Inferior subscapular nerve

At a glance

English

Inferior subscapular nerve

Latin (TA2)

Nervus subscapularis inferior

System

Nerve

Region

Upper limb

Side

Paired, left and right

About the inferior subscapular nerve

The inferior, or lower, subscapular nerve is one of the short branches given by the posterior cord of the brachial plexus in the axilla. It carries fibres from the fifth and sixth cervical spinal nerves and leaves the cord behind the axillary artery, below the superior subscapular nerve and near the origin of the thoracodorsal nerve.

It runs downwards and laterally across the lower part of the front of subscapularis, on the posterior wall of the axilla, accompanied by branches of the subscapular artery. It sends one or more twigs into the lower portion of subscapularis and then continues to the lateral border of the scapula, where it ends in teres major. Sometimes a separate branch of the posterior cord or of the axillary nerve supplies teres major instead.

Both muscles it serves rotate the arm medially at the shoulder, and teres major also helps to pull the raised arm down and back. Isolated injury of this nerve is uncommon, because it lies deep on the posterior axillary wall, but it can be affected with the other posterior cord branches in traction injuries of the plexus or during surgery that clears lymph nodes from the axilla. Weak medial rotation from its loss is usually masked by pectoralis major and latissimus dorsi, which share that action.

Course and supply

Arises from

Posterior cord of the brachial plexus (C5, C6) in the axilla, behind the axillary artery.

Ends in

Ends in the lower part of subscapularis and in teres major.

Supplies

Motor to the lower part of subscapularis and to teres major, which rotate the arm medially; teres major also adducts and extends it.