Posterior cord of brachial plexus

The posterior cord of brachial plexus arises from the posterior divisions of the superior, middle, and inferior trunks of the plexus. It is part of the infraclavicular portion of the brachial plexus and is situated within the axilla, where it lies posterior to the third part of the axillary artery.

Branches of the posterior cord of brachial plexus

The posterior cord gives rise to the following important branches:

• Upper subscapular nerve (C5, C6): Innervates the subscapularis muscle.

• Lower subscapular nerve (C5, C6): Supplies the subscapularis and teres major muscles.

• Thoracodorsal nerve (C6, C7, C8): Innervates the latissimus dorsi muscle.

• Axillary nerve (C5, C6): Supplies the deltoid (responsible for shoulder abduction) and the teres minor (a rotator cuff muscle). It also provides sensation to the lateral shoulder via the superior lateral cutaneous nerve of the arm.

• Radial nerve (C5-T1): Innervates all extensor muscles of the arm and forearm, including the triceps brachii and the extensors of the wrist and fingers. It also supplies sensory input to the posterior arm, forearm, and hand, including the dorsal aspect of the lateral 3½ fingers (except the fingertips).