Thorax

Question 1

What are the contents of the superior mediastinum?

Answer 1

thymus, phrenic nerves, aortic arch: great veins (brachiocephalic trunk, right subclavian and r common carotid; left subclavian and left common carotid, left and brachio, left and right subs, left and right common carotids), main lymphatic trunks (thoracic), vagus nerve, great arteries, trachea and main bronchi, upper oesophagus

superior mediastinum runs from superior thoracic aperture bordered by clavicle, level of t1/2; to t4/5 transverse throacic plane, marked by sternla engal

BATS & TENT

Brachiocephalic veins
Arch of aorta
Thymus
Superior vena cava

Trachea
Esophagus
Nerves (vagus & phrenic)
Thoracic duct

(and main broc=nchi, )

Question 2

What are the two great veins?

Answer 2

The superior and inferior venae cavae*

Question 3

List the true ribs

Answer 3

1-7

True ribs attach directly to sternum

Question 4

8List the false rib

Answer 4

8-12

False ribs do not attach to sternum directly

Note also 11 and 12 (Sometimes 10) are floating. 8-10 (usu.) connect via costal cartilages ofribs above.

Floating ribs insert into the muscles of the posterior abdominal wall

Question 5

What are the components of the intervertebral disc?

Answer 5

• Annulus fibrosus
• Nucleus pulposus

see footnote:

https://www.physio-pedia.com/Intervertebral_disc

The intervertebral disc (IVD) is important in the normal functioning of the spine. It is a cushion of fibrocartilage and the principal joint between two vertebrae in the spinal column. There are 23 discs in the human spine: 6 in the cervical region (neck), 12 in the thoracic region (middle back), and 5 in the lumbar region (lower back).

They consist of three major components: the inner, nucleus pulposus (NP), the outer, annulus (AF) and the cartilaginous endplates that anchor the discs to adjacent vertebrae.

Nucleus pulposus sits at centre, It is made of 66% to 86% water with the remainder consisting of primarily type II collagen (it may also contain type VI, IX, and XI) and proteoglycans.

AF: Consists of “lamellae” or concentric layers of collagen fibres [2]. The fibre orientation of each layer of lamellae alternate and therefore allow effective resistance of multidirectional movements. The AF contains an inner and an outer portion. They differ primarily in their collagen composition. While both are primarily collagen, the outer annulus contains mostly type I collagen, while the inner has predominantly type II

Question 6

List the anatomical structures of the thoracic cavity

Answer 6

a million…
ribs
lungs and pleura
heart, pericardium/sac
diaphragm
vessels: all the biggies including azygos, hemiazgos, and accessory hemiazygos
thymus
vagus, phrencu, l recurrent laryngeal,
vertebrae
oesophagus
aorta(thoracic)

Question 7

List and describe the structures of the mediastinum

Answer 7

see fill in blank for answers

Question 8

Describe the structure of the heart

Answer 8

see fill in blanks for layers
Atria: two
Ventricles: two

Question 9

Describe the structure of the lungs

Answer 9

R and L
superior, middle (hor)/oblique/inferior

superior/oblique/inferior

Hilum: bronchus, R and L, pulmonary arteries, veins, phrenic nerve

Apex

Base
Costodiaphragmantic recesses, costopherenic angles

Cardiac notch

Surrounded by visceral and parietal pleura

The three surfaces of the lung include the costal, medial, and diaphragmatic surfaces. The costal surface is covered by the costal pleura and is along the sternum and ribs. It also joins the medial surface at the anterior and posterior borders and diaphragmatic surfaces at the inferior border. The medial surface is divided anteriorly and posteriorly. Anteriorly it is related to the sternum, and posteriorly it is related to the vertebra. The diaphragmatic surface (base) is concave and rests on the dome of the diaphragm; the right dome is also higher than the left dome because of the liver.

