply the tongue (lingual artery), facial muscles (facial) and occipital region (occipital arteries). It finishes by splitting into the maxillary (including the middle meningeal artery, supplying the dura mater in groove of temporal bone POTENTIAL RUPTURE SITE FROM TRAUMA CAUSING EPIDURAL HEMATOMA) which supplies the teeth, lower jaw, pterygoid region, nasal cavity, nose, hard and soft palate and the temporomandibular joint and superficial temporal arteries

Answer 127

I Very Thoroughly Check Internal thoracic Vertebral Thyrocervical trunk: branches inferior thyroid, suprascapular and transverse cervical A. Costocervical trunk: branches deep cervical and highest ICA

Answer 128

Internal carotid: branches ophthalmic artery External carotid External carotid branches: Some Ladies Feel Men Often Pose Stupidly Superior thyroid Lingual Facial Occipital Maxillary: including the middle meningeal artery (weak point for injury causing epidural hematoma due to supplying dura mater in temporal bone groove). Branches to inferior and superior alveolar as well as middle meningeal. Posterior auricular Superficial temporal: branches the transverse facial.

Answer 129

Two pairs of arteries supply the brain: the internal carotid system and the vertebral artery system Each internal carotid ends by dividing into the anterior and middle cerebral arteries, just before this division they give off the ophthalmic branch to the orbit. The posterior communicating branch is the single direct connection of the vertebral system with the carotid. There is considerable variation seen in the Circle of Willis The middle cerebral arteries give off small short arteries directed at the basal ganglia often called stroke arteries due to often being a source of intracerebral haemorrhage

Answer 130

I Olfactory SVA olfactory receptors/nasal cavity II Optic SSA visual receptors in retina III Oculomotor GSE extrinsic eye muscles (NOT lateral rectus/superior oblique) and GVE to cillary and pupillary sphincter IV Trochlear GSE superior oblique eye muscle V Trigeminal GSE three division V1-3 (maxillary, ophthalmic, mandibular) VI Abducens to lateral rectus eye muscle VII Facial taste receptors, GSA external ear, SVE muscles of facial expression, middle ear, digastric muscles VIII Vestibulocochlear SSA cochlear part sound sensitive to head balance and movement IX Glossopharyngeal GSA external ear and auditory canal, SVA taste receptors 1/3rd tongue, mouth, pharynx, auditory tube, middle ear, GVA pressure and chemical receptors in carotid body and common carotids, SVE to constrictors in pharynx, GVW parasympathetic fibres to parotid gland X Vagus SVA taste receptors base of tongue and epiglottis, GSA middle ear and auditory canal, GVA pharynx, larynx, GVE muscles thoracic and abdo viscera via ganglia XI Accessory spinal root C1-5 through foramen magnum and jugular foramen to trapezius and sternocleidomastoid muscles XII Hypoglossal to extrinsic and intrinsic muscles of tongue

Answer 131

Lower component of the CNS, taking off from the medulla oblongata at the level of the foramen magnum of the skull and ending at the conus medullaris at level of L2 vertebra Has cervical, thoracic, lumbar and spinal nerves Like the brain is ensheathed in three coverings (meninges): Pia, arachnoid and dura mater. Throughout length of the cord is the central column of grey matter arranged in an H forming four horns surrounded by white matter (funiculi) The grey matter is largely neuronal cell bodies, neuroganglia and unmyelinated fibres while the white matter is largely ascending and descending tracts of axons (appearing white due to myelination) The amount of white matter decreases inferiorly down the spinal cord, especially the sacral section The posterior ‘horns’ receive central processes of sensory neurons and direct to adjacent white matter for conduction to other cord levels of higher centres The anterior horns consist of interneurons and lower motor neurons (final common pathway) for motor commands and skeletal muscle Lateral horns only exist in thoracic and upper lumbar areas and include autonomic motor neurons supplying smooth muscle in vessels, viscera and glands The grey matter is where spinal reflexes occur in conjunction with facilitatory and inhibitory influences from higher centres

Answer 132

thin, vascular pia mater closely applied to spinal cord, the translucent cobweb-like arachnoid mater stuck to the dura and separated from the pia by the subarachnoid space (with thin beams of loose connective tissue called trabeculae come off arachnoid mater and attach to the pia mater) and the outer fibrous spinal dura mater is a prolongation of the cranial dura mater Pia mater formed triangular sheets projecting away from cord to the dura between pairs of nerve roots called denticulate ligaments. Presumably these stabilise the spinal cord. After the spinal cord ends at L2 level, the pia continues inferiorly as a thin cord like pial filum terminale and attaches to the coccyx, ending with the dural sac at vertebral level S2. this cavity is called the lumbar cistern and contains CSF Dural sac continues inferiorly as the dural filum terminale and attaches to the coccyx External to the dura is the epidural space contains loose connective tissue, adipose tissue and venous systems. Injections of pain relief and steroid medications here is a common form of pain management. The veins here are part of external and internal vertebral venous plexus along entire length of spine and is essential part of collateral circulation

Answer 133

31 pairs arising from anterior (motor) and posterior (sensory) roots of the spinal cord 8 cervical C1-8 and 7 cervical vertebrae. These roots pass through the intervertebral foramina with exception of C1 that departs between the occipital bone and C1 (atlas). All exit SUPERIOR to the corresponding vertebrae aside form C8 which exits INFERIORLY to corresponding vertebrae (all all subsequent spinal nerves exit inferiorly due to this mismatch) Anterior rami of C1-4 form the cervical plexus - largely sensory and end as cutaneous nerves of posterior head, lateral neck and shoulder The phrenic nerve (C3-5) is a significant exception innervating the diaphragm Lower cervical nerves C5-8 form the brachial plexus 12 thoracic nerves form no plexuses . anterior rami becomes the ICN (aside from 12th) passing into the costal groove of ribs innervating ICM. laterally they give off a lateral cutaneous branch dividing into anterior and posterior cutaneous branches. Posterior rami and immediately terminate in medial and lateral cutaneous branches supplying muscles T1 is largest thoracic nerve and gives significant branch to brachial plexus T12 subcostal nerve runs below 12th rib, passes down abdominal wall and terminates as cutaneous nerve 4 of 5 lumbar nerves form the lumbar plexus supplies motor innervation of antieor and medial muscle groups of thigh Thoracic and lumbar T1-L2 nerves carry preganglionic visceral efferent fibres to sympathetic chain of ganglia alongside vertebral column bilaterally 4th and 5th lumbar nerves form the lumbosacral trunk, joining the five sacral spinal nerves (sacral plexus) to collectively become the sciatic nerve (L4,5, S1-3) Sacral plexus contributes to superior and inferior gluteal nerves, lateral femoral cutaneous nerve and direct branches to some lateral rotators of thigh

Answer 134

Specific area of skin (derma) innervated by sensory fibres of a single spinal nerve In each spinal dermatome the general somatic afferent neurons transmit temperature, pain, pressure to the spinal cord Dermatome pain reflects both cutaneous and non-cutaneous (visceral) pain referred to the skin (eg skin innervated by same nerve as viscera may show pain response) C1 has no dermatome as has no sensory root, though may ride with C2 C4 and T1 overlap the chest wall as C5-T1 are committed to upper limbs L3 and S3 overlap the low back as L4-S1 are committed to the leg and foot

Answer 135

Fibrous coverings that envelop the brain and spinal cord The meninges of the spinal cord are inferior extensions of the cranial membranes Dura mater is the outermost layer, has two layers: periosteum lining the internal surface of the cranium and vertebral canal and the inner meningeal layer enclosing the entire brain and forming the dural septa or partitions between the lobes A single falx cerebri is a midline septum formed from the joining of the two layers of the meningeal dura The tentorium cerebelli support the occipital lobes and separate them from the cerebellum below. The free edges form a notch (incisura) accommodating the brain stem The arachnoid mater lies deep to the inner dura and then subarachnoid space containing CSF Then the pia mater is the innermost layer . vascular layer of loose connective tissue supporting the vessels reaching the brain and spinal cord by means of trabeculae between the pia and arachnoid in the subarachnoid spaces. It appears inseparable from the brain and spinal cord. In the walls of the ventricles the vessels in the pia form complex secretory plexus with the ependymal lining cells called the choroid plexuses which secrete CSF

Answer 136

Mainly motor neurons in the frontal lobe, motor strip (frontal motor cortex) Fibres carries messages for voluntary motor movement to lower motor neurons in the brainstem and spinal cord An UMN lesion is a lesion ABOVE the lower motor neuron (LMN) a lesion above the anterior horn cell of the spinal cord or motor nuclei of the cranial nerves

Answer 137

Include both corticobulbar and corticospinal tract These are aggregations of efferent nerve fibres from the UMNs that travel from the cerebral cortex and terminate in the brainstem (corticobulbar) or spinal cord (corticospinal) Corticobulbar tract conducts impulses from the brain to the cranial nerves, and control muscles of the face and neck and involved in facial expression, mastication, swallowing etc Corticospinal tract conducts impulses from the brain to the spinal cord. Involved in VOLUNTARY movement. Majority of fibres cross over in the medulla resulting in muscles being controlled by OPPOSITE sides of the brain Pyramidal tracts are names because they pass through the pyramids of the medulla oblongata

