LECTURE 9 brachial plexus and nerve damage

Question 1

description of brachial plexus

Answer 1

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)

Question 2

mnemonic devise to remember brachial plexus divisions

Answer 2

Really Tired? Drink Coffee Buddy!

Question 3

how many ventral rami in the brachial plexus?

Answer 3

5

Question 4

how many trunks in brachial plexus?

Answer 4

3

Question 5

how many divisions in brachial plexus?

Answer 5

2

Question 6

how many cords in brachial plexus?

Answer 6

3

Question 7

how many branches in brachial plexus?

Answer 7

many

Question 8

ventral rami in brachial plexus

Answer 8

C5-8, T1

Question 9

trunks in brachial plexus

Answer 9

upper/superior trunk (from C5-C6), middle trunk (from C7), lower trunk (from C8-T1)

Question 10

where do rami join to form trunks in brachial plexus?

Answer 10

neck

Question 11

divisions in brachial plexus

Answer 11

anterior and posterior (for each trunk)

Question 12

where do trunks split to form divisions in brachial plexus?

Answer 12

neck

Question 13

cords in brachial plexus

Answer 13

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)

Question 14

where do divisions join to form cords in brachial plexus?

Answer 14

axilla

Question 15

where do cords give off branches in brachial plexus?

Answer 15

axilla

Question 16

branches of brachial plexus

Answer 16

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)

Question 17

description of musculocutaneous nerve

Answer 17

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)

Question 18

description of ulnar nerve

Answer 18

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)

Question 19

description of median nerve

Answer 19

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)

Question 20

description of radial nerve

Answer 20

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)

Question 21

description of axillary nerve

Answer 21

from posterior cord, runs posterior to humerus to supply: deltoid muscles M, teres minor mucles M, capsule of shoulder and skin of shoulder S

Question 22

description of subscapular nerve

Answer 22

from posterior cord, supplies subscapularis muscle M, teres major muscle M

Question 23

description of thoracodorsal nerve

Answer 23

from posterior cord, runs with thoracodorsal artery and vein to supply latissimus dorsi muscle M

Question 24

nerve damage to ulnar nerve

Answer 24

“claw hand”: inability to extend fingers at interphalangeal joints, results in permanent flexion of hand

Question 25

nerve damage to median nerve

Answer 25

“ape hand”: inability to oppose thumb

Question 26

nerve damage to radial nerve

Answer 26

“wrist drop”: inability to extend the hand, inability to fully extend forearm