Froment's sign is used to test for a compromised adductor pollicis muscle.

In human anatomy, the adductor pollicis muscle is a muscle in the hand that functions to adduct the thumb.

The palmar surface is narrow, rounded, and rough, for the attachment of ligaments and a part of the adductor pollicis muscle.

The severed end of the ligament would become trapped under the aponeurosis of the adductor pollicis muscle and therefore be unable to return to its proper anatomic position.

In most cases of a complete tear, the aponeurosis of the adductor pollicis muscle may be interposed between the bones of the MCP joint and the torn ligament.

In humans, the adductor pollicis muscle (and the adductor hallucis in the foot) is a well-developed remnant of the first contrahens though it has lost the insertion on the distal phalanx of the thumb.

It occurs when the aponeurosis of the adductor pollicis muscle becomes interposed between the ruptured ulnar collateral ligament (UCL) of the thumb and its site of insertion at the base of the proximal phalanx.

The deep palmar arch lies upon the bases of the metacarpal bones and on the interossei of the hand, being covered by the oblique head of the adductor pollicis muscle, the flexor tendons of the fingers, and the lumbricals of the hand.