Answer 138

``` Type A alpha (group I) fast fibres (thickest myelination) - sensory receptors from proprioception of skeletal muscle Type A beta (group II) fast fibres - sensory receptors of mechanoreceptors of skin Type A delta (group III) - slow fibres (least myelination) - sensory receptors for pain and temperature Type C (group IV) - no myelination at all. Slowest fibres. Sensory receptors for temperature, pain and itch ```

Answer 139

Supportive cells of neuron communication in the nervous system Not directly involved in information processing but provide support to neurons Translates as ‘glue’ as they were thought to hold everything together Types: 6 types, 4 in the CNS and 2 in the PNS: ``` CNS: Astrocyte Microglial Ependymal cells Oligodendrocytes ``` PNS: Satellite cell Schwann cell

Answer 140

astrocytes Central body with projections (not axons or dendrites) Star shaped (astro - star) Function is to maintain chemical concentrations and is important in the blood brain barrier; assisting forming the BBB using foot processes to wrap around capillaries, blocking many substances from crossing Involved in removing waste and can reactive to tissue damage helping repair satellite cells Similar function to astrocytes but found Found surrounding the sensory and autonomic ganglia Thought to regulate microenvironment surrounding neurons

Answer 141

Schwann cells (PNS): Insulate PNS axons Can only myelinate ONE axon individually Oligodendrocytes: Insulate CNS axons Can encapsulate MULTIPLE neuron axons at a time

Answer 142

Micro (small) Function is to ingest cells and pathogens similar to macrophage Important for immune support ``` Ependymal cell: Similar to epithelial cells Function to filter blood to make CSF Found lining the ventricles of the brain in the coronoid process - where cells are in contact with venous blood to filter from Have many cilia to help waft CSF through ```

Answer 143

Somatic: spinal nerves (sensory, motor, mixed) and cranial nerve (sensory, motor, mixed) Autonomic: sympathetic and parasympathetic Sympathetic division: Thoracolumbar outflow, neurons begin at thoracic and lumbar portions of spinal cord (T1-L2) Parasympathetic division: Craniosacral outflow; neurons begin at cranial nerves (CN3, 7, 9 and 10) and sacral spinal cord (S2-4)

Answer 144

Clear, largely acellular plasma like fluid surrounding the brain Suspends the brain and spinal cord within the dura mater in a no-load gravity free (virtually) condition, preserving structural integrity Functions as cushion, blocks brains movement following head strike etc and supplies nutrients to brain Produced in the brain, flows around the spinal cord before returning to the brain Spaces filled with CSF in the brain: lateral ventricles, interventricular foramen, third ventricle, cerebral aqueduct, fourth ventricle and central canal

Answer 145

Complex surrounding most blood vessels in brain helping maintain homeostasis in brain and circulatory system Highly selective barrier between extracellular space of brain and blood of systemic system Water, O2, small lipid soluble molecules only Prevents pathogens and toxins crossing, wall also contains enzymes which can inactivate pathogens but can also prevent TREATMENT drugs from crossing so drugs must be made to get around this also However some diseases can cross BBB leading to increased disease progression: encephalitis, MS, brain traumas, alzheimer’s, epilepsy, strokes, tumours can all breach the BBB Central components are tight junctions of epithelial cells and pores allowing passage of selected molecules as well as astrocytic end feet processes to wrap around the whole vessel. Pericytes also involved in wall formation Circumventricular organs - areas of the brain lacking a blood brain barrier as their function needs direct access to the blood; eg the posterior pituitary. Mostly located near the middle of the brain

Answer 146

Reflex is an involuntary muscle response to a stimulus Most body movements, including viscera, are reflexive eg HR, respiratory rate, peristaltic contraction etc. This is to allow automatic running of systems while allowing more sophisticated thought Spinal reflexes involve sensory receptors, sensory neurons, interneurons (usually), motor neurons and effectors (muscle) A stretch (monosynaptic or myotatic reflex) is the most simple reflex involving two neurons and one synapse. Eg the knee jerk reflex. Activated by stretching tendon of specific muscle activating the neurotendinous receptors (receptors specifically sensitive to distortion and stretch) Muscle spindles are encapsulated specialised muscle fibres with nerve endings sensitive to muscle stretch. The impulse is generated in these receptors, conducted by sensory neurons to the spinal cord (synapse in anterior horn motor neurons) and the motor neuron conducts the impulse to the end plates of the effector muscle causing contraction of muscle resulting in the ‘knee jerk reflex’ Polysynaptic reflexes have more than two neurons in the circuit. Range from simple withdrawal reflexes to complex reflexes involving several segments of spinal cord and brain. The complexity relates to the number of interneurons in the reflex and number of synaptic contacts between stimulus and response. Eg pain, temperature. Pain receptors respond to sharp increase in heat, sensory neuron transmits to spinal cord, interneuron receives impulse and excite one facilitatory and one inhibitory neuron. The excitatory facilitates firing of motor neuron inducing muscle contraction in fingers and simultaneously the inhibitory neuron depresses firing of second motor neuron C3 and antagonist flexor muscle is stretched without contracting, permitting fingers to be withdrawn from flame

Answer 147

Is secreted by the choroid plexus (in fourth ventricles) and minute vessels near the ventricular wall of the lateral, third and fourth ventricles About 150ml CSF circulates through the ventricles and around subarachnoid spaces every 24 hours The choroid plexus secrets CSF into the 1/2nd ventricles and travels down into the 3rd ventricle via interventricular foramen and 4th ventricle by cerebral aqueduct (choroid plexus are also found in 4th ventricle and secrete CSF) and exits via the lateral and medial apertures Lateral aperture takes CSF to pontine cistern while medial takes CSF to the cerebro-medullary system Follows either the cerebellum to the superior cistern, draining into the interpeduncular cistern OR flows down subdural space in the spinal cord to the lumbar cistern. CSF then flows back up spinal cord joining flow into superior cistern From ventral cisterns CSF flows in subarachnoid space across cortical surfaces, draining into the superior sagittal sinus via arachnoid granulations Flows down posterior surface towards the confluence of the sinuses, joining the venous blood from the straight sinus

Answer 148

Split into axial and appendicular Axial: supportive structure of the body. Includes the skull, vertebrae, sternum, ribs and hyoid bone Appendicular: Makes possible a considerable degree of movement in the body. Includes the pectoral and pelvic girdles, upper and lower limbs Bone function: Body support Organ protection Body movement - levers for movement Calcium, phosphate haemostasis and storage Fat storage Hormone production Blood cell production Long bones are responsible for most movements Short bones provide limited motion Flat/irregular bones are mostly for protection

Answer 149

Type of connective tissue composed of osteocytes and bone matrix (extracellular matrix) Bone matrix: collagen, minerals (calcium) to maintain density Collagen = flexible. Calcium = stiffness Bone remodelling: constant recycling of old bone removal, new bone formation to reshape bones (growth); repair everyday micro damages and repair bone fractures This is done by maintaining calcium and phosphate levels in bone Osteoclasts = dissolve old bone Osteoblasts = form new bone tissue Major regulators: PTH, vitamin D, growth hormone, glucocorticoids, thyroid hormones and oestrogen Most common bone disease: osteoporosis.

Answer 150

A bone is comprised of several different types of tissue Mostly made from bone tissue (osseous tissue) but also contains nervous tissue, connective tissue, cartilage and blood vessels Gross anatomy: outer layer is compact bone, inside is honeycomb like spongy bone. Precise arrangement of this varies depending on each bone Cancellous (spongy) bone consists of many interwoven beams (trabeculae) of bone in epiphysis of long bones, bodies of vertebrae and other bones with cavities. Spaces are filled with yellow or red bone marrow and blood vessels. Cancellous bone forms a dynamic lattice truss which increases resistance to weight, postural change, stress or torsion and muscle tension. Compact bone: forms walls of diaphysis and thinner outer surface of other bones where there is no articular cartilage (e.g. flat bones of skull) Medullary cavity: cavity of diaphysis contains red marrow in young people turning into yellow with maturity. Lined by thin connective tissue with many osteoblasts (endosteum) Red marrow: red gelatinous substance made of red and white blood cells in a variety of developmental forms (hematopoietic tissue) and specialised capillaries (sinusoids) in reticular tissue. In adults red marrow is generally limited to sternum, vertebrae, ribs, hips, clavicles, long bones and cranial bones Yellow marrow: fatty connective tissue that does not produce RBCs Nutrient artery: principal artery and major supplier of oxygen and nutrients to the shaft/body of a bone. Its branches snake through labyrinth canals of haversian systems and other tubular cavities of bones

Answer 151

Epiphysis: end of a long bone, mature epiphysis is largely cancellous bone. Articulating surface lined with hyaline cartilage Epiphyseal line is remnant of growth plate from childhood Diaphysis: shaft of long bone. Marrow filled medullary cavity surrounded by compact bone lined by bone cell forming periosteum and internally by the endosteum. Contains yellow bone marrow which is high in fat. Ends of bone are called epiphysis and lined with cartilage for cushion and stress absorption. Red marrow can be found inside cavities of spongy bone which produces RBCs Periosteum: fibrous, cellular, vascular and highly sensitive support sheath for bone provides source of bone cells throughout life. Periosteum covers bone exterior: exterior is dense irregular connective tissue and inner osteogenic layer containing primitive stem cells. Membrane is attached to nerves and blood vessels and perforating fibres connect layer to bone

Answer 152

Flat bones are thin plates of spongy bone covered by compact bone, no well defined cavity for bone marrow and hyaline cartilage covers portions of surface involved with joints

Answer 153

``` Osteogenic cells (stem cells) in periosteum and endosteum Osteoblasts secrete bone matrix and cause bone growth, also actively mitotic. Once surrounded by ECM they differentiate to osteocytes Osteocytes are mature cells that monitor and communicate to maintain bone homeostasis. Bone lining cells found in periosteum and endosteum and help maintain ECM Osteoclasts have multiple nuclei use enzymes to break down bone (resorption) ``` Organic component: cells (osteoblasts and osteocytes etc); osteoid (organic part of bone matrix) a ground substance + collagen fibres which are secreted by osteoblasts which gives flexibility and tensile strength Inorganic: hydroxyapatites (needle like crystal of calcium phosphate) which gives bone its ‘hardness’ These work together to keep bone strong and not too brittle

Answer 154

Bone made of soft flexible frame (matrix) plastered with hard brittle bone mineral (calcium) Osteoblasts deposit ECM to matrix until they are surrounded when they become less active and are known as osteocytes but continue to maintain environment Osteoclasts secrete acids and enzymes to dissolve bone This is known as bone turnover; this turnover is affected by many environmental and hormonal factors (PTH, vitamin D, oestrogens) e.g. exercise increases osteoblast activity, and immobility increases osteoclast activity which alters the balance and ultimately leads to net growth or loss of bone

Answer 155

Mature healthy bone is known as lamellar bone: strong. There are two types: cortical (dense stiff shell superficial outer layer) and cancellous bone is the spongy bone inside; softer and less dense). Cortical bone: blood vessels and nerves travel through haversian tubes (central canal) surrounded by rings of bone called lamella (these run in alternating patterns to give strength against torsion force). Osteocytes sit in little pockets in between this called lacuna Channels remain between osteocytes known as canaliculi The whole circle of bone is known as an osteon this is surrounded by cement line then packed tightly together to form dense hard bone Cancellous bone: spongy bone with less density, more elastic and higher turnover rate. Good for storage of bone marrow