Question 10

Describe the connections between the heart and the lungs

Answer 10

Pulmonary circulation is the system of transportation that shunts de-oxygenated blood from the heart to the lungs to be re-saturated with oxygen before being dispersed into the systemic circulation. Deoxygenated blood from the lower half of the body enters the heart from the inferior vena cava while deoxygenated blood from the upper body is delivered to the heart via the superior vena cava. Both the superior vena cava and inferior vena cava empty blood into the right atrium. Blood flows through the tricuspid valve into the right ventricle. It then flows through the pulmonic valve into the pulmonary artery before being delivered to the lungs. While in the lungs, blood diverges into the numerous pulmonary capillaries where it releases carbon dioxide and is replenished with oxygen. Once fully saturated with oxygen, the blood is transported via the pulmonary vein into the left atrium which pumps blood through the mitral valve and into the left ventricle. With a powerful contraction, the left ventricle expels oxygen-rich blood through the aortic valve and into the aorta

Pulmonary arteries Right ventricle -> pulmonary trunk -> right and left pulmonary arteries
Purpose: deliver deoxygenated blood to the respective lung

Pulmonary veins Lung capillaries -> 4 pulmonary veins (2 from each lung) -> left atrium
Purpose: deliver oxygenated blood to the left ventricle which will distribute it to the body

Question 11

List the great vessels

Answer 11

The large arteries and veins directly connected with the heart are termed the great vessels, consisting of the inferior vena cava, superior vena cava, pulmonary arteries, pulmonary veins, and root of the aorta (The ascending aorta begins at the aortic valve, approximately at the level of the third costal cartilage, as the continuation of the left ventricular outflow tract, and is usually up to 2.1cm wide [6] [7], carrying newly oxygenated blood to the body. It ascends for about 5cm before becoming the aortic arch at the sternal angle, which continues superiorly, curving slightly to the left and posteriorly over the hilum of the left lung before descending again in the posterior mediastinum where, at the level of T4, it continues as the thoracic aorta.

The apex of the aortic arch is where its three branches are given off: the brachiocephalic trunk, the left common carotid artery, and, latterly, the left subclavian artery. Just anteriorly to these near vertical branches, the left superior intercostal vein is draped obliquely across the aortic arch. As it travels horizontally from posterolateral to anteromedial, it first crosses over the left vagus nerve, then under the left phrenic nerve, before draining into the left brachiocephalic vein.)

Question 12

List the main branches of the great vessels

Answer 12

see question below

Question 13

Describe the supply territory of the great vessels and their branches

Answer 13

Aorta

The aorta is the largest artery in the body. It carries oxygenated blood (pumped by the left side of the heart) to the rest of the body.

The aorta arises from the aortic orifice at the base of the left ventricle, with inflow via the aortic valve. Its first segment is known as the ascending aorta, which lies within the pericardium (covered by the visceral layer). From it branch the coronary arteries. The second continuous segment is the arch of the aorta, from which branch the major arteries to the head, neck and upper limbs. These are:

Brachiocephalic trunk
Left common carotid artery 
Left subclavian artery 

After the arch of the aorta, the aorta then becomes the descending aorta which continues down through the diaphragm into the abdomen.

The pulmonary arteries receive deoxygenated blood from the right ventricle and deliver it to the lungs for gas exchange to take place.

The arteries begin as the pulmonary trunk, a thick and short vessel, which is separated from the right ventricle by the pulmonary valve. The trunk is located anteriorly and medially to the right atrium, sharing a common layer of pericardium with the ascending aorta. It continues upwards, overlapping the root of the aorta and passing posteriorly.

At around the level of T5-T6, the pulmonary trunk splits into the right and left pulmonary arteries. The left pulmonary artery supplies blood to the left lung, bifurcating into two branches to supply each lobe of the lung. The right pulmonary artery is the thicker and longer artery of the two, supplying blood to the right lung. It also further divides into two branches.

Pulmonary Veins

The pulmonary veins receive oxygenated blood from the lungs, delivering it to the left side of the heart to be pumped back around the body.

There are four pulmonary veins, with one superior and one inferior for each of the lungs. They enter the pericardium to drain into the superior left atrium, on the posterior surface. The oblique pericardial sinus can be found within the pericardium, between the left and right veins.

The superior pulmonary veins return blood from the upper lobes of the lung, with the inferior veins returning blood from the lower lobes. The inferior left pulmonary vein is found at the hilum of the lung, while the right inferior pulmonary vein runs posteriorly to the superior vena cava and the right atrium.

Superior Vena Cava

The superior vena cava receives deoxygenated blood from the upper body (superior to the diaphragm, excluding the lungs and heart), delivering it to the right atrium.

