upper limb nerves

Question 1

draw the brachial plexus

Answer 1

C5-6: superior
C7: middle
C8-T1: inferior

superior+middle: lateral
superior+middle+inferior: posterior
inferior: medial

lateral: musculocutaneous
posterior: axillary
posterior: radial
lateral + medial: median
medial: ulnar

Question 2

types of sympathetic fibres

Answer 2

1. sudomotor: smooth muscle around sweat glands
2. vasomotor: smooth muscle around vesicles
3. pilomotor: arrector pili around hair follicles

Question 3

somatic vs visceral nerve fibre innervation

Answer 3

somatic: efferent innervates skeletal muscle, afferent innervates somatic tissue

visceral: efferent and afferent innervate visceral organs

Question 4

branches of the lateral cord (LML)

Answer 4

lateral pectoral nerve, musculocutaneous nerve, lateral root of median nerve

Question 5

branches of the posterior cord (ULNAR)

Answer 5

upper subscapular nerve (suprascapular), lower subscapular nerve, nerve to latissimus dorsi (thoracodorsal), axillary nerve, radial nerve

Question 6

branches of the medial cord (M4U)

Answer 6

medial root of median nerve, medial pectoral nerve, medial cutaneous nerve of the arm, medial cutaneous nerve of the forearm, ulnar nerve

Question 7

axillary nerve supply

Answer 7

comes from the posterior cord –> (axilla) supplies shoulder joint via articular branch –> (arm) anterior branch: winds around surgical neck to supply deltoid and skin (regimental patch) + posterior branch: supplies teres minor

Question 8

musculocutaneous nerve supply

Answer 8

arises from the lateral cord –> (axilla) supplies coracobrachialis –> (arm) supplies biceps brachii and brachialis, lateral to the biceps tendon –> (forearm) sensory supply as the lateral cutaneous nerve of the forearm

Question 9

radial nerve innervation

Answer 9

arises from posterior cord –> (axilla) lies behind axillary artery –> (arm) enters the posterior compartment of the arm along the radial groove, supplying triceps and gives off posterior cutaneous nerve + enters the anterior compartment of the arm above the lateral epicondyle, supplying brachioradialis and brachialis –> (forearm) passes through cubital fossa to divide into superficial and deep branches, deep branch supplies supinator and posterior aspect of forearm (extensors) –> (hand) superficial branch runs lateral to radial artery, supplies lateral 2/3 of dorsum of hand + lateral 1.5 fingers + dorsum of thumb

Question 10

median nerve innervation

Answer 10

no branches in axilla –> (arm) runs lateral to brachial artery, then crosses the brachial artery to run medial to it –> (forearm) leaves the cubital fossa between the heads of the pronator teres to supply the anterior aspect of arm (flexors), entering the palm via carpal tunnel –> (hand) gives off superficial branch to supply thenar eminence, supplies LOAF (lumbricals 1 and 2, opponens pollicis, abductor pollicis brevis, flexor pollicis brevis)

Question 11

ulnar nerve innervation

Answer 11

arises from medial cord, descending between axillary artery and vein –> (arm) runs medial to brachial artery and enters posterior compartment of arm behind the medial epicondyle to supply the elbow –> (forearm) enters the forearm between flexor carpi ulnaris and flexor digitorum profundus, medial to ulnar artery –> (hand) enters the palm in front of the flexor retinaculum to supply medial side of dorsum of the hand, medial 1.5 fingers, hypothenar muscles, adductor pollicis, lumbricals 3 and 4, interossei

Question 12

Erb Duchenne Palsy cause and presentation

Answer 12

cause: damage to the superior trunk (C5+C6) affecting musculocutaneous, axillary and (upper subscapular) suprascapular nerve

presentation: “waiter’s tip” position, lost bicep reflex, paralysed supraspinatus, deltoid, biceps, brachialis, teres minor, infraspinatus, brachioradialis, loss of sensation of lateral side of arm and forearm

