WEEK 4 Flashcards

Question

What does the (i) Anterior Ipsilateral Corticospinal Tract (ii) Lateral Contralateral Corticospinal Tract, provide?

Answer 1

(i) postural compensation for movements contralaterally | (ii) fine voluntary control over distal muscles

Answer 2

Are quite common as axons are very long (UMNs) Signs of lesions are presented as +ve or -ve signs -ve = loss of function +ve = appearance of an abnormal response Ex. of a +ve response is the Babinski sign (toes fanning). - these lesions give rise to UMN syndrome LMN lesions: cause muscle paralysis, reduced muscle tone, reduced stretch reflex, fasciculation, atrophy NOTE: in UMN lesions, there's no atrophy or fasciculation but muscle tone increase often leads to painful spasticity

Answer 3

[D] + [R] [DR] k1 = rate constant for associations k2 = rate for dissociations rate associations = k1.[D].[R] rate dissociations = k2.[DR]

Answer 4

The equilibrium dissociation constant - when the rate of associations = rate of dissociations It represents the concentration of a drug required to occupy 50% of receptors at equilibrium It is 1. different for every drug 2. A measure of the affinity of one drug for a receptor

Answer 5

pD2 = -log10(K(D)) | the greater the pD2 value, the greater the drugs affinity

Answer 6

[D] + [R] [DR] [DR]* note [DR]* = active alpha pathway (backwards) = rate constant of receptor inactivation beta (forward) pathway = rate constant of receptor activation

Answer 7

If less than 100% of the receptors are required to evoke a maximum response, then the "extra`' receptors are referred to as spare receptors

Answer 8

Very efficacous drugs require to occupy fewer receptors to give a response than less efficacous ones

Answer 9

They decrease the response to a full agonist as some receptors will be occupied by partial agonists - giving a smaller response than if all the receptors were occupied by full agonists

Answer 10

A competitive antagonist is a drug which interacts/binds reversibly with receptors to form a complex but this complex does NOT evoke a response

Answer 11

It displaces it to the right | - however, the max response to the agonist remains the same

Answer 12

The equilibrium dissociation constant for an antagonist, - The concentration of an antagonist that means you have to add twice as much agonist to produce the same response that would be achieved if no antagonist was present

Answer 13

pA2 = -log10 (K(A))

Answer 14

Binds to the receptor, but dissociates very slowly - if at all! This results in the slope of the Log dose-response curve being decreased AND the max response being decreased

Answer 15

They can modify the affinity OR efficacy of a receptors endogenous ligand or drug.

Answer 16

1. AFFINITY = concentration range over which a drug binds to its receptor 2. EFFICACY = ability of drug to generate/initiate a stimulus once bound to its receptor.

Answer 17

1. ENDOTHELIAL INJURY - formation of thrombi in heart & arteries 2. ALTERATIONS IN NORMAL BLOOD FLOW - tubulence = cardiac & arterial thrombi - stasis = venous thrombi 3. HYPERCOAGUBILITY (alteration of blood coagulation which predisposes thrombosis) - primary (genetic) = mutation in factor V gene, AFIII deficiency, protein C&S deficiency - secondary (acquired) = high risk (bed rest, MI, tissue damage) low risk (myopathy, AF, oral contraceptive, sickle cell anaemia, smoking)

Answer 18

after vessel injury, platelets undergo 3 important reactions: 1. adhesion 2. secretion 3. aggregation

Answer 19

1. mural thrombi: - one wall of underlying structure - capacious lumina of heart chambers and aorta 2. arterial thrombi - usually occlusive - can be mural - frequent in: coronary, cerebral, femoral - grey, white and friable 3. venous thrombi (phlebothrombosis) - occlusive & dark red - veins of the lower extremities (90%)

Answer 20

1. Arterial - loss of pulses distal to thrombosis - areas become: pale perishing cold, painful, paraesthesia - eventually results in tissue death & gangrene 2. Venous - superficial: congestion, swelling pain, tenderness - deep: foot & ankle oedema, asymptomatic (recognise only once embolised)

