Ulnar nerve

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(Redirected from Funny bone)

Template:Infobox Nerve Image:Gray816.png The ulnar nerve is a nerve that in humans runs down the arm and forearm, and into the hand.

The ulnar nerve comes from the lower cord of the brachial plexus, and runs posterior to the humerus down the arm, going behind the medial epicondyle at the elbow. This part of the ulnar nerve is known as the funnybone for two reasons: because of its proximity to the humerus (and the similar word "humorous"), and because of the mild pain and tingling throughout the forearm associated with sudden compression of the nerve at this point (the label 'funnybone' is thus ironic, since this feeling isn't funny at all).

It enters the anterior (front) side of the forearm, and runs alongside the ulna. It supplies one and a half muscles in the forearm: flexor carpi ulnaris (which flexes and adducts the wrist), and the medial two digits of flexor digitorum profundis (a muscle that flexes the fingers).

After its journey down the ulna, the ulnar nerve enters the palm of the hand (passing above the flexor retinaculum), to supply most of the intrinsic muscles of the hand. Muscles in the hand supplied by the ulnar nerve include the medial two lumbrical muscles, the muscles of the hypothenar eminence (opponens digiti minimi, flexor digiti minimi and abductor digiti minimi), the interossei (palmar and dorsal groups) and the adductor pollicis muscle. It does not supply the thenar muscles (flexor pollicis brevis, abductor pollicis brevis and opponens pollicis brevis) and the lateral two lumbrical muscles.

Sensory information from the medial one and a half fingers, (the little finger and half of the ring finger,) and the body of the hand below these fingers, on both the palmar and dorsal surfaces of the hand, is sent back to the brain via the ulnar nerve.

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