It is formed by merging of the brachiocephalic veins, travelling inferiorly through the thoracic region until draining into the superior portion of the right atrium at the level of the 3rd rib.

As the superior vena cava makes its descent it is located in the right side of the superior mediastinum, before entering the middle mediastinum to lie beside the ascending aorta.
Inferior Vena Cava

The inferior vena cava receives deoxygenated blood from the lower body (all structures inferior to the diaphragm), delivering it back to the heart.

It is initially formed in the pelvis by the common iliac veins joining together. It travels through the abdomen, collecting blood from the hepatic, lumbar, gonadal, renal and phrenic veins. The inferior vena cava then passes through the diaphragm, entering the pericardium at the level of T8. It drains into the inferior portion of the right atrium.

Question 14

Define the boundaries of the mediastinum and the pleural cavities

Answer 14

thoracic aperture to diaphragm
sternum to verterbral column

plural cavities: Superior: root of the neck, 2-3 cm above the level of rib one. Inferior: The thoracic surface of the diaphragm inferiorly. Medial: The mediastinum medially.

Question 15

Describe the pleura

Answer 15

Consists of
- visceral pleura
- pleural cavity (and fluid)
- parietal pleura
- endothoracic fascia
- diaphragm

Question 16

Describe the pericardium

Answer 16

Consists of the following structures:
- visceral pericardium or epicardium
- pericardial cavity and fluid
- parietal pericardium
- fibrous pericardium
- central tendon of the diaphragm

Question 17

Describe the nerve supply of the thoracic cage

Answer 17

Somatic:
- - intercostal nerves (posterior, priperal 6, sensory; branches of c345 phrenic, cnetral)

Note on intercostals:
During their course, collateral, lateral cutaneous, and anterior cutaneous branches branch off. The anterior ramus branches innervate the skin over the ribs and muscles of the thoracic wall. The posterior ramus branches go on to innervate the skin over the posterior thoracic wall and the muscles of the spine.

i.e. contents:
-motor ohrenic nerves, phrenic 345 (pericardium, diaphramg, lung via hila)

Contents:
Autonomic:
sympatheically: trunk, t1-l2
parasymapttic: vagus, dorsal nucleus in medilla— enters via common carotids and int jugular veins, branches to plexuses in cardia, pulmo and oseo, out via eso hiatus in diaphragm

The left recurrent laryngeal nerve branches off the left vagus nerve at the level of the aortic arch.[17][22] It traverses medially, inferior to the aortic arch, and ascends to enter the neck. The right recurrent laryngeal nerve does not enter the thoracic cavity but traverses under the right subclavian artery from the right vagus nerve. Palsy of the recurrent laryngeal nerve affects the laryngeal muscles.[23]

The brachial plexus originates from C5 to T1 spinal nerves and is situated superior to the thorax.[19] As trunks, divisions, and cords form, nerves branch off to supply muscles superficial to the thoracic wall; this includes the dorsal scapular, medial and lateral pectoral, long thoracic, and thoracodorsal nerves.

Question 18

List the layers of the thoracic wall

Answer 18

Skin
Superficicla fascia and fat
muscle e.g. serratus anterior
rib
external intercostal
internal intercostal
– intercostal artery vein and nerve, and collatral branches
inner most
endothoraic fascia
partierl pleura
(pericardium– fibrous, serous partieal and viscaeral)
pleural cavity
visceral
lung

Question 19

Describe the pulmonary and systemic circulation

Answer 19

The pulmonary system connects the heart and the lungs and its primary function is gas exchange. The pulmonary trunk arise from the right ventricle and carry de-oxygenated blood to the lungs trough the left and right pulmonary arteries. Following gas exchange at the pulmonary alveoli, pulmonary veins return to the left atrium of the heart to deliver oxygenated blood.

The primary role of the systemic arterial system is to deliver oxygenated blood to all regions of the body to supply bones, muscles, viscera. The aorta arises from the left ventricle of the heart and produces a number of branches that deliver blood to target regions in the body. De-oxygenated blood returns to the right atrium of the heart via 3 veins: superior vena cava, inferior vena cava drain blood from the body, while the coronary sinus drains blood from the heart tissue directly.