Answer 156

Occurs by intramembranous/endochondral ossification Endochondral process begins about 5 weeks after fertilisation with formation of cartilage models and embryonic connective tissue Over the next 16-25 years the cartilage is largely replaced by bone The rate and duration of this largely determines persons standing height Endochondral ossification begins with a hyaline cartilage model. As the cartilage structure grows its central part dehydrates. Cartilage cells then begin to degenerate; enlarge, die and calcify. At the same time blood vessels bring osteoblasts/ostoeclasts to the waist (sides) of bone. This forms the periosteum. This becomes the supportive tubular shaft for the cartilage model as the cartilage core degenerates and calcifies At about 8 weeks after fertilisation, periosteum blood vessels penetrate the calcifying cartilage and deposit osteoblasts and osteoclasts in the extremes of the shaft (diaphyses) and secrete new bone while cartilage is reabsorbed. This is how endochondral bone replaces cartilage as bones grow Twp sites of this activity are called primary ossification centres and growth of bone is toward these two centres The cavity of developing bone is filled with red bone marrow After the first few years after birth secondary ossification centres begin at the epiphysis and the cartilage between the epiphyseal and diaphyseal ossification centres becomes the epiphyseal plate which is responsible for bone lengthening which lasts for 12-20 years of age The epiphyseal line may remain into maturity

Answer 157

Can compare bone age with chronological age to determine if child’s growth is delayed or not Because of changes during growth can estimate a rough bone age based on limb XRs

Answer 158

Contains lots of water increases pressure/tension threshold Contains chondrocytes in lacunae in Extracellular matrix Has no blood vessels (Avascular tissue) Three types: hyaline, elastic and fibrocartilage and skeletal cartilage is made of all three. Mostly hyaline (found in nose, ribs, larynx and ends of most bones giving support) Elastic cartilage is more stretchy and found in found in ears and epiglottis Fibrocartilage is highly compressible found in areas that must withstand lots of pressure like between the vertebrae

Answer 159

Uniaxial: one plane; biaxial; 2 planes; multiaxial: all three planes. Angular movement: angle between two bones change Abduction: movement away from the midline Adduction: movement toward midline of body Circumduction: circles Rotation: turning around its own axis (hip and shoulders) can be internal or external Supination and pronation - radial movements around the ulna Dorsiflexion and plantar flexion - movements in foot Protraction and retraction - mandibular movements Inversion: turns sole of foot inwards Eversion: turns sole of foot outwards

Answer 160

Most abundant tissue in human body (40% body weight roughly) Act in antagonistic pairs Muscles - fascicle - muscle fibre All wrapped in epimysium (outer layer around muscle) Perimysium (around muscle fascicles) And endomysium (around each muscle fibre) These are continuous with tendon connecting it to bone Most common injuries are sprain (stretch/tear ligament); strain (stretch/tear of muscle); cramps (tightening of muscle); tendinitis (inflammation of tendons) and most commonly caused by overuse or wear and tear Myofilaments make up the sarcomere:

Answer 161

Flexion: anterior deltoid, Extension: teres major, posterior deltoid, latissimus dorsi Abduction: supraspinatus (first 15 degrees), middle deltoid main abductor, trapezius (elevates scapula) Adduction: teres major, latissimus dorsi Internal/medial rotation: anterior deltoid, teres major, subscapularis, latissimus dorsi External/lateral rotation: posterior deltoid, teres minor, infraspinatus

Answer 162

further divided into SUPERFICIAL and DEEP Superficial: Trapezius - accessory nerve. Upper fibres: elevate scapula and rotate during abduction Middle fibres: retract scapula Inferior fibres: pull scapula inferiorly Latissimus dorsi - thoracodorsal nerve Extends, adducts and medially rotates upper limb Deep: Levator scapulae - dorsal scapular nerve elevates scapula Rhomboids major and minor - dorsal scapular nerve retracts and rotates scapula

Answer 163

Deltoid - axillary nerve anterior fibres flexes and medial rotation middle fibres major arm abductor posterior fibres extend and laterally rotate arm Teres major - lower sub scapular nerve adduct and extend and medially rotate shoulder/arm Four rotator cuff muscles: SITS. function to pull the humeral head into glenoid fossa during shoulder movements. They form a cuff around the head of the humerus enforcing joint security. supraspinatus - suprascapular nerve abducts arm first 15 degrees infraspinatus - suprascapular nerve laterally rotates arm subscapularis - upper and lower sub scapular nerves medially rotates arm teres minor - axillary nerve laterally rotates arm

Answer 164

anterior: BBC ALL innervated by musculocutaneous nerve! biceps brachii - supination and elbow flexion brachialis - flexes elbow coracobrachialis - flexion of shoulder and weak adduction posterior: triceps brachii - radial nerve elbow extension

Answer 165

Ulna articulates with the humerus via its trochlear notch. Has large bony prominence the olecranon which can be palpated from anterior cubital fossa. Articulates with the radius at radial notch; then gets smaller/thinner distally. Radius articulates with the humerus proximally and enlarges distally to form the wrist joint with the carpal bones (lunate). The radius allows supination and pronation via twisting around the ulna, while the ulna remains stationary throughout Both bones are connected by interosseous membrane throughout forearm Proximal radioulnar joint: permits radial head to pivot within radial notch making pronation and supination possible. Radial head pivots around the capitulum of the humerus while ulna remains stationary due to constraint of humeroulnar joint The annular ligament attached to the radial notch either side of radius securing the radius in place. It’s not uncommon for children’s annular ligament to ‘slip off’ partially or fully the head of the radius resulting in radioulnar translocations/subluxations (can be caused bilaterally at once by swinging children around by their arms)

Answer 166

Hinge joint between surfaces if trochlea and capitulum of the humerus, trochlear notch of the ulna and head of the radius Synovial joint enclosed in fibrous capsule reinforced by medial (radial) and lateral (ulna)collateral ligaments Movements limited to flexion and extension (hinge joint) Women seem to have about 10 degrees more ‘carrying angle’ than men (from babies adapted to carry them maybe?)

Answer 167

Seven superficial muscles; four of these share a common tendinous origin at the lateral epicondyle of the humerus (ECRB, EDC, ECU and EDM) Five deep muscles They are ALL innervated by the radial nerve! Clinical relevance: wrist drop of the radial nerve (commonly at axilla or radial groove of humerus) will paralyse ALL posterior forearm muscles making extension impossible but flexion is unaffected. superficial: brachioradialis - flexes elbow extensor carpi radialis Longus and brevis - extends and adducts wrist extensor digitorum communis - extends medial 4 fingers extensor digiti minimi - extends little finger and wrist extension extensor carpi ulnas - extension and adduction of wrist aconeus - extends and stabilises elbow and abducts ulna in pronation deep: supinator - supinates forearm abductor pollicis longus - abducts the thumb extensor pollicis brevis - extends MCP joints of thumb extensor pollicis longus - extends all thumb joints extensor indices proprius - extends index finger

Answer 168

split into superficial, intermediate and deep compartment superficial: flexor carpi ulnaris - ulnar nerve flexion and adduction of wrist palmaris longus - median nerve flexion at wrist flexor carpi radialis - median nerve flexion and abduction of wrist pronator teres - median nerve pronation of forearm intermediate: flexor digitorum superficialis - median nerve flexes MCP and PIP joints deep: flexor digitorum profundus - medial half ulnar nerve; lateral half median nerve flexes DIP and MCP joints and wrist flexor pollicis longus - median nerve flexes IP and MCP thumb joints pronator Quadratus - median nerve pronates forearm

Answer 169

``` The scaphoid (lateral) and lunate (medially) articulate with the distal radius The triquetrum articulates with the articular disc during adduction of the wrist joint ONLY The ulna DOES NOT form part of the wrist joint Joint is synovial, ellipsoid joint Movements are flexion, extension, adduction (ulnar deviation) and abduction (radial deviation) The wrist and carpal joints are secured by palmar and dorsal radiocarpal and ulnocarpal ligaments and by radial and ulnar collateral ligaments ```

Answer 170

Transverse carpal ligament forms an arch by which 9 tendons and 1 nerve pass through form the forearm into the wrist Carpal tunnel syndrome caused when this area becomes inflamed or oedematous putting pressure on the tendons and nerve in this tunnel ``` contents: flexor digitorum profundus 4 tendons flexor pollicis longus single tendon flexor digitorum superficialis 4 tendons median nerve ```

Answer 171

*Some Lovers Try Positions That They Can’t Handle* Scaphoid, Lunate, Triquetrum, Pisiform Trapezium, trapezoid, capitate, hamate You can remember that the TrapeziUM is under the thUMb

Answer 172

Collateral Ligaments found on either side of each finger and thumb joints to prevent sideways movements Strongest ligament connects proximal phalanx to intermediate phalanx on the palmar side of fingers and is called the volar plate. Prevents hyperextension

Answer 173

Many start in forearm (extrinsic muscles) Small muscles working thumb and little finger start on carpal bones Thumb area - thenar eminence: made up of four muscles. Opponens pollicis, adductor pollicis, flexor pollicis brevis and abductor pollicis brevis. Each begins at the wrist and attaches to the proximal phalanx of the thumb. Little finger palmer area - hypothenar eminence. Consists of the oppens digiti minimi, flexor digiti minimi brevis and abductor digiti minimi Intrinsic muscles arise from metacarpals extending to proximal phalanges - function to get fingers in position and hold them steady

Answer 174

median nerve supplies skin of medial two and a half fingers on dorsal side and the medial 3 and a half thumb/fingers and medial palm on the palmar side radial nerve supplies skin on dorsal thumb and medial dorsal of hand ulnar nerve supplies skin of lateral dorsal little finger and half of ring finger and same fingers on palmar side along with lateral palm

Answer 175

Superficial muscles are associated with movements of the shoulder Intermediate muscles are associated with movements of the thoracic cage Deep muscles are associated with movements of the vertebral column.

Answer 176

superficial: trapezius - accessory nerve Upper fibres: elevate scapula and rotate during abduction Middle fibres: retract scapula Inferior fibres: pull scapula inferiorly latissimus dorsi - thoracodorsal nerve extends, adducts and medially rotates upper limb levator scapulae - dorsal scapular nerve elevates scapula rhomboid major and minor - dorsal scapular nerve retracts and rotates scapula intermediate: serratus posterior superior - ICN elevates ribs 2-5 serratus posterior inferior - ICN depresses ribs 9-12

Answer 177

superficial: splenius capitis - spinal nerves C3/4 rotate head ipsilateral sides splenius cervicis - lower cervical spinal nerves rotate head to ipsilateral side ``` intermediate: erector spinae (iliocostalis, longissimus and spinalis) - posterior rami spinal nerves unilaterally flex vertebral column and bilaterally extend vertebral column ``` deep: all innervated by posterior rami spinal nerves semispinalis - extends and contra laterally rotates head and vertebral column multifidus - stabilises VC rotatores - stabilises VC and proprioceptive function

Answer 178

