Palmaris brevis

The palmaris brevis is a small, thin, quadrangular intrinsic muscle of the hand. It is positioned directly beneath the skin on the ulnar side of the palm. This muscle does not act directly on the little finger; therefore, it is not classified as the muscle of the little finger. It wrinkles the skin on the ulnar side of the palm and improves grip by tightening the palmar aponeurosis.