Artery - from the Greek word aeirein=to raise, typically describe blood vessels that move blood away from the heart.

Vein - from the Latin word venā=blood vessel. To come in Latin is coming is veni, the vessels that deliver blood towards the heart are nominated as veins.

Please note, that this anatomical distinction is always true for every vessel, however, categorisation by blood content is not. In the systemic circulation arteries carry oxygenated blood to the body, while veins carry de-oxygenated blood back to the heart. In the pulmonary system arteries deliver de-oxygenated blood to the lungs for gas exchange and pulmonary veins return oxygen-rich blood to the heart.

Question 20

List the valves of the heart

Answer 20

The location of the valves is easy to remember using the mnemonic All Patients Trust Me (APTM). As one looks at the heart, starting from the left, the first valve to be found is the Aortic, followed by the Pulmonary, followed by the Tricuspid/right AV/, followed by the Mitral/left AV (APTM).

The easy way to remember the bicuspid/tricuspid order is to remember that you ride a tricycle before you ride a bicycle. The tricuspid always comes first. It’s on the right side and separates the right atrium from the right ventricle. The bicuspid separates the left atrium from the left ventricle.

Semi-lunar valves:
Aorta:The aortic valve normally has three cusps however there is some discrepancy in their naming.[2] They may be called the left coronary, right coronary and non-coronary cusp– small proportion of population are biscusp
Pulmonary: tricusp

Question 21

Describe the location of the thymus

Answer 21

Superior mediastinum
NB atrophies with age

Question 22

List the key types of blood vessels and how their structure is related to function

Answer 22

Artery - from the Greek word aeirein=to raise, typically describe blood vessels that move blood away from the heart.

Vein - from the Latin word venā=blood vessel. To come in Latin is coming is veni, the vessels that deliver blood towards the heart are nominated as veins.

Please note, that this anatomical distinction is always true for every vessel, however, categorisation by blood content is not. In the systemic circulation arteries carry oxygenated blood to the body, while veins carry de-oxygenated blood back to the heart. In the pulmonary system arteries deliver de-oxygenated blood to the lungs for gas exchange and pulmonary veins return oxygen-rich blood to the heart.

tructure of vessel walls

Despite varying sizes and functions, most blood vessels share a similar structure being composed of three layers or “tunics”: from the lumen to the outside, these are the endothelium (a thin layer of endothelial cells), which sits on a basal lamina, the sub-endothelial connective tissue, and an internal elastic membrane.

Tunica intima – the innermost layer. Consists, from lumen out, of the endothelium (a thin layer of endothelial cells), which sits on a basal lamina, subendothelial connective tissue, and an internal elastic membrane.
Tunica media – the middle layer. Consists of multiple layers of smooth muscle cells arranged circumferentially, and contains varying amounts of elastic tissue.
Tunica adventitia – the outermost layer. Consists of connective tissue. Varies in thickness, and in collagen and elastin content.

Elastic (conducting) arteries

Elastic arteries include the aorta, pulmonary, common carotid, brachiocephalic, subclavian, and iliac arteries.

The tunica media is the thickest layer, consisting predominantly of sheets of elastic tissue separated by thin layers of collagen fibers and smooth muscle cells.

These vessels are too thick to obtain oxygen and nutrients from their lumen by diffusion – instead they have their own small arteries (called the vasa vasorum) present in the tunica adventitia.

Muscular (distributing) arteries

Muscular arteries arise from the elastic arteries and are the most abundant type of artery in the body.

They are characterized by a thick tunica media comprised of concentric layers of smooth muscle cells. The tunica media is bordered by the internal elastic lamina and external elastic lamina. These muscular and elastic components allow the arteries to contract and relax to regulate tissue blood supply.

Small arteries and arterioles (resistance arteries)

Arterioles are distinguished from small arteries by a lumen with a diameter smaller than 300 μm.

The tunica intima is very thin – comprised of endothelium, connective tissue and a thin internal elastic lamina.
The tunica media contains < 6 concentric layers of smooth muscle cells – this enables arterioles to control blood flow to the capillaries.
The tunica adventitia consists of elastin and collagen fibers arranged longitudinally and circumferentially.

