Master Nerve Palsies - Trouble Making Fist with Picmonic for Medicine

The proximal ulnar nerve is comprised of the C8 and T1 nerve roots and carries both sensory and motor fibers. This nerve originates from the brachial plexus at the axilla and travels along the medial aspect of the upper limb, passing the medial epicondyle of the humerus. It innervates the flexor carpi ulnaris and the medial half of the flexor digitorum profundus. From there, it continues down the medial forearm to innervate the flexors of digits 4 and 5. Additionally, the ulnar nerve innervates the intrinsic muscles of the hand.

The proximal ulnar nerve runs through the retrocondylar groove at the elbow, which is positioned posterior and medial to the medial epicondyle. A fracture in this region may damage it.

The proximal ulnar nerve innervates the medial half of flexor digitorum profundus, which facilitates flexion of digits 4 and 5. When making a fist with a proximal ulnar nerve injury, digits 4 and 5 are unable to flex and face unopposed extension by extensor digitorum. This hand position resembles an “OK” sign.

The proximal ulnar nerve innervates the medial half of the flexor digitorum profundus, which facilitates the flexion of digits 4 and 5. When making a fist with a proximal ulnar nerve injury, digits 4 and 5 are unable to flex and face unopposed extension by the extensor digitorum. This hand position resembles an “OK” sign.

Without innervation from the ulnar nerve, muscle wasting of the opponens digiti minimi, abductor digiti minimi, and flexor digiti minimi brevis may occur.