The ulnar canal or ulnar tunnel (also known as Guyon's canal or tunnel) is a semi-rigid longitudinal canal in the wrist that allows passage of the

ulnar artery The ulnar artery is the main blood vessel, with oxygenated blood, of the medial aspects of the forearm. It arises from the brachial artery and terminates in the superficial palmar arch, which joins with the superficial branch of the radial ar ...

and

ulnar nerve In human anatomy, the ulnar nerve is a nerve that runs near the ulna bone. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest in the human body unprotected by muscle or bone, so injury is ...

into the hand. The roof of the canal is made up of the superficial

palmar carpal ligament The palmar carpal ligament (also volar carpal ligament or ''Guyon's Tunnel'') is the thickened portion of antebrachial fascia on the anterior of the wrist. It is officially unnamed.Moore, Keith L., Arthur F. Dalley II: ''Clinically Oriented Anatom ...

, while the deeper flexor retinaculum and

hypothenar muscles The hypothenar muscles are a group of three muscles of the palm that control the motion of the little finger. The three muscles are: * Abductor digiti minimi * Flexor digiti minimi brevis * Opponens digiti minimi Structure The muscles of hypot ...

comprise the floor. The space is medially bounded by the

pisiform The pisiform bone ( or ), also spelled pisiforme (from the Latin ''pisifomis'', pea-shaped), is a small knobbly, sesamoid bone that is found in the wrist. It forms the ulnar border of the carpal tunnel. Structure The pisiform is a sesamoid bone, ...

and

pisohamate ligament The pisohamate ligament is a ligament in the hand. It connects the pisiform to the hook of the hamate. It is a prolongation of the tendon of the flexor carpi ulnaris. It serves as part of the origin for the abductor digiti minimi. It also forms t ...

more proximally, and laterally bounded by the

hook of the hamate The hamate bone (from Latin hamatus, "hooked"), or unciform bone (from Latin ''uncus'', "hook"), Latin os hamatum and occasionally abbreviated as just hamatum, is a bone in the human wrist readily distinguishable by its wedge shape and a hook-l ...

more distally. It is approximately 4 cm long, beginning proximally at the transverse carpal ligament and ending at the aponeurotic arch of the hypothenar muscles.

Eponym

The ulnar tunnel is eponymously named after the French surgeon

Jean Casimir Félix Guyon Jean Casimir Félix Guyon (21 July 1831 – 2 August 1920) was a French surgeon and urologist born in Saint-Denis, Ile-Bourbon ( Réunion). He studied medicine in Paris, receiving his doctorate in 1858. He was appointed ''médecin des hôpitau ...

, who originally described the canal in 1861.

Clinical significance

Entrapment of the ulnar nerve at the ulnar canal can result in symptoms of ulnar neuropathy, including numbness or weakness of certain parts of the hand. (''See full article on

ulnar nerve entrapment Ulnar nerve entrapment is a condition where the ulnar nerve becomes physically trapped or pinched, resulting in pain, numbness, or weakness, primarily affecting the little finger and ring finger of the hand. Entrapment may occur at any point from ...

.)'' This is known as ulnar nerve entrapment or Guyon's canal syndrome. There are four subtypes of

ulnar neuropathy Ulnar neuropathy is a disorder involving the ulnar nerve. Ulnar neuropathy may be caused by entrapment of the ulnar nerve with resultant numbness and tingling. It may also cause weakness or and paralysis of the muscles supplied by the nerve. Si ...

at the wrist, of which type II is the most common. Guyon's canal syndrome may be secondary to

ganglion cyst A ganglion cyst is a fluid-filled bump associated with a joint or tendon sheath. It most often occurs at the back of the wrist, followed by the front of the wrist. Onset is often over several months, typically with no further symptoms. Occasional ...

formation, or compression against a

bicycle handlebar A bicycle handlebar is the steering control for bicycles. It is the equivalent of a tiller for vehicles and vessels, as it is most often directly mechanically linked to a pivoting front wheel via a stem which in turn attaches it to the fork. B ...

References

{{Authority control Wrist

Eponym

Clinical significance

See also

References