Sympathetic nervous system and local changes in the tissue environment regulate their constriction and dilation thereby controlling the blood flow in an area (‘demand and supply’ principle)

Capillaries (exchange vessels)

Capillaries form extensive networks within tissues. There are several types of capillaries, but they all share similar characteristics:

The tunica intima consists of a single layer of endothelial cells.
The tunica media is missing and the tunica adventitia is greatly reduced or absent.

Gases, fluids and molecules are exchanged through their walls, to exchange between tissue and blood.

Three types of capillaries provide different rate of permeability. The majority of capillaries are continuous. Fenestrated capillary walls allow movement of larger molecules across the wall. They are found in the small intestine, to allow nutrient absorption, kidneys, choroid plexus and endocrine organs for blood filtration. Sinusoids are the rarest. The large gaps in the basement membrane and the endothelium allow movement of large molecules and even cells across the wall. They are found in the liver, spleen, bone marrow and lymph nodes.

Venules

Venules connect the capillary bed with veins, and share many structural characteristics with veins:

The tunica intima is very thin – comprised of endothelium, connective tissue and a thin internal elastic lamina.
The tunica media is poorly developed.
The tunica adventitia consists of fibrous connective tissue.

	Medium veins

Medium veins are those with a diameter of
1–10 mm.

The tunica intima and tunica media are thinner than in similarly-sized arteries:

The tunica intima comprises a thin layer of endothelial cells.
The tunica media consists of 2 or more layers of circularly arranged smooth muscle. Because of the low luminal pressure, this is sufficient to produce appreciable changes in the radius of the veins and hence in the volume of blood held within them.
The tunica adventitia is the predominant layer, consisting of collagen and elastin fibers, and longitudinally arranged smooth muscle fibers.

Due to the thinner, less resistant vessel wall, veins are distensible and serve as blood reservoirs (~70% of blood is held in veins and venules).

Large muscular veins

Large veins include the vena cavae, splenic, portal, renal, external iliac and mesenteric veins.

The tunica intima comprises a thin layer of endothelial cells.
The tunica media is poorly developed, consisting of smooth muscle with some elastic and collagen fibers.
The tunica adventitia is the broadest layer, comprising bundles of collagen, elastin and smooth muscle fibers. In some veins (such as the vena cavae), the smooth muscle bundles are longitudinally arranged.

The tunica adventitia may also contain vasa vasorum.

all blod vessels have elastin exc caps

Question 23

Which of the following statement regarding the thoracic wall is FALSE?

The intercostal vein, artery and nerve run in the costal groove between the the external and internal intercostal muscles

The posterior intercostal veins drain into the azygos vein on the right, and the hemiazygos on the left side

The anterior intercostal artery is a branch of the internal thoracic artery

The internal and innermost intercostal muscle are activated during forced/active expiration

Neck muscles attached to ribs are utilised during forced inspiration

Answer 23

The intercostal vein, artery and nerve run in the costal groove between the the external and internal intercostal muscles

THIS IS FALSE

Correct, this statement is false, as the intercostal neurovascular structures run in the costal groove that is bodered by the internal and innermost intercostal muscles

Question 24

Structures that normally cross the diaphragm through the esophageal hiatus include the…

Answer 24

Posterior vagal trunk

The vagus nerve or cranial nerve X, that is responsible for the innervation of the thoracic, and the majority of abdominal viscera, crosses the diaphragm with the esophagus

Question 25

Which of the following structures does NOT MOVE with the second rib during respiration?

body of sternum, second thoracic vertebral body, third thoracic verterbral body, transverse process of T2, manubrium of sternum,

Answer 25

Third thoracic vertebral body

body and manubrium of sternum, second thoracic vertebral body, transverse process of T2 do move.
IE rib 2 connects to T1 and T2, not T3

Question 26

Which statement regarding the lungs is correct?
- left lung has two lobes and is separated by the horizontal fissure
- oxygenated blood to the lungs is provided principally by the pulmonary circulation
- pulmonary and bronchial vessels are both present at hilum
- only left lung has cardiac impression, because the apex of the heart is directed to the left
- apex of the lungs are covered by the diaphragmatic pleura