``` Intracapsular ligament (within joint capsule): ligament of the head of the femur runs from acetabular fossa to fovea of the femur. Encloses the obturator artery which supplies the head of the femur Extracapsular ligament (outside of joint capsules): iliofemoral arises from ASIS splits into Y shape inserting into the intertrochanteric line of the femur. This ligament is important for preventing hyperextension of the hip and is the strongest ligament Pubofemoral ligament and ischiofemoral ligaments are reinforcing for the joint capsule and helps hold head of femur into the acetabulum ```

Answer 179

Arterial supply is largely via the medial and lateral circumflex femoral arteries (branches of profunda femoris) Medial artery is the main supply and if this supply is blocked is the most probably cause of avascular necrosis of the head of the femur Joint is primarily innervated by the sciatic, femoral and obturator nerves (the same which innervate the knee - this is why hip/knee pain is often referred to the other area)

Answer 180

Flexion: iliopsoas, rectus femoris, sartorius, pectineus Extension: gluteus maximus, semimembranosus, semitendinosus and biceps femoris (HAMSTRINGS) Abduction: gluteus medius, gluteus minimus, piriformis and tensor fascia latae Adduction: adductor longus, brevis and magnus, piriformis and tensor fascia latae Lateral rotation: biceps femoris, gluteus maximus, piriformis and assisted by obturators internus and externus, gemelli and quadratus femoris Medial rotation: anterior fibres of gluteus medius and minimus, tensor fascia latae

Answer 181

innervation femoral nerve All (aside from sartorius): Extends the leg at the KNEE joint Rectus femoris also FLEXES the HIP and is the only muscle to cross both the hip and knee joint Sartorius is also a hip FLEXOR and FLEXES the knee quadriceps femoris - vastus lateralis, intermediairs and medialis and rectus femoris iliopsoas sartorius Pectineus

Answer 182

Innervation: Obturator nerve (lumbar plexus) Arterial supply: obturator artery Hip ADDUCTORS Adductor magnus also has a hamstring portion which EXTENDS the hip ``` Adductor magnus Adductor longus Adductor brevis Obturator externus Gracillis ```

Answer 183

Act to EXTEND the hip and FLEX the knee Biceps femoris also LATERALLY ROTATES the hip and knee Semitendinosus and semimembranosus also MEDIALLY ROTATE the hip and knee Hamstrings: biceps femoris, semitendinosus and semimembranosus Hamstring portion of adductor magnus

Answer 184

Largest joint in the body made of the femur, tibia and patella One of the major weight bearing joints in the body Is a HINGE SYNOVIAL joint mainly allows for flexion and extension small amount of medial and lateral rotation Unstable anatomy: contact surface between femur condyles and tibial plateaus is not supportive enough, to compensate has lateral ligaments (externally) and cruciate ligaments and menisci (internally) Stability is also dependent on hamstring muscles Menisci: makes surface deeper and more round Cruciate ligaments prevent sliding of femur and tibia ends against one another in horizontal plane blood supply - via vehicular anastomosis around the knee

Answer 185

Fibrocartilage structures that serve to deepen the articular surface of the tibia (increases joint stability) and act as shock absorbers by increasing surface area The medial meniscus is also attached to the TIBIAL COLLATERAL LIGAMENT and JOINT CAPSULE; therefore damage to the tibial collateral ligament usually causes medial meniscus damage also The lateral meniscus is smaller and has no additional attachments so is more mobile

Answer 186

MCL - stabilises hinge action and prevents medial rotation LCL - stabilises hinge action and prevents lateral rotation ACL - prevents anterior tibia dislocation PCL - prevents posterior dislocation of tibia

Answer 187

A synovial fluid filled sac found between moving structures within a joint to help lubricate and cushion movement and impact Bakers cyst is a common clinical problem: inflammation of the popliteal cyst causing pain and swelling in the back of the knee. Can often be caused by sports injuries (impact to the knee) or by osteoarthritis, inflammatory arthritis or gout

Answer 188

Extension: quadriceps femoris Flexion: hamstrings, gracilis, sartorius and popliteus Lateral rotation: biceps femoris Medial rotation: semimembranosus, semitendinosus, gracilis, sartorius, popliteus

Answer 189

proximal tibia is widened into medial and lateral condyles which aids weight bearing. They form a flat surface called the tibial plateau which articulates with the femoral condyles to form the weight bearing aspect of the knee joint. Between the two condyles is the intercondylar eminence which projects upwards and forms the main attachment of the ligaments and menisci of the knee joint and articulates with the intercondylar fossa of the femur. Distally the femur forms the medial malleolus (bony prominence on inner ankle) which articulates with the tarsal bones of the foot to form part of the ankle joint. Fibula - located within the lateral aspect of the leg, it’s main function is for muscle attachment NOT weight bearing. The proximal tibiofibular joint articulates with the lateral condyle of the tibia. The distal tibiofibular joint articulates with the fibular notch of the tibia.

Answer 190

four muscles in the anterior leg that act to dorsiflex and invert the foot and are all supplied by the deep fibular nerve. Extensor digitorum longus: also extends lateral four toes and dorsiflexes the foot Extensor hallucis longus: also extends the big toe and dorsiflexes the foot Tibialis anterior: strongest dorsiflexor muscle and causes foot inversion Fibularis tertius: may not always be present (anatomical variation) and sometimes considered part of extensor digitorum longus. Everts the foot and dorsiflexes. *foot drop occurs with damage to the common fibular (peroneal) nerve; affecting the deep fibular nerve therefore affecting all muscles of the anterior leg, producing permanent plantarflexion of the affected foot*

Answer 191

function is eversion of the foot. Innervated by the superficial fibular (peroneal) nerve. Fibularis longus: aka peroneal longus. Foot eversion as well as plantarflexion. Fibularis brevis: aka peroneal brevis. Produced foot eversion.

Answer 192

Superficial Gastrocnemius Plantarflexion of ankle and knee flexion Plantaris (absent in 10% of people) Plantarflexion of ankle and flexes the knee Soleus Plantarflexion of the ankle joint Deep Popliteus Laterally rotates the femur on the tibia allowing knee flexion (unlocks the knee joint) Tibialis posterior Inverts and plantar flexes the foot and maintains medial foot arch Flexor digitorum longus Flexes lateral four toes Flexor hallucis longus Flexes the great toe

Answer 193

Formed of the fibula articulating with the talus bone and the medial malleolus of the tibia which articulates with the talus Functionally a HINGE joint (synovial) permitting dorsiflexion and plantarflexion of the foot. Arterial supply is from malleolar branches of anterior tibial, posterior tibial and fibular arteries Innervation from tibial, superficial fibular and deep fibular nerves Two main sets of ligaments: Medial (deltoid) ligament attached to the medial malleolus, is a large fan like ligament attaching to the talus, calcaneus and navicular bones. Its primary action is to resist over-eversion of the foot. Very strong ligament that is much less likely to rupture than the lateral, if it is injured it’s likely to be a very complex injury Lateral ligaments: spans between the lateral malleolus and calcaneus and lateral and posterior aspects of the talus (3 bands). It resists over-inversion of the foot The ankle ring is the joint and ligaments of the ankle that can be visualised as a ring in the coronal plane. Upper part formed by tibia and fibula, lower by subtalar joint and sides by the medial and lateral ligaments. When a ring breaks it often breaks in TWO points and this is the same for ankle injuries. Often if there is fracture a ligament tear/rupture also present

Answer 194

tarsals: Calcaneus forms the heel bone. Has the Subtalar joint (talus and calcaneus) and calcaneocuboid joints (between calcaneus and cuboid bone) Talus forms the ankle articulation with both the femur and tibia. The subtalar joint is inferior to the talus between the talus and calcaneus. Anteriorly is the talonavicular joint between the talus and navicular bone. Navicular bone called this because it is BOAT shaped and is site of posterior tibialis tendon insertion Cuboid is the furthest lateral bone behind the 4/5th metatarsals There are THREE cuneiforms (lateral, medial and intermediate) that help shape the transverse arch of the foot and are attachment sites for muscles Metatarsals are numbered 1-5 as in the hand and join to the phalanges via MTP joints There are 3 phalanges in each toe aside from the BIG (1st) toe which only has 2 (same as the thumb in the hand) and are all connected by IP joints

Answer 195

Formed of bony floor and connective tissue roof Is a fibro-osseous space located on posteromedial aspect of ankle Acts as passageway for tendons, nerves and vessels to travel between the posterior leg and foot How to remember: Tom, Dick and a Very Nervous Harry (Tibialis posterior, flexor Digitorum longus, posterior tibial Artery and Vein, tibial Nerve, flexor Hallucis longus)

Answer 196

Extrinsic muscles from the leg and intrinsic muscles from the foot (similar to the hand) Extrinsic muscles are mainly responsible for eversion, inversion, plantarflexion and dorsiflexion of the feet Intrinsic muscles are mainly responsible for fine motor actions of the foot e.g. individual toe movements Dorsal Extensor digitorum brevis Extends medial 4 toes at MTP and IP joints Deep fibular nerve Extensor hallucis brevis Extensor of the great toe at MTP joint Deep fibular nerve ``` Plantar Superficial 1st layer: Abductor hallucis Abducts and flexes great toe Medial plantar nerve ``` Flexor digitorum brevis Flexes lateral four digits at PIP joints Medial plantar nerve Abductor digiti minimi Abducts and flexes 5th digit Lateral plantar nerve second layer: Quadratus plantae Assists FDL flexing lateral 4 digits Lateral plantar nerve Lumbricals Flexes MTP joints while extending IP joints Medial plantar nerve and lateral plantar nerves third layer: Flexor hallucis brevis Flexes proximal phalanx of great toe Medial plantar nerve Adductor hallucis Adducts great toe and forms transverse arch of foot Deep branch lateral plantar nerve Flexor digiti minimi brevis Flexes proximal phalanx of 5th digit Superficial branch of lateral plantar nerve fourth layer: Plantar interossei Adducts digits 3-5 MTP joints Lateral plantar nerve Dorsal interossei Abducts digits 2-4 and flex MTP joints Lateral plantar nerve

Answer 197

Iliohypogastric: innervates internal oblique and transversus abdominis, gluteal skin in pubic region Ilioinguinal: innervates internal oblique and transversus abdominis and skin on antero-medial thigh (penis and scrotum in males) Genitofemoral: genital branch innervates cremasteric muscle and skin of scrotum/mons pubis and labia majora. Femoral branch innervates skin on upper anterior thigh Lateral cutaneous: innervates anterior and lateral thigh down to the knee Femoral: innervates muscles of anterior thigh and skin on anterior thigh/medial leg Obturator: innervates medial thigh muscles and skin on medial thigh

