Little finger

Recommended video: Regions of the upper limb [17:55]

Regions of the upper limb seen from the anterior and posterior views.

The little finger, also known as the pinky, is the fifth digit of the human hand. It is the most ulnar and smallest of all fingers and is located next to the ring finger (fourth digit).

Similar to the other fingers, with the exception of the thumb, the bony framework of the little finger is composed of three phalanges: the proximal, middle and distal phalanges.

The base of the proximal phalanx of the little finger forms an articulation with the head of the fifth metacarpal at the metacarpophalangeal (MCP) joint. The head of the proximal phalanx articulates with the base of the middle phalanx to form the proximal interphalangeal (PIP) joint. Lastly, the articulation of the head of the middle phalanx with the base of the distal phalanx of the little finger form the distal interphalangeal (DIP) joint. In addition, the distal phalanx provides bony support to the fingernail and tissue surrounding the little finger.

In contrast to the muscly thenar eminence, the less prominent hypothenar eminence is found on the ulnar side of the palm and is formed by the muscles of the little finger. These include the abductor digiti minimi, flexor digiti minimi, and opponens digiti minimi muscles. The palmaris brevis is also located in this region, however is not considered a hypothenar muscle, but is typically classified on it's own as an outstanding superficial muscle of this region.

The hypothenar muscles span between the medial aspect of the carpus to the carpal and metacarpal bones of the little finger. Blood supply is provided by the ulnar artery via the superficial palmar arch, while the skin overlying the little finger and ulnar side of the ring finger is supplied by the ulnar nerve (C8, T1).