Microsurgical Anatomy of Hypothenar Flap

Abstract

A microsurgical anatomical study was performed in the hypothenar area in 34 hands of 17 fresh cadavers. The hands were injected by latex through the humeral arteries. The hypothenar area was dissected under a microscope. The length, diameter and location of the branches from the ulnar artery and cutaneous branches from the proper artery of the little fingers were examined. The sources of blood supply to the hypothenar flaps were: (1) one fairly constant hypothenar cutaneous branch of the ulnar artery together with two to six other cutaneous branches from the ulnar artery. The hypothenar cutaneous branch of the ulnar artery had a pedicle of 9.9mm in length, 0.13mm in diameter. This artery originated from the ulnar artery 1.6 cm proximal to the pisiform; (2) four to six cutaneous branches from the proper arteries of the little finger; (3) the cutaneous and muscular branches from the deep branch of the ulnar artery. The venous return was through (1) concomitant veins of the cutaneous branches of the ulnar artery; (2) a palmar subcutaneous venous network. The flap was innervated by one to two branches from the superficial branch of the ulnar nerve. This anatomical study indicates that a flap from the hypothenar area can be harvested with the pedicle of the hypothenar branch of the ulnar artery to repair soft tissue defects in hyopthenar area, palmar wrist region or fingers with the advantage of direct closure of the donor area.