Ulnar nerve entrapment occurs when the ulnar nerve in the arm becomes compressed or irritated. The ulnar nerve is one of the three main nerves in your arm. It travels from your neck down into your hand, and can be constricted in several places along the way. Depending upon where it occurs, this pressure on the nerve can cause numbness or pain in your elbow, hand, wrist, or fingers.

Sometimes the ulnar nerve gets compressed at the wrist, beneath the collarbone, or as it comes out of the spinal cord in the neck. The most common place where the nerve gets compressed is behind the elbow.

When the nerve compression occurs at the elbow, it is called "cubital tunnel syndrome."

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