Ulnar Nerve

After the ulnar nerve passes behind the medial epicondyle, it enters the forearm between the two heads of the flexor carpi ulnaris muscle.

The nerve gives branches to the flexor carpi ulnaris and the medial half of the flexor digitorum profundus.

The ulnar nerve then travels along side the ulna bone of the forearm into the wrist.

As the nerve descends into the forearm, it stays medially above the flexor digitorum profundus and under the flexor carpi ulnaris, giving branches to these muscles.

In the lower part of the forearm the ulnar nerve lies lateral to the flexor carpi ulnaris muscle and medial to the ulnar artery.

At the wrist, the ulnar nerve lies just lateral to the pisiform bone.The superficial branch of the ulnar nerve supplies and passes under the palmaris brevis muscle and divides into palmar digital nerves.The deep branch of the ulnar nerve innervates the three hypothenar muscles, the medial two lumbricals, the seven interossei, the adductor pollicis and the deep head of the flexor pollicis brevis. It supplies all intrinsic hand muscles which lie medial to the flexor pollicis longus except the lateral two lumbricals (median n.)

The deep branch of the ulnar nerve innervates:

The ulnar nerve provides palmar and dorsal sensory innervation to the little finger and half of the ring finger.

Pinching of the ulnar nerve often causes paresthesia in the fourth & Fifth digit.

Entrapment or injury of the ulnar nerve below the elbow may result in a claw hand deformity due to the unopposed preserved function of the flexor digitorum profundus.