Thoracodorsal nerve

The thoracodorsal nerve also known as the middle subscapular or long subscapular nerve arises from the posterior cord of the brachial plexus and supplies the latissimus dorsi muscle.

Gross anatomy

Origin

The thoracodorsal nerve arises from the posterior cord of the brachial plexus with fibers from the sixth, seventh and eighth cervical nerves.

Course and relations

After branching from the posterior cord between the upper and lower subscapular nerves, the thoracodorsal nerve runs down the posterior axillary wall. At its origin it is posterior to the subscapular artery. However, as it descends along the posterior wall of the axilla it comes to lie anterior to the artery, then called the thoracodorsal artery.

The thoracodorsal nerve crosses the lower border of the teres major muscle and enters the deep surface of the latissimus dorsi with terminal branches of the nerve extending to the inferior border of the muscle.

Branches and supply

The thoracodorsal nerve supplies the latissimus dorsi muscle.

Variant anatomy

The thoracodorsal nerve may arise from the axillary nerve or from a common trunk with the upper and lower subscapular nerves in a small proportion of the population.

Related pathology

The thoracodorsal nerve may be damaged in surgical procedures of the lower axilla. The nerve supply is preserved in surgical flaps involving the latissimus dorsi and occasionally the nerve is harvested and grafted for facial nerve reconstruction.