upper limb nerves Flashcards
draw the brachial plexus
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
types of sympathetic fibres
- sudomotor: smooth muscle around sweat glands
- vasomotor: smooth muscle around vesicles
- pilomotor: arrector pili around hair follicles
somatic vs visceral nerve fibre innervation
somatic: efferent innervates skeletal muscle, afferent innervates somatic tissue
visceral: efferent and afferent innervate visceral organs
branches of the lateral cord (LML)
lateral pectoral nerve, musculocutaneous nerve, lateral root of median nerve
branches of the posterior cord (ULNAR)
upper subscapular nerve (suprascapular), lower subscapular nerve, nerve to latissimus dorsi (thoracodorsal), axillary nerve, radial nerve
branches of the medial cord (M4U)
medial root of median nerve, medial pectoral nerve, medial cutaneous nerve of the arm, medial cutaneous nerve of the forearm, ulnar nerve
axillary nerve supply
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
musculocutaneous nerve supply
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
radial nerve innervation
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
median nerve innervation
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)
ulnar nerve innervation
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
Erb Duchenne Palsy cause and presentation
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
Klumpke Palsy cause and presentation
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
axilla nerve lesion cause and presentation
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
musculocutaneous nerve lesion presentation
well protected by the biceps and brachialis hence almost never injured
presentation: flexion at elbow and supination of forearm weakened
radial nerve axilla lesion presentation
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
radial nerve mid arm lesion presentation
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
radial nerve wrist lesion presentation
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
ulnar nerve elbow lesion presentation
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
ulnar nerve wrist lesion presentation
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
median nerve elbow lesion presentation
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
median nerve wrist lesion cause and presentation
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
nerve roots of upper limb reflex arcs
biceps: C5-6 (biceps brachii tendon reflex)
triceps: C7-8 (triceps tendon reflex)
brachioradialis: C5-6
finger adduction: T1
lumbricals: C7
tap on yourself the dermatome testing points for nerve roots C5-T1
C5: lateral arm
C6: thumb
C7: index finger
C8: pinky finger
T1: medial forearm
supply of the axillary artery (right vs left upper limb)
right: aorta –> brachiocephalic –> subclavian –> axillary
left: aorta –> subclavian –> axillary
branches of the axillary artery
Screw The Lawyer Save A Patient + Brachial :)
superior thoracic, thoracoacromial, lateral thoracic, subscapular, anterior circumflex, posterior circumflex, brachial (terminal branch)
anastomoses within the upper arm
-suprascapular and superficial cervical arteries anastamose with subscapular artery
-(ant and post) circumflex humeral arteries anastamose around the surgical neck of the humerus
pathway of the brachial artery
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
pathway of the ulnar artery
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)
pathway of the radial artery
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)
pulse taking locations in the upper limb
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)
veins responsible for venous drainage of upper limb
deep veins: venae commitantaes (accompany large arteries), axillary vein
superficial veins (from the dorsal venous network in the hand): cephalic vein, basilic vein
pathway of the cephalic vein
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
pathway of the basilic vein
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
which veins are best for venipuncture?
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)
which veins are best for catheterisation?
basilic vein: increases in diameter moving upwards, is in direct line with the axillary vein
groups of axillary lymph nodes + locations
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
drainage pathway of axillary lymph nodes
central + anterior + posterior + lateral drain into apical group –> forms subclavian lymph trunk –> drains into thoracic duct (left side) or right lymphatic trunk (right side)