Answer 26

C

The pulmonary vessels enter and exit the lung through the hilum, to carry blood between the heart and lungs for gas exchange. Bronchial arteries are branches of the aorta, and enter the lung to supply lung and bronchial tissues, bronchial veins drain the tissue to the azygos and hemiazygos veins

Question 27

Which statement, regarding the heart is correct?
- the pericardial cavity is in between fibrous and serous pericardium
- heart activity is controlled by the ANS
- pectinate muscles are found in both the atrium and the ventricle
- the trabeculae attach to papillary muscles and control the opening and closing of the atrioventricular valves
- the two pairs of pulmonary arteries carry oxygen-rich blood to the atrium

• pericardial cavity (sim to pleural cavity) lies between layers of serous pericardium

Answer 27

A

Question 28

Which of the following statement is INCORRECT, regarding the mediastinum?
- heart and the root of great vessels are found in the middle mediastinum
- aortic arch is found in superior mediastinum
- branches of the internal thoracic artery are found in the anterior mediastinum
- the thoracic aorta is found in the middle mediastinum
- the azygos and hemiazygos veins are found in posterior mediastinum

Answer 28

D

The internal thoracic arteries descend on the lateral edge of the sternum, partially embedded in the retrosternal fatty layer of the anterior mediastinum

Question 29

Fill in the blanks:
The heart is located in the - between the -. - to the superior edge of the sternum, anterior to the - and - to the diaphragm. The heart is inside the - , a closed sac 1-2 mm thick. This sac has two layers, the outermost of which is the - . This layer is anchored superiorly to the large -, where they attach to the base of the heart, and inferiorily to the - . The second, inner layer of the sac is the - , which is a double-layered membrane. The – layer is attached to the fibrous pericardium, while the – layer is attached to the heart itself. The potential space between the two layers is called the – which contains a lubricant called —, that allows the layers to slide over each other smoothly as the heart beats.

Answer 29

mediastinum, middle mediastinum, between the anterior mediastinum, posterior to the superior edge of the sternum, anterior to posterior mediastinum
and superior to diaphragm.

Sac has two layers, fibrous pericardium, tough texteranl laer, atached to base of heart, and inferioryl to central, tendon, with which it is continuous

The second, double layerparitel serous pericardoumm, attached to fibrous, visceral, relfection, attached to heart and great vessels

potential space is percairdial caivity, lubricant called, pericardial (serous) fluid

Side notes on middle mediastinum:
subdivision ofinfereior mediastinum that spans transverse thoracic plane and diaohragm, T9 to T12

middle: pericardium and content:
pericardiu is fibroserousmembrane, sourrounds heart and root so f greta vessel, entry of vena cava, aorta,
- fibrous pericardium
-partietal and visceral

note: apex: continuous with advvneitia of great vesel
basE: diaphragm, fibrous pericardium contunous

Question 30

The heart has three layers, the outermost of which is the — (this layer is also called the visceral layer of the serous pericardium). The inner layer, or —, is only a few cells thick and is the only layer to come into direct contact with blood. The middle layer, called the — is the thickest of the three. Its muscle fibres are bound together by the —, a dense connective tissue, whih separeates the —, the receiving chambers of the heart, from the —, the pumping chambers of the heart.

Answer 30

1. parietal?
2. serous
3. fibrous
4. fibrous skeleton
5. atria
6. ventricles

Question 31

Identify the borders of the thoracic cavity

Answer 31

• RIBS
• Intercostal ms
• intercostal artery, vein, nerve in intercostal space
• azygos and hemiazygos veins
• internal thoracic artery and vein
• ventral rami of spinal nerve
• diaphragm
• phrenic nerves

Question 32

List the contents of the thoracic cavity: pleural and mediastinum

Answer 32

• heart
• lungs
• vagus nerves
• aorta: ascending, arch and descending
• vena cava: superior and inferior
• pulmonary trunk and arteries
• pulmonary veins
• oesophages
• trachea

Question 33

Describe the pleura and pericardium and their relationships

Answer 33

The pericardium is a fibrous sac that encloses the heart and great vessels. It keeps the heart in a stable location in the mediastinum, facilitates its movements, and separates it from the lungs and other mediastinal structures. It also supports physiological cardiac function

The pericardium consists of two layers: the fibrous and the serous. The fibrous pericardium is a conical-shaped sac. Its apex is fused with the roots of the great vessels at the base of the heart. Its broad base overlies the central fibrous area of the diaphragm with which it is fused.