Answer 21

Stockings is used as a prevention mechanism | Anticoagulant drugs are used to prevent clot growth

Answer 22

1. Pulmonary embolism - arise from DVT (95%) clinical course = result in respiratory & haemodynamic compromise 2. Systemic embolism - through arterial system - 80-85% come from within heart - almost always = infarction major sites = lower extremities, brain, viscera, UL. 3. Air Embolism - bubbles of air/gas within circulation obstruct vascular flow and damage tissues = BAROTRAUMA arise from: pneumothorax, caissons disease, delivery/abortion, lung/chest wall injury 4. Fat Embolism - due to fractures of long bone shafts or soft tissue trauma/burns - characterised by: pulmonary insufficiency, neurologic symptoms, anaemia & thrombocytopenia - symptoms after latent 24-72 hrs sudden onset of: trachypnoea, dyspnoea, tachycardia, irritability & restless -> deriulium & coma 5. Amniotic Fluid Embolism: - labour complication = maternal mortality (86%) - infusion of amniotic fluid into maternal circulation - clinical presentation = respiratory difficultly (deep cyanosis & CV shock) -> convulsions -> coma

Answer 23

``` Thrombosis & embolism Vasospasm Atheroma expansion Twisting of vessels Traumatic rupture ```

Answer 24

``` Red (haemorrhagic) - venous occlusions - in loose tissues - tissues w. dual circulation White (anaemic) - arterial occlusions - solid organs Septic or Bland ```

Answer 25

Haemorrhagic: - ovarian = venous, dark blue & haemorrhage - lung = loose tissue, wedge shaped, red & haemorrhagic - SI = dual circulation, red & haemorrhagic Anaemic - spleen = wedge shaped, white - kidney = wedge shaped, white

Answer 26

- single vascular supply vs dual - rate of occlusion development - vulnerability to hypoxia - lack O2 content in blood = faster infarction (anaemic/cyanotic)

Answer 27

Pre ganglionic fibres originate from the CNS | Post ganglionic fibres originate from the autonomic ganglia

Answer 28

1. Pupillary dilator muscle - sympathetic innervation - mydriasis 2. Pupillary constrictor muscle - parasympathetic innervation - miosis

Answer 29

- pre ganglionic fibres synapse on chromaffin cells and release adrenaline (80%) and noradrenaline (20%) into the systemic circulation => eliciting a widespread tissue response

Answer 30

``` Parasympathetic: - pre = NACh - post = MACh Sympathetic: - pre = NACh - post = NA (note: some release ACh i.e. sweat glands) ```

Answer 31

MUSCULOCUTANEOUS (C5, 6, 7): motor to flexors of the arm (BBC) & sensory as the lateral cutaneous nerve of the FA AXILLARY (C5, 6): motor to the deltoid & teres minor & sensory to the skin over the lower part of the deltoid (as the superior lateral brachial cutaneous nerve) RADIAL (C5-T1): motor to extensor muscles of the arm & FA & sensory to posterior skin of arm, FA & hand.

Answer 32

AXILLARY: passes posteriorly through the quadrangular space & lies on the surgical neck of the humerus with the posterior circumflex humeral artery MUSCULOCUTANEOUS: pierces coracobrachialis & eventually becomes the lateral cutaneous nerve of the forearm (C6,7) where it terminates by exiting lateral to the biceps running with the cephalic vein near the cubital fossa. Then descends the lateral FA anteriorly to the wrist RADIAL: passes posteriorly through the lower triangular space with profunda brachii artery. Passes posterior to humerus & descends arm in the radial groove between the lat & med heads of triceps. Enters cubital fossa by piercing lat inter-muscular septum. Divides into a superficial cutaneous branch & a deep motor branch once in the FA

Answer 33

