Ulnar canal

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 and ulnar nerve into the hand. The roof of the canal is made up of the superficial palmar carpal ligament, while the deeper flexor retinaculum and hypothenar muscles comprise the floor. The space is medially bounded by the pisiform and pisohamate ligament on the ulnar side, and the hook of the hamate on the radial side. It is approximately 4 cm long, beginning proximally at the transverse carpal ligament and ending at the aponeurotic arch of the hypothenar muscles.