Cubital tunnel syndrome is a condition that affects the ulnar nerve where it crosses the inside edge of the elbow. The symptoms are very similar to the pain that comes from hitting your funny bone. When you hit your funny bone, you are actually hitting the ulnar nerve on the inside of the elbow. There, the nerve runs through a passage called the cubital tunnel. When this area becomes irritated from injury or pressure, it can lead to cubital tunnel syndrome.

Anatomy

The ulnar nerve actually starts at the side of the neck, where the individual nerve roots leave the spine. The nerve roots exit through small openings between the vertebrae. These openings are called foramen.

The nerve roots join together to form three main nerves that travel down the arm to the hand. One of these nerves is the ulnar nerve.

The ulnar nerve passes through the cubital tunnel just behind the inside edge of the elbow. The tunnel is formed by muscle, ligament, and bone. You may be able to feel it if you straighten your arm out and rub the groove on the inside edge of your elbow.

The ulnar nerve passes through the cubital tunnel and winds its way down the forearm and into the hand. It supplies feeling to the little finger and half the ring finger and controls the small muscles of the hand.

Causes

Cubital tunnel syndrome has several possible causes. Part of the problem may lie in the way the elbow works. The ulnar nerve actually stretches several millimeters when the elbow is bent. Sometimes the nerve will shift or even snap over the bony medial epicondyle. (The medial epicondyle is the bony point on the inside edge of the elbow.) Over time, this can cause irritation.

One common cause of problems is frequent bending of the elbow--pulling levers, reaching, or lifting. Constant direct pressure on the elbow over time may also lead to cubital tunnel syndrome. The nerve can be irritated from leaning on the elbow while you sit at a desk or from using the elbow rest during a long drive or while running machinery. The ulnar nerve can also be damaged from a blow to the cubital tunnel.

Symptoms

Numbness on the inside of the hand and in the ring and little fingers is an early sign of cubital tunnel syndrome. The numbness may develop into pain. The numbness is often felt when the elbows are bent for long periods, such as when talking on the phone or while sleeping. The hand and thumb may also become clumsy as the muscles become affected.

Tapping or bumping the nerve in the cubital tunnel will cause an electric shock sensation down to the little finger. This is called Tinel's sign.

Symptoms sometimes seem like golfer's elbow (medial epicondylitis). In golfer's elbow, there is pain in the funny bone area of the elbow.