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.
Learning this group? Read How to learn the brachial plexus.
Reference facts
- Roots
- C8, T1 (medial cord), with a variable C7 contribution
- 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).
Frequently asked questions
What are the roots of the ulnar nerve?
The ulnar nerve arises from C8, T1 (medial cord), with a variable C7 contribution.
What muscles does the ulnar nerve supply?
The ulnar nerve supplies the flexor carpi ulnaris, medial half of flexor digitorum profundus, and most intrinsic hand muscles (hypothenar, interossei, medial two lumbricals, adductor pollicis).
What is the sensory distribution of the ulnar nerve?
The ulnar nerve carries sensation from the medial 1½ digits and the medial palm and dorsum of the hand.
What is the course of the ulnar nerve?
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).