Bitendinous Palmaris Longus Associated With Double-Headed Accessory Abductor Digiti Minimi: A Case Report

The palmaris longus (PL) is one of the most variable muscles in the human body, frequently exhibiting morphological variants or congenital agenesis. Variations in the abductor digiti minimi and vascular anomalies such as a superficial ulnar artery can also occur, but their coexistence is exceptionally rare. During the routine dissection of an adult male cadaver, an unusual triad of anatomical variations was observed in the right forearm and hand. A bitendinous PL was present, composed of proximal and distal tendinous segments with a central muscle belly. A double-headed accessory abductor digiti minimi was also identified, with the lateral head arising from the distal tendon of the PL and the medial head from the pisiform, with the lateral head traversing Guyon's canal over the ulnar nerve and artery before uniting with the medial head. In addition, a superficial ulnar artery was observed, originating from the distal brachial artery at mid-arm level, coursing superficially over the PL tendon. A well-developed palmaris brevis, occurring as several distinct bundles, was also noted. On the contralateral side, a bifid PL tendon was noted without an associated accessory abductor digiti minimi variation. A comprehensive appreciation of its anatomical subtleties holds significance not merely in the academic realm but also as a matter of practical importance in both diagnostic evaluation and therapeutic intervention.