``` SUPERIOR GLUTEAL (L4, L5, S1) INFERIOR GLUTEAL NERVE (L5, S1, S2) SCIATIC (L4, L5, S1, S2, S3) COMMMON FIBULAR (L4, L5, S1, S2) SUPERFICIAL FIBUALR (L5, S1, S2) DEEP FIBULAR (L4, L5) FEMORAL (L2, L3, L4) ```

Answer 34

SUP GLUT: enetrs sciatic foramen above piriformis & runs laetrally between gluteus med & min & splits into a sup branch (glut med) & an inf branch (glut min & tensor fasciae latae) INF GLUT: enters sciatic foramen below piriformis & runs deep to glut max - innervating it SCIATIC: enters gluteal region via greater sciatic foramen & runs below piriformis & deep to glut maximus, midway between the ischial tuberosity & greater trochanter, behind hip joint. Terminates as tibial & common fib at apex of pop fossa. Innervates muscles in posterior thigh, all muscles in leg & foot & articular branches to all LL joints. COMMON FIB: Runs inferiorly & laterally following medial border of the biceps, passing over the lat head of gastroc & winding round neck of fibula where is terminates as superficial fib (lat compartment) & deep fib (ant compartment). Innervates lateral aspect of the knee joint FEMORAL: descends in abdomen then travelling through the pelvis to midpoint of inguinal lig. Then traverses behind the inguinal lig into thigh. Passes through femoral triangle & gives off articular branches to hip and knee joints. Terminal cutaneous branch of the femoral nerve=saphenous nerve which continues(with the femoral artery and vein) through the adductor canal to the leg. Innervates muscles of ant thigh

Answer 35

Injury to superior = compromised hip joint with interrupted medial rotation & abduction of the thigh. Would transfer to the centre of gravity over the supporting lower limb 'glut medius limp' When glut medius & minimus are affected, pt has Trendelenburg gait. Compensated for by producing waddling gait (raising pelvis to allow clearance of the foot moving forward) Can also arise from dislocation of the hip or fracture of the greater trochanter.

Answer 36

Injury results in reduced abduction (beyond 15 degrees) & muscular atrophy (flattened shoulder) Injuries can occur upon fracture of the surgical neck or dislocation of the GH joint Injury will also affect sensation over the lateral proximal arm area near the inferior deltoid because of loss of innervation through the superior lateral cutaneous nerve of the arm

Answer 37

Injury would result in paralysis of the BBC muscles causing weak flexion of the shoulder & GH joint, elbow joint & weak supination Would also cause loss of sensation to the lateral FA

Answer 38

Median nerve Brachial artery Biceps tendon Radial Nerve

Answer 39

Injury commonly presents as 'wrist drop'. Wrist partly flexed due to the flexor muscles still being intact. Extension of wrist & fingers at MCP joints compromised. Injury in post. FA: extension of thumb & MP joint compromised Testing for radial nerve integrity = ask pt to extend MP joints against resistance (if intact long extensor tendons will show)

Answer 40

Compression of the nerve can occur due to its trajectory under the piriformis muscle (including muscle spasms). Is more common in athletes & woman Direct injury/trauma would eliminate extension of hip & thigh & flexion of leg.

Answer 41

Susceptible to injury in dislocation of knee joint or upon fibular fracture. Severe injury of nerve paralyse muscles in lat & ant compartments of leg => foot drop (loss of dorsiflexion of ankle & foot evertors). Toes don't clear the ground during walking, requiring compensation, but resulting in foot slaps Loss of sensation can occur in anterolateral aspect of leg & dorsum of foot

Answer 42

1. Direct contact with infected blood fluids 2. Infection via contaminated needles, syringes, or other unsterilised instruments 3. Direct infection into the bloodstream by arthropod vectors (e.g. mosquitoes)

Answer 43

1. Via blood/blood products ro contaminated needles 2. Sexually (virus is present in semen & vaginal secretions) 3. Perinatally (transplacentally during delivery, ingestion of breast milk)

