Internal Cutaneous nerve arises from the inner cord of the brachial plexus. In the upper part of its course it lies superficial to the artery and the ulnar nerve. It then pierces the deep fascia about the middle of the inner side of the arm, and accompanies the basilic vein to the elbow, where it divides into its two terminal branches.

Branches

In the upper arm a branch which supplies the lower half of the anterior surface on its inner side.

In the forearm there are two branches - one supplies the anterior surface of the inner side of the forearm as far as the wrist, the other supplies the upper three-fourths of the posterior surface of the inner side.

Lesser Internal Cutaneous arises from the inner cord of the brachial plexus. It supplies the skin of the upper half of the arm on the inner side.

Circumflex nerve from the posterior cord passes down behind the axillary artery and goes through the quadrilateral space in company with the posterior circumflex artery. It winds round the surgical neck of the humerus and ends in the deltoid (see Fig. 6).

Branches

Muscular to the teres minor and deltoid muscles.

Articular to the shoulder-joint.

Cutaneous to the skin over the deltoid and upper half of the arm.