Answer 198

Superior gluteal: innervates gluteus minimus, medius and tensor fascia lata Inferior gluteal: innervates gluteus maximus Sciatic: tibial portion innervates posterior thigh and muscles of posterior leg and sole of foot, skin of posterolateral leg, lateral and sole of foot. Common fibular portion innervates short head of biceps femoris, all anterior and lateral leg muscles and extensor digitorum brevis, skin of lateral leg and dorsum of foot Posterior femoral: innervates skin on posterior thigh and leg and of perineum Pudendal: innervates muscles in perineum, external urethral sphincter, external anal sphincter, lavator ani, penis and clitoris and most perioneal skin

Answer 199

``` Vulva Vagina Cervix Uterus Fallopian tubes Ovaries **BIRTH CANAL refers to the CERVIX and VAGINA** ```

Answer 200

Formation of ova (ovogenesis and ovulation) Reception of spermatozoa (intercourse/copulation) Environment for fertilisation (conception) Environment for foetal development (pregnancy) Parturition Lactation Production of oestrogen and progesterone (secondary sexual characteristics) Sexual function (female phenotype)

Answer 201

``` Breast bud growth Hip widening Fat distribution changes Protecting vascular intima Protecting bones ``` Characteristics of female reproductive system: Cyclic activity changes (menstrual cycle and menstruation) Restricted periods of fertility (ovulation) Limited gamete production (oogonia pool established at birth)

