Guyon Canal Syndrome

Excerpt

Guyon canal syndrome is a relatively rare peripheral ulnar neuropathy that involves injury to the distal portion of the ulnar nerve as it travels through a narrow anatomic corridor at the wrist. The ulnar nerve originates from C8-T1 and is a terminal branch of the brachial plexus. In the upper arm, the ulnar nerve courses posterior and medial to the brachial artery, and heads for the posterior aspect of the elbow, piercing the medial intermuscular (IM) septum at the arcade of Struthers. The nerve pierces the medial IM septum approximately 8 cm proximal to the medial epicondyle.

The ulnar nerve enters the cubital tunnel posterior to the medial epicondyle and enters the forearm by piercing between the two heads of the flexor carpi ulnaris (FCU) muscle. The ulnar nerve reaches the hand via Guyon canal to provide motor and sensory innervation to the digits. Guyon canal is a unique location where the ulnar nerve is vulnerable to compressive injury, although the more common location of the ulnar nerve injury occurs at the elbow which is known as cubital tunnel syndrome.

The anatomic boundaries of Guyon canal include:

1. Volar carpal ligament - the "roof"

2. Transverse carpal ligament - the "floor"

   1. Note that the transverse carpal ligament spans Guyon canal as the floor at the ulnar side of the hand/wrist before seamlessly transitioning to its position as the "roof" of the carpal tunnel

3. Pisiform, Pisohamate ligament, abductor digiti minimi - ulnar boundary

4. The hook of hamate - radial boundary