Ulnar nerve
Nervus ulnaris
NervousNervesArmLeft and right
View left in 3D View right in 3D
- What it is
- The main continuation of the medial cord. It runs down the medial arm, passes behind the medial epicondyle of the humerus (the "funny bone"), enters the forearm through flexor carpi ulnaris, runs under that muscle to the wrist and enters the hand through Guyon's canal beside the pisiform bone.
- Function
- Motor to flexor carpi ulnaris, the medial half of flexor digitorum profundus and most small muscles of the hand (interossei, hypothenar muscles, medial lumbricals, adductor pollicis); sensation from the little finger and half of the ring finger.
- Size
- About 4 mm thick; ~65 cm from the axilla to the little finger
- Clinical note
- Knocking the funny bone jolts this nerve against the epicondyle. Chronic compression at the elbow (cubital tunnel) or wrist gives tingling in the little finger, a weak pinch (Froment sign) and eventually a claw hand.