Answer 202

``` Components: Mons pubis Anterior commissure Prepuce (clitoral sheath) Clitoris Urethral meatus Hymen Posterior fourchette/commissure (area where the labia minora meet posteriorly) Labia minora Labia majora Bartholin’s glands ```

Answer 203

Fibromuscular tube 7-10cm long Has walls, four fornices and a hymen (posterior fornix is particularly important for ejaculation, found close to the pouch of Douglas) Walls have a muscle layer and mucosal layer In resting state the anterior and posterior walls are opposed Function: Passage for menstruation and uterine secretions Intercourse Birth canal Natural defence against infection for internal genitalia (inner surface bathed in acid fluid secreted from uterus or cervical glands) *CULDOCENTESIS is a procedure to check for abnormal fluid in the pouch of Douglas (rectouterine pouch) using a CULDOSCOPY*

Answer 204

Cylindrical shaped organ, 2-3cm long, anatomically a part of the uterus but physiologically distinct Mostly composed of involuntary muscle (superiorly) and fibrous connective tissue (inferiorly) - should feel firm in vaginal examination Upper ⅔ of the cervix - lined by ciliated cylindrical epithelium Lower ⅓ lined by stratified squamous epithelium Squamocolumnar junction/transformation zone - usually found at the external Os but varies depending on age, oestrogen use, pregnancy status etc. this junction is the site of cervical cancer initiation In nonpregnant women - nose. In pregnant women - lip consistency Opening (Os) can be nulliparous (circular) or parous (slit), usually is nulliparous before birth and parous after On examination, moving the cervix (cervical excitation) should NOT be painful. Can indicate EP, pelvic inflammatory disease etc. ``` Components: External cervical opening (Os) Cervical canal Internal Os Mucosa (producing natural secretions to lubricate vagina) ``` Function: Progesterone in luteal phase of cycle allows cervical secretions hospitable for sperms Acts as a closed gate during pregnancy Participates in formation of the birth canal

Answer 205

During pregnancy secretions of cervical canal become thicker and form a mucosal plug Final weeks of pregnancy - head of foetus pushes against the cervix causing signalling to brain (pituitary gland) causing oxytocin release Oxytocin carried to the uterus causing contractions and inducing parturition.

Answer 206

Pear shaped organ 8 x 5 x 3cm usually plum sized in nonpregnant premenopausal women (shrinks after menopause) Is anteverted in 80% of women (can be palpated between hands on bimanual examination unless obese, tense or full bladder), retroverted in others (fully mobile but difficult to palpate bimanually) and rarely can be axial (fails to lift out of the pelvis at 12 weeks pregnency causes uterine incarceration presenting with discomfort and urine retention). The position of the uterus determines the position of the cervix and vagina Components: Endometrium (innermost layer of epithelial cells and connective tissue with numerous glands) Myometrium (very strong but soft muscle formed of smooth muscle, is the thickest layer) Perimetrium (outer layer of uterine wall made of epithelial cells and connective tissue) Fundus Body Neck (cervix) Ligaments Function: Site of foetal development Ligaments: loosening of the uterine ligaments after menopause can lead to prolapse Cardinal (transverse cervical) Uterosacral Broad ligament (sheet like fold of peritoneum covering whole uterus) Round ligament Pubocervical

Answer 207

2 masses located in both sides of the uterus, usually not palpable however can be in pathological conditions like cysts Formed of the fallopian tubes (salpinx/oviducts), ovaires and parametria (associated connective tissue) Fallopian tubes (salpinx or oviducts): function is peristalsis and a ciliary system to transport ovum from ovaries to the uterus, takes 4 days for mature ovum/zygote to reach the uterus Fimbriae (finger like projections) Infundibulum (funnel-shaped opening of tube just above the fimbriae) Ampulla (usually place of conception and suitable point of tubal ligation) Isthmus (intramural junction with uterus) Ovaries: Size of a large grape during reproductive years Right is located slightly lower than the left Follicles (microcysts) can enlarge causing ovarian cysts (usually asymptomatic but can lead to haemorrhage or ovarian torsion) After ovulation the ovum can be absorbed by the contralateral tube Mittelschmerz (middle pain) is pain associated with ovulation around day 14 of menstrual cycle lasting a few hours to 3 days (easily misdiagnosed) Ligaments/gubernaculum: Suspensory ligament Ovarian Round ligament (exits pelvis via deep inguinal ring and continues to the labia majora where fibres spread and mix with tissue of mons pubis) Follicles: Contain primary oocyte, grow in response to hormonal stimulation Granulosa cells and theca cells support follicle growth/development

Answer 208

Ovarian arteries arising from abdominal aorta Uterine arteries arising from internal iliac (hypogastric) arteries Utero-ovarian communicating arteries

Answer 209

Menstrual cycle - refers to the cyclical changes of the ovaries and endometrium making reproduction possible. It is the combination of two cycles: Ovarian cycle - development of follicle and ovulation Uterine cycle - functional endometrium layer thickening and shedding Cycle: amount, duration, associated symptoms and cycle duration should only be compared with her own regular monthly experience Occur only in the reproductive phase of a female's life (from menarche - 1st period - around age 15 to menopause around 45 years old) Length of follicular phase varies between women and length of luteal phase is fixed at 14 days (ovulation until menses) Length of menstruation (bleeding) varies between women but is 5 days on average Stress and emotion have a very large impact on menstruation and can result in amenorrhoea Mid Cycle (14 days BEFORE next cycle begins - usually day 14 of average 28 day cycle) is time of ovulation and are the only days when the ovum is fresh and pregnancy can occur. Having sex or avoiding it around days 11-15 based on pregnancy desire can be utilised by couples

Answer 210

1st half is the follicular phase, oestrogen dominant (menstrual and proliferative phase) Ovulation 2nd half is the luteal phase, progesterone dominant (secretory phase) General overview: Before puberty GnRH is secreted constantly, after puberty it is secreted in pulses lasting around 28 days Cyclic changes in the hypothalamus secretion of GnRH and in the anterior hypophysis (pituitary) secretion of LH and FSH lead to cyclic changes of ovarian secretion of oestrogen, progesterone and inhibin. Steroid hormone secretions lead to changes in follicular development (follicular and luteal phases) and changes in the endometrium (menstrual-proliferative and secretory phases) as well as secondary hormone changes (breast tenderness, mood swings etc.)

Answer 211

Ovarian cycle: Follicular phase: weeks 1-2 of 4 week cycle Day 1 is first day of bleeding for all women (whole cycle is day 1 of bleed until next day 1 of bleed, varies normally between 20-35 days) Days 1-10 follicle theca cells develop receptors to LH and produce androstenedione Granulosa cells develop FSH receptors and produce aromatase, which catalyses androstenedione into 17-beta-oestradiol Days 10-14 granulosa cells develop LH receptors in addition Follicles grow and release oestrogen increasing systemic oestrogen concentration, leading to negative feedback on FSH production at pituitary level. As a result, some developing follicles will regress and die off while follicles with the most FSH receptors continue to grow, becoming the dominant follicle and eventually will be used in ovulation This follicle continues to secrete oestrogen causing the pituitary to become more responsive to GnRH pulsatile action from hypothalamus (oestrogen becomes a positive feedback on pituitary) leading to excessive LH and FSH secretion (LH surge) occurring a day or two before ovulation and results in release of the oocyte from the ovary into the fallopian tube uterine cycle: Follicular phase: weeks 1-2 of 4 week cycle Begins with shedding of endometrial layer (day 1 of menses) lasting roughly 5 days Followed by a proliferative phase caused by increasing oestrogen leading to thickening of endometrium, growth of endometrial glands and emergence of spiral arteries to supply more tissue. Also changes changes cervical mucus making it more hospitable for sperm, in days 11-15 of cycle

Answer 212

Ovarian cycle: Luteal phase: days 14-28 Following ovulation the follicle becomes the corpus luteum - remnant of luteinized theca and granulosa cells (have been exposed to LH and FSH surge) Corpus luteum continues to produce oestrogen and increase activity of enzyme P450scc (which converts cholesterol into progesterone) resulting in greater progesterone production compared to oestrogen production Progesterone acts as negative feedback at pituitary to reduce LH and FSH levels Inhibin also secreted from granulosa cells to inhibit also inhibiting the pituitary gland Both result in decline in oestrogen, making progesterone more prominent Uterine cycle: Luteal phase: days 14-28: After ovulation, the luteal phase begins (days 14-28) with progesterone production outweighing oestrogen production, causing the secretory phase Causes spiral arteries to grow longer and glands to increase mucus secretion making it thicker and less hospitable for sperm Over time the corpus luteum is replaced by the corpus albicans and begins to produce gradually less progesterone and oestrogen At its lowest hormone concentration, spiral arteries collapse and the functional endometrial layer “sloughs off” for menstruation, marking a new menstrual cycle

Answer 213

dry phase - days 1-3 after period sticky phase days 4-6, white/cloudy forms sticky gloss creamy phase (semi-fertile) days 7-9, creamy or cloudy thick mucus clear phase (fertile window) days 10-14, stretchy and slippery mucus

Answer 214

Primordial follicles each contain a primary oocyte surrounded by the outer basal lamina layer Primordial follicles grow to become primary follicles during the follicular phase and consist of three layers - primary oocyte, zona pellucida (materials secreted by granulosa cells) and granulosa cells As they grow they develop a further layer called the theca folliculi which secretes androgen hormones Secondary follicles develop once they have established FSH receptors Antral follicles develop once a single large fluid filled area within the granulosa cells called the antrum develops. The antrum fills with increasing amounts of fluid, making the follicle expand rapidly. The corona radiata is made of granulosa cells and surrounds the zona pellucida and oocyte At this point, one follicle becomes dominant. Other follicles start to degrade, while the follicle grows into a mature follicle. This bulges through the wall of the ovary. Ovulation: LH surge from the pituitary causes smooth muscle of the theca externa to contract and the follicle to burst. Follicular cells release digestive enzymes to puncture a hole in the wall of the ovary, at which point, it is floating in the peritoneal cavity It is quickly swept up by the fimbriae of the fallopian tubes Corpus luteum: Leftover parts of the follicle collapse and turn yellow, becoming the corpus luteum Cells of the granulosa and theca interna become luteal cells, secreting progesterone The corpus luteum persists in response to human chorionic gonadotropin (HCG) from a fertilised blastocyst when pregnancy occurs If this HCG signalling does not occur then the corpus luteum degenerates after 10-14 days

Answer 215

Puberty begins at 8-14 years old (females) and 9-15 (males), overweight children tend to enter puberty earlier due to aromatase being present in adipose tissue (important for converting oestrogen into 17-beta-oestradiol) May be delayed puberty in girls with low birth weight, chronic disease, eating disorders, athletes etc. Puberty begins with breast buds, followed by pubic hair and finally onset of menses (menarche) which usually start around 2 years after puberty begins Hormonal changes: GH increases initially causing growth spurt Hypothalamus starts to secrete GnRH initially during sleep then throughout the day in later stages Stimulates FSH and LH release stimulating oestrogen and progesterone production FSH levels plateau about a year before menarche LH levels continue to rise and spike just before they induce menarche

Answer 216

Stage of pubertal development can be determined using this scale, based on examination of findings of secondary sexual characteristics I - aged <10 - No pubic hair - No breast development II - ages 10-11 - Light and thin PH - Breast buds form behind areola III - ages 11-13 - Course and curly PH - Breast begins to elevate beyond areola IV - ages 13-14 - Adult like but not reaching thigh PH - Areolar mound forms and projects from surrounding breast V - ages >14 - Hair extending to medial thigh PH - Areolar mounds reduce and adult breasts form

Answer 217

In first weeks of urogenital development all embryos have two pairs of ducts - mesonephric (Wolffian) and paramesonephric (Mullerian) ducts First stage of gonadal development it is impossible to distinguish sex Gonads begin as genital ridges derived from mesoderm and epithelium, initially not containing any germ cells In fourth week germ cells begin to migraine from endoderm lining of the yolk sac to the genital ridges via the dorsal mesentery of the hindgut Reach the genital ridges by the sixth week Simultaneously the epithelium of the genital ridges proliferates and penetrates the intermediate mesoderm to form primitive sex cords. This is the indifferent gonad

Answer 218

XY chromosome present. Y chromosome contains the SRY gene, stimulating primitive sex cords to form testis (medullary) cords The tunica albuginea (fibrous connective tissue) forms around the cords Portion of the testis cords breaks off to form the future rete testis and the remaining forms either germ cells or sertoli cells In puberty these cords acquire a lumen and become seminiferous tubules (site of sperm production) Located between the testis cords are Leydig cells. In the eight week they produce testosterone causing differentiation of internal and external genitalia Mesonephric ducts develop in presence of testosterone, giving rise to efferent ductules, epididymis, vas deferens and seminal vesicles while the mullerian duct degenerate due to presence of anti-mullerian hormone (produced by sertoli cells) leaving the remnant appendix testis located either side on upper pole of each testis

Answer 219

XX chromosomes with no SRY gene present. Primitive sex cords degenerate and no testis cord is formed Epithelium of gonad proliferates, producing cortical cords In the third month these break up into clusters surrounding each oogonium with a layer of follicular cells (primordial follicles form) No leydig cells therefore no testosterone production. Mesonephric ducts degenerate leaving the remnant Gartner’s duct Absence of anti-mullerian hormone allows mullerian ducts to develop into the fallopian tubes, uterus, cervix and upper ⅓ vagina Lower ⅔ formed by the sinovaginal bulbs from the urogenital sinus

Answer 220

Embryonic stage consists of the first 8 weeks of development A week after fertilisation the blastocyst differentiates into various cell types. Embryoblast cells split into two with the yolk sacs on one side and the amniotic cavity on the other. The embryonic disc sits (becomes the fetal pole and eventually into the foetus) between the yolk sac and the amniotic cavity. The chorion surrounds this complex, it has two layers (cytotrophoblast and syncytiotrophoblast) Chorionic cavity forms around the yolk sac, embryonic disc and amniotic sac. These structures are suspended from the chorion by the connecting stalk, which will eventually become the umbilical cord. At week 5 the embryonic disc develops into the foetal pole containing the ectoderm, mesoderm and endoderm which eventually differentiate into different body tissues At week 6 the foetal heart forms and begins beating. The spinal cord and muscles also start to develop. The foetal pole is around 4mm long At 8 weeks all major organs have started development Foetal stage: Weeks 9-40 of pregnancy Develops organs, bones etc.

Answer 221

Just before ovulation the primary oocyte undergoes meiosis (splitting 46 into 23 chromosomes becoming a haploid cell) leaving 23 chromosomes in the cell and 23 to form a polar body This is then a secondary oocyte Ovum is surrounded by the zona pellucida and granulosa (making the corona radiata) within the follicle When sperm enter they attempt to penetrate the corona radiata and zona pellucida to fertilise the egg Once penetrated a Ca wave makes the egg impenetrable to other sperms, within the egg the 23 chromosomes multiple to become 46 again, 23 going off to form a second polar body Zygote-blastocyst: Made from 23 egg and 23 sperm chromosomes called a zygote. Divides rapidly to create a mass of cells called the morula (3-4 days post fertilisation - end of cleavage stage). During this, the mass travels along the fallopian tube towards the uterus. The morula divides more to become the blastocyst (4-5 days post fertilisation) which is a hollow ball of cells. A fluid filled cavity within the cells develops as it travels alongside the embryoblast (cells in the middle) called a blastocoel Surrounding the embryoblast and blastocoel is an outer layer of cells called the trophoblast (will become the placenta) At this point it gradually loses the corona radiata and zona pellucida. When the blastocyst enters the uterus it contains 100-150 cells * Monozygotic (identical) twins are formed when the morula splits into two forming two embryos. * Dizygotic (fraternal) twins occur when two oocytes are released and fertilised by two different sperm.

Answer 222

Blastocyst arrives at the uterus 8-10 days after ovulation and reaches the endometrium, cells of the trophoblast undergo adhesion to the stroma (supportive layer of endometrium). The outer layer of the trophoblast is called the syncytiotrophoblast and forms projections into the stroma. Stroma cells convert into tissue called the decidua - specialised in providing nutrients to the trophoblast When the blastocyst implants on the endometrium, the syncytiotrophoblast starts to produce HCG, which sustains the corpus luteum in the ovary allowing continued production of progesterone and oestrogen

Answer 223

endoderm - GIT, lungs, liver, pancreas, thyroid, reproductive system mesoderm - heart, muscle, bone, connective tissue, blood and kidneys ectoderm - skin, nails, teeth, hair, CNS

Answer 224

During the follicular phase of the menstrual cycle, the myometrium grows spiral arteries into the endometrium When the blastocyst implants into the endometrium the syncytiotrophoblast grows into the endometrium forming chorionic villi, containing foetal blood vessels. The chorion frondosum is an area containing mesoderm cells and is the most vascular area of the chorionic villi. This area proliferates to become the placenta Trophoblast invasion of the endometrium sends signals to the spiral arteries reducing their vascular resistance and increasing blood flow; eventually they break down leaving pools of blood called lacunae. Lacunae form at around 20 weeks gestation. Maternal blood flows from the uterine arteries into these lacunae and back out through the uterine veins. Lacunae surround the chorionic villi separated by the placental membrane. Oxygen, CO2 and nutrients diffuse across this membrane between maternal and foetal blood Sometimes if the lacunae do not form adequately then preeclampsia can occur (high vascular resistance in spiral arteries leading to maternal HTN and complications)

Answer 225

Respiration and gaseous exchange and acid-base homeostasis nutrition (mostly glucose) excretion producing urea and creatinine endocrine - hCG to maintain corpus lute (can cause trimester 1 N+V symptoms Oestrogen for softening tissues increasing flexibility allowing muscle and ligaments to expand ready for birth and preparing breasts for breastfeeding progesterone to maintain pregnancy and endometrium (side effects of reflux, constipation, hypotension, headaches, skin flushing) increases body temp by 0.5-1 degree immunity - maternal antibodies providing short term protection from infections

Answer 226

Anterior pituitary gland produces more ACTH, prolactin and melanocyte stimulating hormone Higher ACTH - more steroid hormones (cortisol and aldosterone) leading to improved autoimmune conditions and susceptibility to diabetes and infections (decreased immunity) Increased prolactin - suppresses FSH and LH Increased melanocyte stimulating hormone - increased pigmentation (linea nigra and melasma) TSH - normal but T3 and 4 INCREASE HCG - rise, doubling every 48 hours until plateau around 10-12 weeks (cause N+V symptoms in trimester 1) Progesterone - rises throughout pregnancy, maintains pregnancy, prevents contractions, suppresses maternal immune response to foetal antigens Oestrogen - rises throughout produced by placenta. Has side effects of increasing risk of bacterial and candidal infections

Answer 227

Uterus increases from 100g to 1.1Kg via hypertrophy of myometrium and blood vessels (due to increased oestrogen) Cervix - Increased oestrogen may cause cervical ectropion and increased cervical discharge. Before delivery prostaglandins break down collagen in the cervix allowing dilation and efface during labour Vagina - increases hypertrophy of vaginal muscles preparing for delivery

Answer 228

Increased blood volume Increased placental volume Increased CO (SV and HR) Decreased peripheral vascular resistance Decreased BP in early and mid pregnancy returning to normal by term Varicose veins from peripheral vasodilation and obstruction of IVC by uterus Peripheral vasodilation causing flushing and hot sweats

Answer 229

resp: Tidal volume and respiratory rate increase in later pregnancy to meet increased oxygen demands renal : Increased blood flow to kidneys Increased eGFR Increased aldosterone increases salt and water retention (oedema) Increased protein excretion from kidneys (<0.3g in 24 hours) Dilatation of ureters and collecting system leading to physiological hydronephrosis (more right sided)

Answer 230

Increased RBC production leading to iron, folate and B12 increased needs (up to 40% increase, fluid retention causing swelling) Plasma volume increases more than RBCs, leading to lower concentration of RBCs (anaemia) Clotting factors (fibrinogen and factors VII, VIII and X) increase making a pro-coagulable state (increase VTE risk) Increased WBCs Decreased platelet count Increased ESR and DDIMER Increased alkaline phosphatase (ALP) up to 4 x normal from placental secretion Reduced albumin due to protein loss in kidneys Calcium requirement increases as does gut absorption of calcium (remains stable)

Answer 231

Increased skin pigmentation (increased melatonin) Striae gravidarum (stretch marks) General pruritus (normal or indicates obstetric cholestasis) Spider naevi Palmar erythema Postpartum hair loss is normal and usually improves after 6 months

Answer 232

Normally occurs between 37-42 weeks of gestation Three stages: Onset of labour (true contractions) until 10cm cervical dilation expulsion - 10cm dilation to delivery of the baby Placental delivery - Delivery of the baby to delivery of the placenta

Answer 233

braxton-Hicks contractions: Occasional, irregular contractions of the uterus Usually felt during the 2nd and 3rd trimester causing tight cramping Not true contractions and are not the start of labour, they will NOT progress and become regular Staying hydrated and relaxing can help reduce their frequency or intensity Labour onset: Act like local hormones triggering contraction in uterine muscles and help ripen the cervix (break down collagen) for delivery. Key prostaglandin is E2. Pessaries of E2 (dinoprostone) can be used to induce labour if needed. Oestrogen secretion increases, increasing cortisol production (to increase oestrogen further) and inducing myometrium to develop receptors for oxytocin and induces formation of gap junctions in smooth muscle of the uterus to allow simultaneous contraction needed for birth. Near the time of labour, foetal cells release oxytocin stimulating release of prostaglandins from the placenta. A positive feedback loop of oxytocin and prostaglandins begins inducing and maintaining uterine contractions (labor initiating) Often the mucus plug at the Os may fall away causing blood and mucus discharge, or the amniotic sac may rupture causing “waters to break”. These both can trigger true labour contractions

Answer 234

Onset of labour (true contractions) until 10cm cervical dilation Cervical dilation and effacement (thinning from front to back) The show - mucus plug preventing bacteria - falls out and creates space for infant to pass through Three phase: Latent: from 0-3cm cervical dilation. Progresses around 0.5cm per hour. Irregular contractions Active phase: 3-7cm dilation. Progresses at around 1cm per hour and has regular contractions Transition phase: 7-10cm dilation. Progresses around 1cm per hour and shows strong, regular contractions (every 2-5 mins apart)

Answer 235

Expulsion - 10cm dilation to delivery of the baby Three Ps Power: strength of uterine contraction Passage: size and shape of the passageway - mainly the pelvis Passenger: 4 descriptive qualities of the foetus: Size - particularly the head Attitude [posture], e.g. how the back is rounded and how head and limbs are flexed Lie [position in relation to mothers body] can be longitudinal [straight up and down], transverse [straight side to side] or oblique [at an angle] Presentation: part of the foetus closest to the cervix Cephalic - head first Shoulder Breech (legs first) can be complete (hips and knees flexed), frank (hips flexed knees extended) or footling (foot hanging through cervix)

Answer 236

Engagement Descent: described by baby's head in relation to mother ischial spines; measured in cm. -5cm when baby is high up around pelvic inlet, 0 when “engaged”, +5 when foetal head has descended further out Flexion: foetal chin against chest Internal rotation: foetal shoulder rotate 45 degrees to align with widest part of pelvic inlet Extension: foetal head extends Restitution and external rotation: head externally rotates to pass shoulders out Expulsion: anterior and posterior shoulder followed by the rest of the body is delivered

Answer 237

Delivery of the baby to delivery of the placenta Uterus contracts to separate the placenta from the uterine wall and carefully remove all parts. management: Physiological management - placenta delivered by maternal effort without medication or cord traction Active management of 3rd stage - HCP assists delivery, shortened 3rd stage reducing risk of haemorrhage or >60 minute delay in placenta delivery. Can be associated with N+V/ involves giving IM oxytocin to help the uterus contract and expel the placenta. Careful traction is applied to the umbilical cord guiding the placenta out

Answer 238

Surface anatomy: Circular body: largest part Axillary tail: smaller, runs along inferior edge of pec major toward axillary fossa. Nipple at the centre: mostly made of smooth muscle fibres, surrounding area is pigmented area called the areolae containing numerous sebaceous glands (enlarge during pregnancy secreting oily substance acting as protective lubricant) Structure: Mammary glands: modified sweat glands consisting of a series of ducts and secretory lobules (15-20). Each consists of many alveoli drained by a single lactiferous duct, which converge at the nipple Connective tissue strome: supporting structure surrounding the glands (fibrous and fatty component). The fibrous stroma condense to form suspensory ligaments (of Cooper) with function to attach and secure the breast to the pectoral fascia and separate the secretory lobules of the breast. Retromammary space: layer of loose connective tissue between the breast and pectoral fascia, often used in reconstructive plastic surgery Blood supply: Medial aspect via the internal thoracic artery (internal mammary artery) - branch of the subclavian Lateral part via the lateral thoracic and thoracoacromial branches (axillary artery origin), lateral mammary branches (PCA origin) and mammary branch (origin anterior ICA) Veins correspond with arteries and drain into the axillary and internal thoracic veins Lymphatics: Three groups of lymph nodes receiving lymph from breast tissue - axillary (75%) - comprised of the humeral/lateral, central, apical, subscapular and pectoral lymph nodes - ``` parasternal nodes (20%) and posterior intercostal nodes (5%) Also receives drainage from the skin (drains into axillary, inferior deep cervical and infraclavicular nodes) and nipple/areola (drains into subareolar lymphatic plexus) ``` Nerve supply: Innervated by anterior and lateral cutaneous branches of the 4-6th ICN Contain both sensory and autonomic nerve fibres

Answer 239

Three major shunts: Ductus venosus: umbilical vein and IVC, becomes round ligament after birth Foramen ovale: between RA and LA, becomes fossa ovalis after birth (ASD if remains) Ductus arteriosus: between pulmonary artery and aorta, becomes the ligamentum arteriosus (PDA if remains) Lungs are not oxygenated Right heart is dominant side One umbilical vein delivers more oxygenated blood (great vein - towards the heart) Two umbilical arteries drain deoxygenated blood to the placenta for gaseous exchange

Answer 240

Three parts of the ear: External Middle (tympanic cavity) Internal (inside bony labyrinth) Function: External and middle ears have a role in hearing Internal ear is the main centre of hearing and balance The inner ear can receive vibrations of the sound through the middle and external ear route or through the skull (can insert hearing aids into teeth)

Answer 241

