Nerve
Ulnar nerve
The 'funny bone' nerve
High-yield
Passes behind the medial epicondyle ('funny bone'); injury → claw hand (worse with distal lesions) and Froment sign.
Overview
A terminal branch of the medial cord that runs behind the medial epicondyle and supplies most intrinsic hand muscles, giving fine motor control.
Reference facts
- Roots
C8, T1 (medial cord)
- Course
Descends medially in the arm, passes posterior to the medial epicondyle, between the heads of flexor carpi ulnaris, and enters the hand superficial to the flexor retinaculum (Guyon's canal)
- Motor
Flexor carpi ulnaris, medial half of flexor digitorum profundus, and most intrinsic hand muscles (hypothenar, interossei, medial two lumbricals, adductor pollicis)
- Sensory
Medial 1½ digits and the medial palm and dorsum of the hand
Clinical correlation
Ulnar 'claw hand' is more pronounced with wrist-level lesions (ulnar paradox).