Abductor Digiti Minimi Under the Skin, Palmar View

Description

Palmar skin has been removed to expose the abductor digiti minimi along the ulnar border of the hand, forming the most superficial contour of the hypothenar eminence as it runs from the pisiform region toward the base of the proximal phalanx of the little finger. Radial to it, the thenar eminence and central palmar compartment frame the metacarpals and phalanges in anatomical position, while the carpal bones sit proximally at the wrist in two rows. Proximal ulnarly, the flexor carpi ulnaris tendon approaches the pisiform, with its continuation via the pisohamate and pisometacarpal ligaments toward the hook of hamate and the fifth metacarpal. Joint capsules are indicated at the metacarpophalangeal and interphalangeal articulations. Clean landmarks. Functionally, the abductor digiti minimi is a reliable surface and surgical landmark for the ulnar side of the palm because its proximal attachment near the pisiform lies adjacent to Guyon’s canal, where the ulnar nerve and ulnar artery enter the hand superficial to the flexor retinaculum. Denervation from ulnar tunnel syndrome (cyclist’s palsy) or iatrogenic injury during ulnar-sided wrist approaches can produce wasting of the hypothenar eminence and weakness of little-finger abduction, often paired with sensory changes in the ulnar one and a half digits. Seeing the muscle in relation to the carpal arch clarifies why symptoms may spare dorsal ulnar hand sensation when the lesion is distal to the dorsal cutaneous branch. Hand anatomy courses and surface anatomy teaching benefit from this palmar dissection-style view when introducing hypothenar compartment organization, tendon insertions, and the bony landmarks of pisiform and hamate. It also fits operative atlases and clinical hand therapy materials illustrating ulnar neuropathy patterns, hypothenar atrophy, and reconstructive planning around the fifth ray. Anatomical accuracy verified by SciePro's Medical Advisory Board.