``` Pinna or auricle is the outside part of the ear, the framework of elastic cartilage covered by skin External auditory canal or tube - about 3,5cm long consists of cartilaginous part (curved and lies at an angle to the bony part and narrows medially to protect the eardrum from trauma) and inner bony part. Tympanic membrane (eardrum) This cavity is air filled, connected to air via the external canal ```

Answer 242

tympanic cavity Ossicles: 3 of the smallest bones in the body transmit the sound waves from the tympanic membrane to the inner ear, these are the malleus, incus and stapes. Eustachian tube (ET) is a canal linking the middle ear with the pharynx, helping to equalise pressure in the middle ear. This is needed for proper transfer of sound waves. The tube is lined with mucosa like the inside of the nose and throat Various nerves contribute and pass via the middle ear such as the facial nerve (CN VII) and branches of the glossopharyngeal nerve (CN IX) making the middle ear very sensitive to pathologies This cavity is air filled, connected to air via the eustachian tube/pharyngotympanic tube

Answer 243

Most of the time this tube is closed, but during physiologic manoeuvres it is opening (swallowing, chewing, yawning, valsalva, Muller, sneezing etc.) The orifice of the ET is located within the pharynx and middle ear In children, enlargement of the adenoids may block this orifice causing blockage or malfunction of the ET producing otitis media

Answer 244

Cochlea contains the receptors and nerves for hearing Vestibular system of the vestibule (contains receptors and nerves for balance) and the semicircular canals/ducts (contain receptors for balance) The main nerve here is the vestibulocochlear nerve (CN VIII) for balance and hearing This canal is fluid filled

Answer 245

The normal oily secretion in the ear canal which is toxic for insects and keeps the canal clean If this becomes dry and impacted it can lead to tinnitus, poor hearing, dizziness, earache, fullness of the ear etc.

Answer 246

Transmission of air vibrations from the external and middle ear (Compression hits the tympanic membrane causing force transference to the stapes bone, then to the oval window of the inner ear) Converting these vibrations into electrical signals in the inner ear (The hair cells are stimulated by mechanical force of the ear vibrations. The apex of the hair cell is bathed in high potassium while the base in low potassium creates a natural gradient for electrical impulses therefore converting mechanical energy into electrical and transmitting action potential from the inner ear to the brain from processing of the sound). Transfer of these signals into the cortex via CN VIII and auditory pathways Interpretation and conception of sound in the auditory cortex in the temporal lobe The cochlear contains the organ of corti, a snail shaped organ responsible for reception of hearing. Hair cells detect mechanical change produced by air conduction through the ear There are inner (afferent) and outer (efferent) hair fibres Tip Links are thought to amplify sound

Answer 247

Detects motion, head position and spatial orientation. Main components in the inner ear called the vestibular labyrinth, continuous with the cochlear 3 semicircular bones situated in a plane of head movement

Answer 248

The inner ear contains three semicircular canals (lateral, posterior and superior) Each canal is responsible for detecting a certain head positioning Each canal is filled with fluid (endolymph) and displacement of the fluid is used to determine which position the head is in as the fluid flows into the ampulla. The ampulla contains hair cells and stereocilia. Endolymph passing into this causing movement and therefore electrical impulse conduction Nerve signals are sent to the brain in response to fluid displacement The posterior detects when the head tilts down towards the shoulder (ear to shoulder) The superior detects nodding up and down motion (yes) The lateral detects shaking side to side motion (no) The dix hallpike maneuver is used to determine if dizziness is caused by inner ear pathology, laying the patient supine, turning their head to the right 45 degrees and extending the head around 20-30degrees - observing for nystagmus confirms a pathology in the right inner ear (condition called BPPV) and depending on pathology maneuvers can be performed to cure the dizziness

Answer 249

Otolith organs detect forward and backward movements and gravitational forces The utricle detects movement in the horizontal plane The saccule detects vertical movements The movement is detected via displacement of hair cells following movement of a top layer of calcium carbonate crystals called otoconia, causing movement of subsequent layers and ultimately displacement of recepting hair follicles.

