Brachial Plexus

general: where derived from and what innervates

-Ventral Rami of C5-T1

-Innervation for the upper extremity (*motor and generel sensory cutaneous)

parts of a spinal nerve

-dorsal root

-ventral root

-spinal nerve: combined root; further branch to ramus

-Dorsal ramus: intrinsic back/deep back muscles

-Ventral ramus: brachial plexus

numbering spinal nerves

-There are 7 cervical vertebrae, but…

There are 8 cervical nerves (bc superior to vertebra)

*Thoracic are inferior to vertebra

axillary artery and brachial plexus relation

-axillary artery is in the middle of the plexus

-the lateral, posterior, and medial cords are named in reference to the plexus

-3 layers: blue superficial, axillary artery, posterior cord

5 sections of the brachial plexus

-roots

-trunks

-divisons (*not emphasized a lot)

-cords

-branches

“Randy Travis Drinks Cold Beer”

what are the branches of the brachial plexus

MARMU…

-musculocutaneous

-axillary

-radial

-median

-ulnar

what are the spinal cord levels that contribute to the branches from superior to inferior?

A-MU-R-Med-U; superior → inferior…

-axillary: C5, 6

-musculocutaneous: C5, 6, 7

-radial: C5,6,7,8, T1

-median: (C5), C6, 7,8, T1

-ulnar: (C7), C8, T1

“M” of the brachial plexus

axillary n

-C5-6

-Posterior cord; Posterior division;Superior Trunk

-Motor to Deltoid, Teres minor (*lateral shoulder area)

-Sensory to posterior, superior arm

musculocutaneous n

-C5-7

-Lateral cord; Anterior division; Superior and Middle Trunks

-Pierces coracobrachialis m.; Motor to anterior compartment of arm

-Sensory to lateral forearm ->lateral antebrachial cutaneous n.

radial n

-C5-T1 (*all roots)

-Posterior cord; Posterior division; All Trunks

-Motor to posterior arm and forearm

-Sensory to posterior arm, forearm, and parts of hand

*huge!

median n

-(C5)C6-T1

-Medial and Lateral cords (*only one w/ multiple cords)

-Anterior division; all Trunks

-Motor to most anterior forearm muscles, thenar muscles (*1,2,3, ~4; palmar and nailbeds)

-Sensory to lateral, palmar hand and dorsum of digits (see diagram)

ulnar n

-C8, T1

-Medial cord; Anterior division; Inferior trunk

-Motor to 2 anterior forearm muscles (FCU + FDP), intrinsic hand muscles

-Sensory to medial hand (*4 and 5)

brachial plexus injuries: upper vs lower trunk

Upper/superior trunk of plexus: Erb-Duchene Palsy

-C5, C6

-Deltoid, biceps brachii, brachialis, coracobrachialis

Lower/inferior trunk of plexus: Klumpke  paralysis (less common)

-C8, T1

-Intrinsic hand muscles–“claw hand”

compartments motion

•Lateral shoulder

•Anterior arm

•Posterior arm

•Anterior forearm

•Posterior forearm

•Anterior hand

•Posterior hand

•Abduct arm

•Flex elbow, supination

•Extend elbow

•Flex wrist and fingers, pronation

•Extend wrist and fingers, supination

•Flex fingers, adduct fingers

•Abduct fingers

damaged nerve lost action

•Axillary

•Musculocutaneous

•Radial

•Median

•Ulnar

-Abduction of shoulder (*delotid and teres minor)

-Flexion of elbow (*anterior arm)

-Extention of elbow, wrist, fingers (*post arm and forearm)

-Flexion of wrist, most fingers (*ant forearm and lat hand)

-Some wrist flexion, flexion of 2 fingers (4 and 5), adduction and abduction of fingers, weak grip (*medial side/5th)