Ulnar Nerve in Guyon's Canal

  • In Section 8 the ulnar nerve is located in Guyon’s Canal with the ulnar artery.
  • The ulnar nerve is positioned volar and superficial to the ulnar artery in Guyon’s Canal dorsal to the pisohamate ligament.
  • Proximally the ulnar nerve is radial to the pisiform and FCU tendon muscle.
  • The common terminal branches of the ulnar nerve are the deep motor branch to the adductor pollicis and deep head of the flexor pollicis brevis muscles, motor branch to the hypothenar muscles and the ulnar two lumbricals, the ulnar digital sensory nerve to the little finger, and the common digital sensory nerve in the ring/little web space.
Diagrams & Photos
  • Ulnar nerve with its sensory and motor branches.
    Ulnar nerve with its sensory and motor branches.
  • Guyon's Canal located ulnar to the carpal tunnel. Note ulnar cut edge of the transverse carpal ligament and median nerve in carpal open carpal tunnel.
    Guyon's Canal located ulnar to the carpal tunnel. Note ulnar cut edge of the transverse carpal ligament and median nerve in carpal open carpal tunnel.
  • Opening pisohamate ligament of Guyon's canal.
    Opening pisohamate ligament of Guyon's canal.
  • Ulnar nerve and artery in Guyon's canal. Yellow arrow on cut edge of pisohamate ligament and ulnar edge of the transverse carpal ligament.
    Ulnar nerve and artery in Guyon's canal. Yellow arrow on cut edge of pisohamate ligament and ulnar edge of the transverse carpal ligament.
  • Motor branch of ulnar nerve
    Deep motor branch of ulnar nerve. Note cut FDS tendons folded out of the carpal tunnel.
  • Motor branch of ulnar nerve to hypothenar muscles (yellow arrow).
    Motor branch of ulnar nerve to hypothenar muscles (yellow arrow).
  • Nerve with axons enclosed in endoneurium (1); Fascicle enclosed in perineurium (2); Fascicular groups enclosed in connective tissue called internal epineurium (3); Internal epineurium (4); External epineurium (5); Epineural blood vessels (6).
    Nerve with axons enclosed in endoneurium (1); Fascicle enclosed in perineurium (2); Fascicular groups enclosed in connective tissue called internal epineurium (3); Internal epineurium (4); External epineurium (5); Epineural blood vessels (6).
Key Points
  • The ulnar nerve originates from the medial cord of the brachial plexus, specifically from the C8-T1 nerve roots.
  • The ulnar nerve also provides motor innervation to the ulnar innervated intrinsic muscles which include the hypothenar muscles, the dorsal and volar interosseous muscles, the ulnar two lumbrical muscles, the adductor pollicis, and the deep head of the flexor pollicis brevis are all innervated by the ulnar nerve.
  • The proximal third of Guyon’s Canal contains motor and sensory components of the ulnar nerve so compressing lesions can affect motor and sensory function, the middle third motor and sensory separate and lesions compressing the nerve typically affect the motor branch, and in the distal third only sensory parts are at risk for compression.
  • Potential compressive lesions include ganglions, lipoma, hemangiomas, ulnar artery thrombosis or ulnar artery aneurysms.
Anatomy References
Anatomic Abbreviations
Hand Surgery Resource Anatomy Diagnostic Guide (Chapter)