The serous pericardium is a layer of serosa that lines the fibrous pericardium (parietal layer), which is reflected around the roots of the great vessels to cover the entire surface of the heart (visceral layer). Between the parietal and visceral layers is a potential space that may be filled with a small amount of fluid. The part of the visceral layer that covers the heart, but not the great vessels is called the epicardium.

As the serous pericardium reflects off various cardiac structures, it forms two sinuses: the transverse sinus and the oblique sinus. The oblique sinus is a cul-de-sac extending superiorly from the inferior vena cava between the two left pulmonary veins on one side and the two right pulmonary veins on the other. Its anterior wall is formed by the posterior wall of the left atrium, between the four pulmonary veins. The oblique sinus provides expansion space for the left atrium. The transverse sinus is open at both ends and formed by the reflection of visceral serosal pericardium from the posterior aspects of the aortic and pulmonary trunks over to the anterior aspect of the atrium. Thus, a finger in the transverse sinus will pass behind the aortic and pulmonary trunks, in front of the superior vena cava on the right, and the left atrial appendage on the left.

pericardium surrounded by reflection of parieral pluera known as mediastinal pleura

Question 34

List the great vessels

Answer 34

Superior vena cava
Inferior vena cava
Pulmonary trunk
Left and right pulmonary arteries
Pulmonary veins
Aorta: ascending, arch, descending
Brachiocephalic trunk, left common
carotid, left subclavian

essentially everything you can think of, primary branches, and not the azygoses

Question 35

List the corobary vessels

Answer 35

R and L coronary artery, coronary sinus

Question 36

List the key features of the lungs

Answer 36

Root: bronchi, pulmonary artery, pulmonary veins, bronchial vessels, nerves, lymphatics
pulmonary trunk
Hilum
Left and right pulmonary arteries
Left and right pulmonary veins
Aorta: ascending , arch, descending

Question 37

Distinguish between hilum and root of the lung

Answer 37

The root of the lung is the collection of structures that connect the lung to the mediastinum. This includes the pulmonary arteries and veins, the primary bronchi and bronchial arteries, and the pulmonary nerve plexuses and lymphatics. The hilum is the place on the lung where these structures enter and leave the lung.

the hilum aids the lung roots by anchoring the lungs to the heart, trachea, and surrounding structures.

note copied

Question 38

Describe the properties of blood vessel walls

Answer 38

Structure of vessel walls

Despite varying sizes and functions, most blood vessels share a similar structure being composed of three layers or “tunics”: from the lumen to the outside, these are the endothelium (a thin layer of endothelial cells), which sits on a basal lamina, the sub-endothelial connective tissue, and an internal elastic membrane.

Tunica intima – the innermost layer. Consists, from lumen out, of the endothelium (a thin layer of endothelial cells), which sits on a basal lamina, subendothelial connective tissue, and an internal elastic membrane.
Tunica media – the middle layer. Consists of multiple layers of smooth muscle cells arranged circumferentially, and contains varying amounts of elastic tissue.
Tunica adventitia – the outermost layer. Consists of connective tissue. Varies in thickness, and in collagen and elastin content.

Question 39

Is common carotid an elastic or muscular artery?

Answer 39

Elastic

Question 40

Is brachiocephalic trunk an elastic or muscular artery?

Answer 40

Elastic

Question 41

Define end arteries

Answer 41

End arteries are single branches responsible to supply a particular territory without the support of neighbouring arteries. Consequently, their occlusion causes ischaemia that leads to tissue infarction.

Question 42

Define anastomoses

Answer 42

Direct connection between two vessels described as anastomosis.

Question 43

Distinguish between true and potential anastomoses

Answer 43

Direct connection between two vessels described as anastomosis. Areas with large number of branches have more potential for anastomoses between neighbouring branches . These collateral circulation can serve as a ‘back up system’ in case of vascular blockage, thus allow protection of important structures, such as the brain. True anastomoses are formed between larger muscular arteries connected end-to-end creating arcades that continuously communicate (e.g. palmar and plantar arches, intestinal arcades, circle of Willis).

