[1] (These are named after the ulna, the long bone on the little finger side of the arm.)

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.

[2][3] It is approximately 4 cm long, beginning proximally at the transverse carpal ligament and ending at the aponeurotic arch of the hypothenar muscles.

[4] The ulnar tunnel is named after the French surgeon Jean Casimir Félix Guyon, who originally described the canal in 1861.

Guyon's canal syndrome[7] may be secondary to ganglion cyst formation, or compression against a bicycle handlebar.