brachial plexus

Question 1

axillary nerve

Answer 1

roots: C5-C6
pathway/landmark: runs with posterior circumflex humeral artery arounf the surgical neck of humerus
muscles innervated; deltoid and teres minor

Question 2

radial nerve

Answer 2

C5-T1
pathway/landmark: runs posteriorly through the radial groove of the humerus to the posterior arm, divides into deep radial nerve and posterior interosseous nerve as it enters forearm
muscles innervated:
brachioradialis
all muscles of porterior arm and forearm:
lateral head of triceps brachii
long head of triceps brachii
medial head of triceps brachii
supinator
extensor carpi radialis
abductor pollicis longus
extensor digiti minimi
extensor digitorum
extensor pollicis longus
extensor pollicis brevis
extensor indicis

Question 3

musculocutaneous nerve

Answer 3

roots: C5-C7
pathway: pierces through coracobrachialis to enter anterior compartment of arm, runs between biceps brachii and brachialis
becomes lateral antebrachial cutaneous nerve in forearm

muscles innervated:
coracobrachialis
biceps brachii
brachialis

away from body side of forearm if arm facing anterior (front)

Question 4

ulnar nerve

Answer 4

roots: C8, T1
pathway: descends medial arm, runs posteriorly in groove between olecranon process and medial epicondyle and enters forearm (funny bone)

innervates:
forarm: flexor carpi ulnaris
and 1/2 of flexor digitroum profundus (medial half)
all muscles not innervated by median nerve:
adductor pllicis
dorsal interossei
palmar interossei
medial two lumbricals (4 and 5)
hypothenar muscles- opponens digit minimi, flexor digiti minimi, abductor digiti minimi

Question 5

median nerve

Answer 5

C6-T1
pathway: runs through carpal tunnel to reach hand

muscles innervated:
forearm (all muscles of anterior compartment of forearm NOT innervated by ulnar nerve):
pronator teres
flexor carpi radialis
palmaris longus
flexor digitorum superficialis
flexor policis longus
pronator quadratus
3 thenor muscles
lumbrical digits 2, 3

muslces of hand:
1/2 lumbricals (lateral 2)
opponens pollicis
abductor pollicis brevis
flexor pollicis brevis

Question 6

proximal to distal gradient of innervation

Answer 6

nerves supplied by proximal rami (C5-C6) innervate proximal muscles
intermediate (C6-C8) supply elbow and wrist
inferior fibers (C8-T1) innervates distal- hand anf forearm