BIO2300 Unit 3 Brachial Plexus of Nerves

when identifying the branches of the medial and lateral cords look for this identifying feature

"m" nerve

when identifying the axillary and radial nerve you should look for the

"y" nerve

the radial nerve motor innervation consists of which muscles

- all posterior arm muscles - all posterior forearm muscles

what are the 2 divisions of the brachial trunks?

- anterior - posterior

motor innervation of the median nerve

- anterior forearm (excepting a few muscles) thenar muscles

name the 2 structures each spinal nerve branches into

- anterior ramus - posterior ramus

the posterior cord branches distally into what two nerves

- axillary - radial

physical signs/symptoms that the axillary nerve is injured

- decreased ability to abduct at shoulder - overall weakness in shoulder movement

physical signes/symptoms that the radial nerve is injured

- decreased ability to perform extension at the elbow, wrist & digits - "wrist drop"

the axillary nerve motor innervation consists of which muscles

- deltoid - teres minor

each of the 3 trunks of the brachial plexus branches ____________ into 2 _____________

- distally - divisions

motor innervation of the ulnar nerve

- flexor carpi ulnaris - medial 1/2 of flexor digitorum profundis

the few anterior muscles not innervated by the median nerve

- flexor carpi ulnaris - medial 1/2 of flexor digitorum profundis

cutaneous innervation of the median nerve

- lateral 3.5 digits & associated palm - posterior tips of same fingers

cutaneous innervation of the ulnar nerve

- medial 1.5 digits - associated palmar and dorsal surfaces of the hand

path of the ulnar nerve

- passes posterior to medial epicondyle - travels along medial forearm - into the hand (outside of the carpal tunnel)

path of the musculocutaneous nerve

- pierces coracobrachialis muscle - deep to biceps brachii

the radial nerve cutaneous innervation consists of

- posterior arm - posterior forearm - posterior hand & lateral 3.5 digits

the 3 cords of the anterior and posterior divisions are

- posterior cord - lateral cord - medial cord

list the 5 segments of the brachial plexus

- roots - trunks - divisions - cords - terminal branches

list the 3 trunks of the brachial plexus

- superior trunk - middle trunk - inferior trunk

path of the median nerve

- through the cubital fossa - through the carpal tunnel at the wrist

physical signs/symptoms that the median nerve is injured

- weakness in hand grip & opposition in thumb - abnormal sensation in lateral 3.5 digits

the total number of anterior divisions of each brachial plexus

3

the total number of posterior divisions of each brachial plexus

3

which nerve roots communicate with the superior trunk of the brachial plexus

C5 & 6

brachial plexus is aka

C5 - T1 anterior rami

which nerve root communicates with the middle trunk of the brachial plexus

C7

which nerve roots communicate with the inferior trunk of the brachial plexus

C8 & T1

motor innervation of the musculocutaneous nerve

all anterior arm muscles

the anterior division of the brachial plexus builds nerves for the ___________ _______________ of the upper limbs

anterior compartment

the plexus is composed of a collection of multiple ______________ ________________ which innervate the upper and lower limbs

anterior rami

a bundle of nerves which connects the spinal cord to the upper limbs

brachial plexus

impingement of medial nerve at the flexor retinaculum results in

carpal tunnel

what function do the terminal branches of the brachial plexus perform

carry named nerves to & from upper limb structures

signs/symptoms if the musculotaneous nerve is injured

decreased ability to perform flexion & supination at elbow

ulnar nerve is aka

funny bone nerve

origin of the median nerve

lateral & medial cord

origin of the musculocutaneous nerve

lateral & medial cord

cutaneous innervation of the musculocutaneous nerve

lateral forearm

origin of the ulnar nerve

medial cord

both the lateral and medial cord branch together distally into what combined structure

median nerve (Me)

the lateral cord forms what nerve as it branches distally

musculocutaneus nerve (Mu)

path of the radial nerve

passes posterior to the humerus w/in the radial groove

path of the axillary nerve

passes posterior to the surgical neck of the humerus

both the axillary and radial nerve pass ___________________ to the humerus

posterior

the posterior division of the brachial plexus builds nerves for the ___________ _______________ of the upper limbs

posterior compartment

origin of the axillary nerve

posterior cord

origin of the radial nerve

posterior cord

which portion of the brachial plexus is most proximal

roots

the axillary nerve cutaneous innervation consists of

superolateral arm superficial to the deltoid

which portion of the brachial plexus is most distal

terminal branches

the medial consists of

the anterior division of the inferior trunk

the lateral cord consists of

the anterior division of the superior & middle trunk

the posterior cord consist of

the posterior division of all 3 trunks

the brachial plexus segments into 3 seperate _____________

trunks

the medial cord forms what nerve as it branches distally

ulnar nerve

what nerve is not a part of carpal tunnel syndrom

ulnar nerve