Answer 44

Nucleoside reverse transcriptase inhibitors (NRTIs) Non- nucleoside reverse transcriptase inhibitors (NNRTIs) Protease inhibitors (PIs)

Answer 45

ELISA Western Blotting NAAT used to detect viral RNA in serum NOTE that an initial neg test should always be followed up

Answer 46

Blood or blood products Contaminated needles & equipment used by IV drug users Association with tattooing, body piercing & acupuncture

Answer 47

``` HBsAg = surface antigen - indicates infectivity - Anti-HBsAg provides immunity & appears late HBcAg = core antigen - appears early in infection HBeAg = pre core antigen - indicates high tansmissibility ```

Answer 48

``` Pre-icteric(jaundice) stage: - malaise - anorexia - nausea - pain in R upper quadrant (tender liver) Icteric stage - jaundice - Bilirubin (dark urine) ```

Answer 49

``` Pegylated interferon (peginterferon) is superior compared to alpha-interferon in sustaining suppression of viral replication - antiviral activity of nucleoside analogues may be successful even in chronic HBV pts ```

Answer 50

``` Flavivirus Single stranded RNA genome Enveloped Replicates primarily in hepatocytes Destroys liver cells Virus can't be cultured ```

Answer 51

Blood & blood products Tattooing, body piercing & acupuncture Haemodialysis

Answer 52

``` Usually asymptomatic Fatigue Nausea Weight loss May rarely progress to cirrhosis Small proportion may develop hepatocellular carcinoma ```

Answer 53

None that is specific Interferon reduces liver transaminases in 80% of pts Ribavirin works well in combo with pegylated alpha inferferon Monitor viral load by NAAT No vaccine yet available

Answer 54

Caused by 5 species of the genus Plasmodium - P.falciparum - P.vivax P.ovale P.malariae P.Knowlesi Female Anopheles mosquito injects sporozoa into the bloodstream (zoonotic disease)

Answer 55

Fever Flu-like symptoms P. falciparum infection can rapidly progress to death. It affects ever organ and has a wide range of complications - e.g. cerebral malaria, circulatory shock, hepatitis

Answer 56

At least 3 blood films (both thick and thin, thin identifies species whilst thick tells you how much is there) obtained from different times for microscopy NAAT = useful for detecting drug resistance

Answer 57

Chemo kills the blood stages of the parasite Resistance means treatment advice should be changed regularly Combination therapy is the norm: - Quinine, Chloroquine(issues w.resistance, Doxycycline, Proguanil, Malarone, Artemether

Answer 58

``` Sleep under bed nets Cover exposed skin between dusk & dawn Use of mosquito repellants Prophylaxis Vaccines currently being developed ```

Answer 59

C6, C7, C8, T1 Supplies muscles of anterior compartment of forearm except FCU and half of FDP (that to the ring & little finger) Anterior to brachialis & lower humerus in cubital fossa, posterior to bicipital aponeurosis, medial to brachial artery & biceps tendon Passes between 2 heads of PT to lie in the plane between FDS & FDP Reappears at the wrist lateral to the tendons of FDS, between them and FCR Before entering the carpal tunnel it gives (Superficial) Palmar Cutaneous Branch that passes superficial to the Flexor Retinaculum to supply the skin of the central palm

Answer 60

Injury common at cubital fossa by elbow dislocation, or by supracondylar fractures of humerus Flexion of thumb & index & middle fingers lost & these digits can't be made into a fist (pronation lost & ulnar deviation on wrist flexion) Injury to ant IO nerve causes loss of flexion of distal IP joints of thumb & index finger, the "OK" sign cannot be made

Answer 61

May affect median nerve progressively to cause tingling over the Thenar eminence & radial 3.5 digits The central palm is spared due to the more proximal origin of the palmar cutaneous branch Eventually there may be sensory loss with weakness & wasting of the thenar muscles

Answer 62

C7, C8, T1 Passes immediately post to med epicondyle of humerus Passes between 2 heads of FCU, to pass distally in FA between FCU & FDP At wrist, comes superficial, lying just medial to the ulnar artery & passes through the Ulnar (Guyon's) Canal, then anterior to flexor retinaculum to enter the palm