Potential anastomoses are formed between arterioles. They are much smaller in caliber but they have the capacity to dilate, when a slow, gradual occlusion occurs in one branch. Collateral vessels can deliver oxygen to the supply area.

Question 43

Describe venous flow and venous return

Answer 43

Venous flow: gracity affects return.

• valves, prevent backflow,
• nervous inneration–smooth muscle contraction, constrict vessel, decrese vol increase pressure to return to heart
• skel muscle, squeeze, pump with valeces back
• respiratory movment pump– lower thoracic inc abdo, up
• suction of herat: pressure decrease in ritht atrium, vacuum

Venous blood pressure is very low and the pressure of the blood filling the right atrium is lower still. This means that the filling of the right atrium is an entirely passive process. It is also a crucial process because the amount of blood entering the right atrium directly determines the amount of blood leaving the heart (the cardiac output). For this reason, we can say that a very important factor determining cardiac output is venous return.

Question 44

Describe the pectoral girdle movements

Answer 44

The shoulder girdle, also called the pectoral girdle, is an incomplete bony ring formed by the clavicle and scapula on each side of the body, joined anteriorly by the manubrium of the sternum. The bones of the shoulder girdle articulate with each other and partake in the formation of 4 joints that include:

The sternoclavicular joint - formed between the sternum and clavicle.
The acromioclavicular (AC) joint - formed between the scapula and the clavicle.
The glenohumeral (shoulder) joint - formed between the scapula and humerus.
The scapulothoracic joint - formed between the scapula and the posterior thoracic cage. (physiological)

Anchr- attaches upper limbs to axial skeleton, large range of motion (st)

SC:
- saddle joint by shape
- fucntionally ball and skeleton
- anterior and posterior movemtn
- elevation and depresssion
- circumduction, pivot for acromial circular motion

AC:
- plane
- ligaments many , corcacoid of scapula

Glenohumeral:
- ball and socket
- many ligaments (glenouhumeral)
- rorator cuff (four msucles)

ST:
- ant surface of scapula and posterior thoracic joint- permits most of motion, the sternoclav

The movements of the scapula are translated to the shoulder girdle as follows:

Protraction of the scapula: By moving the scapula laterally away from the spine, the shoulders are moved anteriorly and inwards.
Retraction of scapula: This movement pulls the scapula medially towards the spine and moves the shoulders backwards and inwards.
Elevation of scapula: Movement that allows the shoulder girdle to move upwards as in shrugging the shoulders.
Depression of scapula: In contrast to the latter, this movement allows for the scapula and shoulder girdle to move downwards.
Upward rotation of scapula: By rotating the lower scapula laterally and upwards the shoulder girdle moves upwards and inwards.
Downward rotation of scapula: Movement that rotates the lower scapula towards the spinal column that moves the shoulder girdle downwards.

Question 45

Describe the muscle movements when breathing

Answer 45

• inspiration: diaphagm, contracts, expands pleuarl cavity longitidianlly, descends, helps elevate lower ribs (transversre)
• ext elevate
• parastiernal inercarilagoinsous

acces: stero and scalen: elevate strenim; elevate dand fix upper ribs

exp: passive, recoil of lungs
active: internal intercostal (not para) to depress ribs
abdo (depress lowe liubs, decrease cavity, compress contents)

Question 46

Which muscles are primary in inspiration?

Answer 46

Diaphragm
ext intercostals

all else accessory

Question 47

List parts of partietal pleura

Answer 47

The parietal pleura actually has four parts: costal, mediastinal, diaphragmatic and cervical pleura.

Question 48

Describe azygos veins and hemiazygos veins

Answer 48

The azygos venous system is located on either side of the vertebral column and drains the viscera within the mediastinum, as well as the back and thoracoabdominal walls. This system consists of the azygos vein and its two main tributaries: the hemiazygos vein and the accessory hemiazygos vein.

The azygos vein usually arises either from the lumbar azygos vein or from the posterior side of inferior vena cava

It passes through the diaphragm, reaches the mediastinum and finally drains into the superior vena cava. The azygos venous system has many anastomoses with inferior vena cava and vertebral venous plexuses. This makes it an important connection between the two venae cavae

note: not a great vessel

starts from IVC end s in SVC