Subscapular nerves

Anatomy and function of the subscapular nerves

Subscapular nerves

The subscapular nerves are a group of nerves that arise from the brachial plexus and innervate the subscapularis muscle and the teres major muscle. These nerves are crucial for the movement and stabilization of the shoulder joint.

Diagram of the brachial plexus, showing the subscapular nerves.

Anatomy

The subscapular nerves originate from the posterior cord of the brachial plexus, which is formed by the union of the posterior divisions of the upper, middle, and lower trunks. Specifically, the subscapular nerves are derived from the C5 and C6 nerve roots.

There are typically two subscapular nerves:

• The upper subscapular nerve (also known as the superior subscapular nerve) innervates the upper part of the subscapularis muscle.
• The lower subscapular nerve (also known as the inferior subscapular nerve) innervates the lower part of the subscapularis muscle and the teres major muscle.

Function

The primary function of the subscapular nerves is to provide motor innervation to the subscapularis and teres major muscles. These muscles play a vital role in the movement of the shoulder joint:

• The subscapularis muscle is responsible for the internal rotation of the humerus and helps stabilize the head of the humerus in the glenoid cavity.
• The teres major muscle assists in the adduction and medial rotation of the humerus.

Clinical significance

Injury to the subscapular nerves can result in weakness or paralysis of the subscapularis and teres major muscles, leading to impaired shoulder movement. Such injuries may occur due to trauma, surgical procedures, or compression by surrounding structures.

Related pages

• Brachial plexus
• Subscapularis muscle
• Teres major muscle
• Shoulder joint