Answer 63

Common at medial epicondyle of humerus, causes senosry loss of both palmar & dorsal surfaces, of the medial hand & of the medial 1.5 digits. Loss of FCU causes difficulty in adduction of wrist & there is radial deviation upon wrist flexion Loss of FDP to ring & pinky fingers means their distal IP joint cant be flexed & flexion is now weakened in those medial fingers - now difficult for them to make a fist AT WRIST: loss of adductor pollicis (& deep head of FPB) Test: clasp sheet of paper between thumb & palm. Pt will use thumb abduction & flex of distal IP joints (giving a +ve Froment's sign). Also test the IO ULNAR CLAW:MCP extension, IP flexion => hand looks like a claw BUT the radial 2 lumbricals are still acting (median) so the claw is restricted to the ring & little fingers. (NOTE: the claw is less pronounced if the injury is at elbow as flexing affect of FDP is lost = ulnar paradox)

Answer 64

L4 - S3 Deep to biceps tendon, crosses fibular head & then around its neck, where it divides, deep to fibularis longus. Then divides into: SUPERFICIAL FIB: started between fibularis longus & brevis, but now subcutaneous & on its way to skin of lower, lateral leg & dorsum of foot (except 1st cleft) DEEP FIBULAR: passing through EDL to lie on the IO membrane, supplied all 3 muscles of ant compartment & descends towards ankle. Passes anterior to the tibia into dorsum of foot to supply ED & HB & the skin of the 1st cleft

Answer 65

Most common at head/neck of fibula, where it may be injured by fracture of fibula But it is also subcutaneous & => susceptible to direct trauma Loss of ankle & digit dorsiflexors, and evertors, causing Footdrop & loss of sensation of the lateral leg & dorsum of the foot. COMPARTMENT SYDROME = oedema & raised pressure occurring w/in any leg compartment as the result of muscle over-use or crush injury (or too tight ski boots) The pressure compromises muscle action, vascular supply & nerve supply. Passive movement causes xs pain in the affected compartment. If the deep fib is involved = loss of sensation at the 1st cleft (dorsum)

Answer 66

L4 - S3. Supplies all muscles of the superficial & deep posterior compartments Leaves the popliteal fossa, lying on popliteus, & passing deep to gastrocnemius & soleus. It divides into the medial & lateral plantar nerves deep to the flexor retinaculum (witht he post tibial artery & its venae comitantes) & they supply the skin of the sole. MED = abductor hallucis, flexors digitorum & hallucis brevis & the lumbrical to the 2nd digit LAT = all other muscles of sole (incl. quadratus plantae)

Answer 67

Due to its deep position, injury to the Tibial nerve is rare, but if it occurs, it causes loss of ankle & digit plantarflexion & loss of sensation to the sole

Answer 68

Supplies more skin than muscles in sole Equivalent to median nerve in palm Enters sole deep to Abductor Hallucis (which it supplies) & lies between abductor & FDB, which it also supplies. Ends by sending cutaneous branches to the medial sole & 3.5 digits, inc. nail beds after supplying the 1st lumbrical & FHB

Answer 69

Enters sole deep to Abductor Hallucis & then lies between FDB & quadratus plantae (which it also supplies) before emerging into the sole & dividing into deep & superficial branches. The deep branch (like the ulnar) supplies those muscles in the sole not supplied by the medial planar (remaining 3 lumbricals, all interossei, all muscles to pinky toe & adductor hallucis) Superficial branch ends by sending cutaneous branches to the lat sole & 1.5 digits, inc. nail beds

Answer 70

May be compressed deep to flexor retinaculum and/or abductor hallucis giving aching, numbness or tingling (paraesthesia) along the medial aspect of the sole (not unlike carpal tunnel syndrome)

Answer 71

Also like the ulnar, injury to the lateral plantar may cause a claw foot deformity