Ulnar nerve
Branches · C8 T1
Passes behind the medial epicondyle in the cubital tunnel — where it is palpable and vulnerable — and enters the hand through Guyon's canal.
Traced from the start
Detail
- Motor
- Flexor carpi ulnaris and the medial half of flexor digitorum profundus. All the intrinsic hand muscles except LOAF — the interossei, the medial two lumbricals, adductor pollicis and the hypothenar group
- Sensory
- The medial one and a half digits, on both the palmar and the dorsal surface
When it goes wrong
Fracture of the medial epicondyle, or compression in the cubital tunnel
Weak grip with sensory loss along the medial border. Clawing is mild here — the ulnar paradox: the higher lesion also denervates flexor digitorum profundus, so the fingers cannot flex into a claw.
Compression at Guyon's canal at the wrist
Marked clawing of the ring and little fingers — hyperextended at the metacarpophalangeal joints, flexed at the interphalangeal joints, and present at rest. Do not confuse it with the median hand of benediction, which is absent at rest and appears only on trying to make a fist. Froment sign is positive as adductor pollicis fails and flexor pollicis longus substitutes.
Practise this structure
1 question in the bank tagged Ulnar Nerve.