LECTURE 9 brachial plexus and nerve damage Flashcards
description of brachial plexus
lies partly in neck and partly in axilla, gives rise to almost all nerves that supply upper limb, formed by intermixing of ventral rami of spinal nerves C5-C8 and T1 (cervial enlargement)
mnemonic devise to remember brachial plexus divisions
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how many ventral rami in the brachial plexus?
5
how many trunks in brachial plexus?
3
how many divisions in brachial plexus?
2
how many cords in brachial plexus?
3
how many branches in brachial plexus?
many
ventral rami in brachial plexus
C5-8, T1
trunks in brachial plexus
upper/superior trunk (from C5-C6), middle trunk (from C7), lower trunk (from C8-T1)
where do rami join to form trunks in brachial plexus?
neck
divisions in brachial plexus
anterior and posterior (for each trunk)
where do trunks split to form divisions in brachial plexus?
neck
cords in brachial plexus
lateral (anterior upper division, anterior middle division), medial (anterior lower division), posterior (posterior upper division, posterior middle division, posterior lower division) (relative to position to axillary artery)
where do divisions join to form cords in brachial plexus?
axilla
where do cords give off branches in brachial plexus?
axilla
branches of brachial plexus
musculocutaneous nerve (lateral cord), median nerve (lateral and medial cord), ulnar nerve (medial cord), radial nerve (posterior cord), axillary nerve (posterior cord), thoracodorsal nerve (posterior cord), subscapularis nerve (posterior cord)
description of musculocutaneous nerve
from lateral cord, somatic motor, runs on lateral side of arm providing branches to muscles in anterior compartment of arm (coracobrachialis M, biceps brachii M, brachialis M), continues into forearm to provide cutaneous innervation (skin of lateral forearm S)
description of ulnar nerve
from medial cord, runs along medial side of arm but does not give off any branches, passes posterior to medial epicondyle and runs along the ulna to supply 2 muscles in anterior compartment of forearm (flexor carpi ulnaris M, half of flexor digitorum profundus M), runs into the hand superficial to the carpal tunnel (most intrinsic hand muscles M, skin of medial 2/3 of hand S)
description of median nerve
from lateral and medial cords, runs through the middle of the arm but does not give off any branches, continues into the forearm to provide branches to most forearm flexors (all flexor muscles but 2 M, pronator teres and quadratus M), runs into the hand by passing inside carpal tunnel (some intrinsic hand muscles including thenar group M, skin on 2/3 lateral palm and dorsum of fingers 2 and 3 S)
description of radial nerve
from posterior cord, largest nerve in brachial plexus, runs through the arm to supply muscles of posterior compartment of arm (triceps brachii M), continues around the lateral epicondyle and divides into superficial and deep branches (deep branch: all muscles of posterior forearm M, superficial branch: skin of dorsolateral arm and forearm and most of dorsolateral surfaces of hand S)
description of axillary nerve
from posterior cord, runs posterior to humerus to supply: deltoid muscles M, teres minor mucles M, capsule of shoulder and skin of shoulder S
description of subscapular nerve
from posterior cord, supplies subscapularis muscle M, teres major muscle M
description of thoracodorsal nerve
from posterior cord, runs with thoracodorsal artery and vein to supply latissimus dorsi muscle M
nerve damage to ulnar nerve
“claw hand”: inability to extend fingers at interphalangeal joints, results in permanent flexion of hand
nerve damage to median nerve
“ape hand”: inability to oppose thumb
nerve damage to radial nerve
“wrist drop”: inability to extend the hand, inability to fully extend forearm