Question 13

Klumpke Palsy cause and presentation

Answer 13

cause: excessive abduction of the arm, damaging C7, C8 and T1 and damaging ulnar and median nerves

presentation: clawed hand (hyperextension of MCPJ + flexion of interphalangeal joints), paralysed lumbricals and interossei, loss of ulnar reflex, loss of sensation over medial side of arm

Question 14

axilla nerve lesion cause and presentation

Answer 14

cause: damage to C5-6 caused by pressure of crutch onto armpit / downward displacement of humerus in shoulder dislocation / fracture of surgical neck of humerus

presentation: unable to abduct arm past 15°, paralysis of deltoid and teres minor, loss of skin sensation over lower half of deltoid

Question 15

musculocutaneous nerve lesion presentation

Answer 15

well protected by the biceps and brachialis hence almost never injured

presentation: flexion at elbow and supination of forearm weakened

Question 16

radial nerve axilla lesion presentation

Answer 16

wrist drop + unable to extend elbow joint, wrist joint, fingers, paralysed triceps, anconeus, extensor muscles of forearm, brachioradialis, supinator, loss of sensation at the posterior part of the forearm + lateral dorsum of hand + lateral 3.5 fingers

Question 17

radial nerve mid arm lesion presentation

Answer 17

wrist drop occurs, unable to extend wrist or fingers, weakened triceps, paralysed brachioradialis, supinator, extensor muscles, loss of sensation on lateral dorsum of hand and lateral 3.5 fingers

Question 18

radial nerve wrist lesion presentation

Answer 18

can’t extend thumb and MCPJ (damage to the deep branch of the radial nerve), superficial branch of radial nerve is fine so extensors are ok and wrist drop does not occur

Question 19

ulnar nerve elbow lesion presentation

Answer 19

likely due to a fracture posterior to medial epicondyle

claw hand in 4th and 5th fingers (MCPJ hyperextended and interphalangeal joints flexed due to paralysed lumbricals and interosseous muscles) + inability to make a fist (FCU and medial 1/2 of FDP paralysed) + inability to adduct and abduct fingers (paralysis of muscles of hand)

loss of sensation over medial 1/3 of hand and medial 1.5 fingers

Question 20

ulnar nerve wrist lesion presentation

Answer 20

likely due to lacerations

ulnar paradox = more observable claw hand (FDP not paralysed so terminal phalanges can be flexed), small muscles of the hand are paralysed, Froment’s sign (paralysis of adductor pollicis causes abnormal adduction of the thumb, patients can’t clip a paper between the thumb and index finger without opposition)

loss of sensation on medial 1/3 of palm and medial 1.5 fingers

Question 21

median nerve elbow lesion presentation

Answer 21

loss of pronation (paralysis of anterior forearm muscles), wrist flexion weak and requires adduction (FCU working), “hand of benediction” (lateral 3 fingers cannot be flexed but medial 2 flex weakly), “ape hand” (thumb is laterally rotated and adducted due to paralysis and wasting of thenar muscles)

loss of sensation on palmar aspects of lateral 3.5 fingers

Question 22

median nerve wrist lesion cause and presentation

Answer 22

cause: compression of the nerve in the carpal tunnel, may be worse in the morning due to increased pressure in the carpal tunnel (after lying down)

presentation: carpal tunnel syndrome
burning sensation + tingling over lateral 3.5 fingers, weakness of thenar muscles, loss of opposition and abduction of thumb

Question 23

nerve roots of upper limb reflex arcs

Answer 23

biceps: C5-6 (biceps brachii tendon reflex)
triceps: C7-8 (triceps tendon reflex)
brachioradialis: C5-6
finger adduction: T1
lumbricals: C7

Question 24

tap on yourself the dermatome testing points for nerve roots C5-T1

Answer 24

C5: lateral arm
C6: thumb
C7: index finger
C8: pinky finger
T1: medial forearm

Question 25

supply of the axillary artery (right vs left upper limb)

