Abstract: Objective     To provide the clinical anatomical basis for repairing the palm skin defect with the hypothenar skin flap of the descending branches of supracarpal cutaneous branch of the ulnar artery. Methods    From May, 2018 to May, 2019, a total of 42 side upper extremities were used in the research. Twenty-eight side through brachial artery were perfused with red latex for anatomy, 14 side through brachial artery were perfused with ABS and eroded to be vascular cast mold. The branch, course, distribution, communication, outer diameter and anastomosis of the descending supracarpal cutaneous branch of the ulnar artery were anatomically observed and measured.    Results    A line from lentiform bone to the ring, webbing of the little finger was drawn and the line was divided into 3 equal sections. The descending branches of supracarpal cutaneous branch of the ulnar artery arised 14.5 branches, including 6.8 cutaneous branches and 7.7 communicating branches in the distal, middle and proximal 1/3 segments. The cutaneous branches anastomosed with each other to form 1-2 grade cutaneous branch chain in the superficial fascia of hypothenar. The length of cutaneous branches was (1.80±0.60) cm and the diameter of cutaneous branches was (0.23±0.10) mm. The communicating branches was anastomosis with deep branch of ulnar artery, the ulnar margin of superficial palmar arch, the common palmar digital artery or ulnar volar artery of little finger, respectively. The length of communicating branches was (1.60±0.50) cm and the diameter was (0.16±0.06) mm. There was one or two large communicating branches in the proximal and distal 1/3 segments, which can be used as an ideal flap vascular pedicle.   Conclusions     The hypothenar flap is an ideal selection to repair the small tissue defect of palm skin, for it has a constant position of the descending supracarpal cutaneous branch of the ulnar artery in the hypothenar skin flap, with abundant endothelium branch chains, and its skin structure is the homology with the center of the palm.

Key words: Descending branches of supra carpal cutaneous of ulnar artery,  ,  , Hypothenar skin flap, Palm skin repair,  ,  ,  , Clinical anatomy