Brachial plexus – part 2.

In part 1 the roots, trunks, divisions and branches are covered. Here I will be looking at the structures supplied by the branches.

upper extremity peripheral innervation

Root nerves:

Dorsal scapular (C5) – Rhomboid major, rhomboid minor and levator scapulae.
Long thoracic (C5, 6, 7) – Serratus anterior.

Superior trunk nerves:

Subclavian (C5, 6) – Subclavius.
Suprascapular (C5, 6) – Supraspinatus, infraspinatus.

Lateral cord nerves:

Lateral pectoral (C5, 6, 7) – Pectoralis major.
Musculocutaneous (C5, 6, 7) – Biceps brachii, coracobrachialis, brachialis.

musculocutaneous nerve

Posterior cord nerves:

Upper subscapular (C5, 6) – Subscapularis.
Lower subscapular (C5, 6) – Subscapularis.
Thoracodorsal (C6, 7, 8) – Lattisimus dorsi.
Axillary (C5, 6) – Deltoid, teres minor.
Radial (C5 – T1) – Triceps brachii, supinator, anconeus, brachioradialis, extensor carpi radialis.


Medial cord nerves:

Medial pectoral (C8, T1) – Pectoralis major, pectoralis minor.
Ulnar nerve (C8, T1) – Flexor carpi ulnaris, flexor digitorum profundus, LOAF of the hands.

ulnar nerve

*Median nerve receives branches from the lateral (C6, 7) and medial cords (C8, T1) – Pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis, flexor digitorum profundus, flexor policis longus, pronator quadratus.


The brachial plexus also has dermatomes:

brachial dermatomes

Major nerves of the brachial plexus.

Median nerve (C5) C6 – T1.
– Through anterior compartment of arm.
– Lateral to brachial artery (medial arm).
– Crosses to medial side of brachial artery.
– Cubital fossa (anterior elbow).
– Between the two heads of pronator teres. Overworked??
– Between flexor digitorum superficialis and profundus.
– Superficial proximal to wrist.
– Through carpal tunnel.

Radial nerve C5 – C8 (T1).
– Back of arm, same with hand.
– Posterior axilla, behind artery.
– Posterior compartment of arm.
– Between long and medial head of triceps.
– Through radial groove (posterior humerus).
– Pierces intermuscular septum.
Enters anterior compartment.
Anterior elbow.
2 branches:
Superficial: anterolateral forearm.
Deep: posterior forearm.



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