The abductor digiti minimi muscle is a particularly strong skeletal muscle of the hand. It is attached to the bones of the hand by tendons and is shaped like a spindle. The muscle runs from the pisiform bone, which is in the wrist, to the joint of the first knuckle. It also connects to the second joint of the little finger.  Its main function is to pull the little finger away from the other fingers (abduction). It also plays an important role when the hand grasps something tightly. It helps flex the joint of the first knuckle. Nerve functions are supplied by the deep branch of the ulnar nerve. The abductor digiti minimi muscle can be used as a donor muscle in opponensplasty, a surgery to restore thumb opposition that has been damaged or injured. Anatomy textbooks report nine variations of the structure and tendon attachments to the bone that are common enough to be medically reported in the literature.