From	C8, T1 (branch from Medial cord)
Innervates	flexor carpi ulnaris flexor digitorum profundis lumbrical muscles opponens digiti minimi flexor digiti minimi abductor digiti minimi interossei adductor pollicis

1. Froments Sign:

Image link.

Flexion of IP 1 with hyperextension of MCP 1 – (pathological hand on the left)

Flexion occurs in the IP joint of the thumb rather than adduction (as would occur with correct use of the adductor pollicis).

So flexion of the IP thumb joint accompanied by extension of MCP 1= Ulna nerve pathology.

2. The picture shows a very distal Ulnar Nerve outlet. Compression in this area can cause ‘Guyons Canal Syndrome’ or ‘Handlebar Palsy’.

Structure: Between the Pisiform and Hamate carpals is a ligament (pisohamate lig.). It forms a fibrous tunnel which the ulnar nerve and artery travel through.

> What causes this problem?

Heavy gripping activities.
Repeated wrist and hand motions.
Constant pressure on the palm of the hand.

This is common in cyclists and weight lifters from the pressure of gripping. It can also happen after running a jackhammer… or when a patient is using crutches.

3. A hand in ulnar claw position will have the 4th and 5th fingers drawn towards the back of the hand at the first knuckle and curled towards the palm at the second and third knuckles.

 

Some sources incorrectly refer to the ulnar claw as a “hand of benediction” or “pope’s blessing”. However, the term “hand of benediction” or “pope’s blessing” more commonly refers to a similar hand position which is caused by damage to the median nerve and is only present when the patient is asked to make a fist.

The hand will show hyper-extension of the metacarpophalangeal joints (MCP) (due to paralysis for flexor lumbricals) and flexion of the distal and proximal Interphalangeal (IP) joints of the 4th and 5th digits (ring and little finger) (The lumbricals and interossei also extend the IP joints of the fingers by insertion into the extensor hood; their paralysis results in weakened extension).

The clawing will become most obvious when the person is asked to flex the digits from an extended position as the 4th and 5th digits can not flex due to the injury to the ulnar nerve. 1st, 2nd and 3rd digits will partially flex giving them a “claw-like” appearance, this happens because the Thenar muscles (Abductor pollicis brevis, Flexor Pollicis brevis and Opponens pollicis) are innervated by the median nerve as the first two lumbricals of digit 2 and 3 are.