Cubital Tunnel Syndrome

Anatomy of the Cubital Tunnel

At the elbow, the ulnar nerve passes through a bony groove known as the cubital tunnel. It is bound by bone on either side, the medial epicondyl above and the olecranon (elbow) below. The tunnel has a bony base and a ligament that crosses above the ulnar nerve from the medial epicondyle to the olecranon. The illustration below shows the ulnar nerve on the inside of the right elbow, where it passes through the cubital tunnel.

The ulnar nerve, which is about the size of a pencil, controls the muscles for grip strength, primarily in the little, ring and often the middle fingers. It controls the muscles for most of the pinch strength and it controls the small muscles in the hand that coordinate fine movements of the hand, with the exception of the muscles that lift the thumb up and out of the palm and turn the thumb for pinching. The ulnar nerve also controls the feeling in the little and ring fingers, and on the little finger side of the back of the hand.