Answer 25

right: aorta --> brachiocephalic --> subclavian --> axillary left: aorta --> subclavian --> axillary

Question 26

branches of the axillary artery

Answer 26

Screw The Lawyer Save A Patient + Brachial :) superior thoracic, thoracoacromial, lateral thoracic, subscapular, anterior circumflex, posterior circumflex, brachial (terminal branch)

Question 27

anastomoses within the upper arm

Answer 27

-suprascapular and superficial cervical arteries anastamose with subscapular artery -(ant and post) circumflex humeral arteries anastamose around the surgical neck of the humerus

Question 28

pathway of the brachial artery

Answer 28

originates from axillary artery at the lower border of teres major --> gives off profunda brachii artery at the posterior compartment of upper arm --> gives off superior ulnar collateral artery at the posterior compartment of upper arm --> gives off inferior ulnar collateral artery and deep artery to supply anastomosis of elbow joint --> main branch supplies anterior compartment of upper arm and bifurcates into radial + ulnar arteries at cubital fossa

Question 29

pathway of the ulnar artery

Answer 29

originates from brachial artery at cubital fossa --> runs on medial side of arm, deep to flexor muscles --> gives rise to common interosseous artery (branches into anterior and posterior interosseous arteries) --> enters hand anterior to flexor retinaculum at the Guyon canal (between pisiform and hook of hamate) --> gives rise to superficial palmar arch (which anastomoses with deep palmar arch to supply the hand)

Question 30

pathway of the radial artery

Answer 30

originates from the brachial artery at the cubital fossa --> runs on the lateral side of arm under brachioradialis muscle --> enters the hand at the anatomical snuffbox --> forms deep palmar arch (which anastamoses with superficial palmar arch to supply the hand)

Question 31

pulse taking locations in the upper limb

Answer 31

axillary pulse: high up in the axilla brachial pulse: palpated in the bicipital groove radial pulse: lateral side of wrist (between FCR and brachioradialis) or anatomical snuffbox ulnar pulse: medial side of wrist (between FDS and FCU)

Question 32

veins responsible for venous drainage of upper limb

Answer 32

deep veins: venae commitantaes (accompany large arteries), axillary vein superficial veins (from the dorsal venous network in the hand): cephalic vein, basilic vein

Question 33

pathway of the cephalic vein

Answer 33

ascends from the lateral aspect of the dorsal venous network --> proceeds along lateral wrist to anterolateral surface of forearm --> communicates with the median cubital vein at the cubital fossa --> continues along the lateral side of the upper arm, between the deltoid and pectoralis major at the deltopectoral groove --> pierces the clavipectoral fascia, reaching the infraclavicular fossa and draining into the axillary vein --> drains into the subclavian vein

Question 34

pathway of the basilic vein

Answer 34

ascends from the medial end of the dorsal venous network in the hand --> proceeds along the medial inferior side of the arm --> joins the median cubital vein at the cubital fossa --> ascends the medial upper arm, piercing the brachial fascia at the teres major and joining the venae commitantaes of the brachial artery to form the axillary vein --> drains into subclavian vein

Question 35

which veins are best for venipuncture?

Answer 35

cephalic vein: immediately posterior to the styloid process of the radius median cubital vein: lies in the cubital fossa and separated from the brachial artery by the bicipital aponeurosis (drugs don't get immediately introduced into the artery)

Question 36

which veins are best for catheterisation?

Answer 36

basilic vein: increases in diameter moving upwards, is in direct line with the axillary vein

Question 37

groups of axillary lymph nodes + locations

Answer 37

apical: along medial side of axillary vein central: deep to pectoralis minor anterior: lower border of pectoralis minor posterior: in front of subscapularis lateral: lateral wall of axilla

Question 38

drainage pathway of axillary lymph nodes

Answer 38

central + anterior + posterior + lateral drain into apical group --> forms subclavian lymph trunk --> drains into thoracic duct (left side) or right lymphatic trunk (right side)