Answer 250

Nasopharynx - nostrils, vestibule and choana Septum and lateral walls Respiratory mucosa and olfactory mucosa Cyclic erection Concha (turbinates): superior, middle and inferior - meatuses (between conchae) Vascular supply, little’s area (Kiesselbach’s plexus) on the septum Paranasal sinuses and their orifices ``` Function: Refining air Warming air Moisturising air Smelling air ```

Answer 251

Nasal concha or turbinate is a long, narrow, curled shelf of bone protruding into the breathing passage of the nose Turbinates are enriched with airflow pressure and temperature sensing nerve receptors linked to the trigeminal nerve route (CN V) Allows for erectile capabilities of nasal congestion and decongestion in response to weather and changing needs of the body The cycle of partial congestion and decongestion is called the nasal cycle Every few hours, one nostril will partially congest itself while the other decongests and breathing occurs mainly via the open nostril for the proceeding few hours, then the cycle switches and repeats.

Answer 252

Anterior supply from the anterior ethmoid artery, sphenopalatine, facial and superior labial artery anastomosis to form Kiesselbach’s plexus This is usually the site of epistaxis, common in children, less severe, seen easily with rhinoscopy and is more simple to treat The posterior vascular supply from the posterior ethmoid artery and sphenopalatine artery is less common, more serious and usually in the elderly.

Answer 253

Four paired, air filled spades inside the skull, around the nose All drain into the nasal cavity (ostiums) All covered by respiratory tract mucosa with mucociliary clearance The frontal, maxillary and anterior ethmoidal sinuses all open into the middle meatus (between inferior and middle concha) Sphenoid sinus drains into the posterior roof The nasolacrimal duct drains tears from the eye and opens into the inferior meatus (between inferior concha and floor of nasal cavity) Frontal and maxillary - can be manually examined Ethmoid and sphenoid - are deep and need imaging to be examined

Answer 254

``` Lips Buccal mucosa (lining of cheeks and lips) Floor of mouth under the tongue Hard palate Soft palate and uvula Front ⅔ of the tongue (basal ⅓ is part of the oropharynx) Frenulum (below tongue) Gums (gingiva) and teeth ```

Answer 255

posterior motor - CN X Anterior motor - CN XII, sensory posterior CN IX for touch and taste, sensory anterior CN V touch and VII taste

Answer 256

Hollow tube about 5 inches long, starting behind the nose and continuing to the oesophagus Has three parts: nasopharynx, oropharynx and hypopharynx/laryngopharynx Nasopharynx - behind the nose (choana), between the base of the skull and upper surface of the soft palate , extending in a plane superior to the hard palate from the choana to the posterior nasal cavity to the posterior pharyngeal wall. Includes the fossa of Rosenmuller, the eustachian tube orifices and site of the adenoid pad.

Answer 257

consists of four tonsillar structures (namely, the pharyngeal, tubal, palatine and lingual tonsils) as well as small collections of lymphatic tissue disbursed throughout the mucosal lining of the pharynx (mucosa-associated lymphoid tissue, MALT).

Answer 258

3 major pairs of glands: parotid (largest), submandibular/wharton’s duct, sublingual gland The parotid gland has the facial nerve and its branches pass through and divide the gland into the superficial and deep lobes The parotid gland opens into the mouth via Stensen’s duct (opposite the second upper molar tooth parallel to the line of the tragus to the corner of the lip) As well as minor salivary glands (roughly 800 smaller glands distributed throughout the upper aerodigestive tract) All are exocrine glands producing saliva Larger glands make thinner saliva and minor secrete thicker saliva

Answer 259

Cartilaginous voice box, including muscles and ligaments above the trachea Located between the hyoid bone (horseshoe shaped) and cricoid ring Epiglottis - prevents aspiration Thyroid cartilage - adam’s apple Vocal cords found between arytenoid cartilages and the anterior commissure Recurrent laryngeal nerve (vagal branch) innervates all laryngeal muscles aside from the cricothyroid muscle Superior laryngeal nerve (from vagus) innervates the cricothyroid muscle Membranes - thyrohyoid and cricothyroid are main two membranes

Answer 260

Three layers of the eye: Outer layer: sclera and cornea - fibrous and protects other layers Middle layer: uvea - vascular and includes choroid, ciliary body and iris Internal layer: retina - senses light, converts this to electrical activity and sends this to the brain Two segments: Anterior: aqueous humour - includes the anterior chamber (in front of the pupil) and posterior chamber (behind pupil) contains watery liquid Posterior: vitreous humour - includes the vitreous chamber, contains gel like material

Answer 261

Sclera: White outer layer that maintains the shape of the eye External eye muscles are attached to the sclera Sclera includes the cornea Cornea: Part of the sclera Clear, transparent avascular tissue Cone shaped allowing refraction of light, so it passes through the pupil and lens, focussing on the retina (focussing power is 60% cornea and 40% lens) Located anteriorly allowing light to pass but acts as a barrier protecting against infections Contains aqueous humour Cornea has three layers: epithelium, stroma and endothelium. Epithelium heals very quickly (within 24 hours) and damage will not affect vision, but the other two do not. If the stroma is damaged then scarring will occurring causing vision cloudiness Endothelium functions to keep the cornea dry to keep vision clear. When malfunctioning or swollen, vision becomes cloudy. Corneal epithelium is kept dry to maintain Corneal reflex is controlled by CN V and VII Difference between cornea and lens - lens is flexible and changes diameter.

Answer 262

Part of the choroid, a coloured muscle surrounding the pupil Contains circular and straight muscles The pupil is a window for light and the iris controls the diaphragm around it Miosis - pupillary constriction Mydriasis - pupil dilation *sunglasses that do not cover UV lead to mydriasis and can cause cataracts in later life* Light reflex is controlled via the CN II and III The lens is located behind the pupil, between the anterior and posterior chambers and is suspended by the ciliary system. It is transparent and flexible

Answer 263

Ciliary body - ciliary muscles laterally, ciliary processes located medially and ciliary zonules/suspensory ligaments of lens/zonular fibres hold the lens in place Ciliary processes secrete aqueous humour into the posterior chamber, which then flows through the pupil into the anterior chamber Ciliary muscles keep the lens suspended by the ciliary zonules The muscles change the diameter of the lens during the accommodation reflex Contraction of the ciliary muscle releases the zonular fibres, leading to the lens widening/accomodated (more biconcave, concentrating light in retina) in response to objects coming closer to the eye. Relaxation of the muscles flattens the lens/unaccomodated in response to objects further away The shorter the ciliary muscle contraction, the better for the eye

Answer 264

Made mainly of crystal proteins A flexible structure, diameter is changed by the zonule pulling and contraction/relaxation of ciliary muscles Lens plays a major role in accommodation (CN III) Myopia - short-sighted Hyperopia - far-sighted; visual images come into focus behind the retina making vision better for distant objects rather than near. Near point - where the eye is looking when maximally accomodated

Answer 265

Inner layer of the eye globe Has ten layers Oxygenation from the choroid posteriorly and the central retinal artery and its branches anteriorly Pigmented layer (retinal pigment epithelium RPE) is outside the neurosensory retina and nourishes the retinal visual cells. It is firmly attached to the underlying choroid Neural layer contains neurosensory retina (rods, cones and bipolar neurons) Rods - black, white and grey vision, are very light sensitive so are mostly used in dim/dark lighting also, more sensitive to light than cones (x ~500) Cones - colour vision, 3 types of cones are green, red and blue, each responds to different light wavelengths on a gradient resulting in colours we can visualise, good lighting is needed for colour vision as cones are less light sensitive. Bipolar nerves - located above the other layers and make the optic nerve for transmission of light signals to the brain

Answer 266

Object in question reflects the sun's light off of it, when looking directly at the object the light being reflected hits the cornea of our eye. The cornea biconcave surface narrows the light concentrating it into the anterior eye. The lens further refracts the light into the vitreous chamber and onto the retina Light passes through the upper layers of the retina to activate rods and cones especially in the fovea where rods and cones are most concentrated. The signal passes the retina in reverse direction to reach the optic nerve pathways including the optic chiasma Signals enter the visual cortex in the occipital area of the brain and are processed

Answer 267

maximum concentration of photoreceptor cells and the centre of our view, the fovea is located in the macula. It is the area where the sharpest vision can be achieved. Light directed onto the fovea creates sharp good vision, for good colour perception and vision clarity you must look directly at an object to protect light onto the fovea.

Answer 268

The optic disc is devoid of rods and cones, making a blind spot in our vision (the place where the optic nerve leaves the eye) The disc cup is a small dimpling in the centre of the optic disc

Answer 269

Retinal image is reversed and rotated by the brain The brain also refines the retinal image making it more vivid and clear The occipital cortex is the main organ of vision Binocular vision created by the brain from having two eyes. The brain calculates the difference between the view of each eye and creates depth conception (3D vision)

Answer 270

Protects the eye surface from dust and other harmful substances as well as extreme light Allows eyes to rest during sleep Keeps the eye surface clean, moist and lubricated without blocking vision (continuous blinking) Lubrication produced from the lacrimal glands and mucus form the conjunctiva Eyelid has 5 layers: skin, superficial fascia, orbicularis oculi (palpebral fibres), tarsal plate and palpebral fascia and the conjunctiva The conjunctiva lines the ocular surface aside from the cornea. It had the bulbar aspects that lines the sclera and the palpebral conjunctiva lining the inner aspects of the eyelid Conjunctiva has specialised tear cells helping lubricate the eye and help fight off infection Tears - produce smooth eye surface for clear vision, provide oxygen and nutrients to tissues, contain enzymes and proteins like Igs and lysosome to ward off infection

Answer 271

Located at top part of outer orbit Important for reflexive tears production (allergies or crying) Drains via two drains called punctums. Located in upper lid and other in lower lid closer to the nose Enter the punctums, flow through into the lacrimal sac and through the nasolacrimal duct into the throat 3 types of tears: basal, reflex and psychic, all released by the same gland. Each type has a slightly different composition Basal - always present in the eye ensuring the cornea is lubricated and nourished and keeping the cornea clear to sharpen vision. Its composition contains natural antibiotics preventing infection Reflex - secreted in response to external stimuli such as allergens, dust etc. producing excess basal tears in order to protect the eye from foreign substances by washing out factors causing discomfort Psychic - more protein (lactoferrin, lysozyme, IgA and IgG and albumin and hormones that act as natural analgesics/release of stress-inducing hormones built up from emotional stresses.

Anatomy Flashcards

(295 cards)