Upper subscapular nerve

Upper Subscapular Nerve

The upper subscapular nerve is a nerve that arises from the posterior cord of the brachial plexus. It is responsible for innervating the upper part of the subscapularis muscle, which is one of the muscles of the rotator cuff in the shoulder.

Anatomy

The upper subscapular nerve originates 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. It typically arises from the fifth and sixth cervical nerves (C5 and C6).

Diagram of the brachial plexus, showing the origin of the upper subscapular nerve.

The nerve travels posteriorly and enters the subscapularis muscle, providing motor innervation to its upper portion. The subscapularis muscle is located on the anterior surface of the scapula and plays a crucial role in the internal rotation of the arm.

Function

The primary function of the upper subscapular nerve is to supply motor innervation to the upper part of the subscapularis muscle. This muscle is involved in the internal rotation of the humerus and stabilization of the shoulder joint.

Clinical Significance

Injury to the upper subscapular nerve can result in weakness or paralysis of the subscapularis muscle, leading to difficulties in internally rotating the arm. Such injuries may occur due to trauma, surgical procedures, or compression by surrounding structures.

Related Structures

The upper subscapular nerve is closely associated with other nerves of the brachial plexus, including the lower subscapular nerve and the thoracodorsal nerve. These nerves also contribute to the innervation of the shoulder and upper back muscles.

The brachial plexus, with the upper subscapular nerve highlighted.

Related Pages

• Brachial plexus
• Subscapularis muscle
• Rotator cuff
• Shoulder joint

References

• Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2013). Clinically Oriented Anatomy. 7th edition. Lippincott Williams & Wilkins.
• Standring, S. (2015). Gray's Anatomy: The Anatomical Basis of Clinical Practice. 41st edition. Elsevier.

The subscapularis muscle, innervated by the upper subscapular nerve.