Cubital Tunnel Syndrome

Cubital Tunnel Syndrome

The majority of the general public has heard of carpel tunnel syndrome, even if they do not exactly know what it is. Carpel tunnel syndrome is an entrapment of the median nerve as it travels through the carpel tunnel. This syndrome is common knowledge because it’s the number one nerve entrapment of the upper limb. While everyone has probably at least heard of carpal tunnel syndrome, cubital tunnel syndrome (diagram) tends to be less well known but can be just as debilitating.

Anatomy of the Cubital Tunnel 

The cubital tunnel is bordered by the medial epicondyle of the humerus and the olecranon process. A tendinous arch (arcuate ligament – also known as Osborne’s ligament) that joins the humeral and ulnar heads of the flexor carpi ulnaris (FCU) forms the roof of the cubital tunnel. The floor of the cubital tunnel is comprised of the ulnar collateral ligament of the elbow joint.


What is Cubital Tunnel Syndrome?

Cubital tunnel syndrome is an entrapment of the ulnar nerve, commonly known as the funny bone, within the cubital tunnel.  As mentioned previously, both the FCU and UCL of the elbow attach to the medial epicondyle. When the elbow is bent both of these structures become taught, causing entrapment of the ulnar nerve. One study found more than 80% of cadavers had an enlarged ulnar nerve where it enters the cubital tunnel. The authors attributed this to chronic inflammation caused by repetitive bending of the elbow.

Innervation of the Ulnar Nerve

The ulnar nerve is one of the major nerves of the upper limb and provides sensory information to the pinky and half of the ring finger. The ulnar nerve also provides motor innervation to two muscles of the forearm (flexor carpi ulnaris, and the medial portion of flexor digitorum profundus), and some of the muscles of the palmar side of the hand.

Cubtial tunnel syndrome causes numbness in the light blue area in the hand.
Cubital tunnel syndrome causes numbness in the light blue area in the hand.
Signs and Symptoms of Cubital Tunnel Syndrome

Some of the signs and symptoms of cubital tunnel syndrome include pain and tingling in the elbow, ring and pinky finger. Prolonged injury to the ulnar nerve can result in significant long term disability; such as, weakness of the muscles of the ring and pinky finger and inability to pinch your thumb and pinky fingers together. Other signs and symptoms include hypothenar (blue part of the palm in the previous image) muscle wasting and claw-like deformity of the hand.

Claw-like deformity
Compression Methods of the Ulnar Nerve in Cubital Tunnel Syndrome

There are a couple ways that the ulnar nerve can be injured at the elbow; such as: direct trauma (leaning on the elbow or banging it on a desk), traction and friction. Compression is another common mechanism of cubital tunnel syndrome. The upper limb tension test of the ulnar nerve (elbow bent, wrist extended and shoulder out to the side: abducted) increases the pressure on the nerve six times compared to when the elbow, shoulder and wrist are straight. Most people aren’t aware that they are applying compression to the ulnar nerve for a prolonged period of time while they are talking on a cell phone or sleeping with their elbow bent and their hand under the pillow.

Therapeutic Interventions for Cubital Tunnel Syndrome

The majority of cases of cubital tunnel syndrome can be prevented or treated by avoiding periods of prolonged flexion of the elbow. If symptoms persists then certain treatments such as: soft tissue therapy (massage and stretch), electro-acupuncture, electrotherapy and laser can be very effective.

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