Master Nerve Palsies - OK Gesture with Picmonic for Medicine

Comprised of C8 and T1 nerve roots, it originates in the brachial plexus at the axilla, and it courses along the medial aspect of the upper limb and past the medial epicondyle of the humerus. It innervates flexor carpi ulnaris and the medial half of flexor digitorum profundus. From there it courses down the medial forearm to innervate the flexors of digits 4 and 5.

The proximal ulnar nerve courses across the medial epicondyle of the humerus and may be damaged with a fracture to this region.

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 flexion by extensor digitorum. This hand position resembles an “OK” sign.

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 flexion by extensor digitorum. This hand position resembles an “OK” sign.

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 flexion by 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.