Ulnar artery thrombosis associated with anomalous hypothenar muscle.

Ulnar artery thrombosis should be considered in patients presenting with cold intolerance or ischemia of the small and ring fingers, or a mass in the hypothenar area. Frequently this diagnosis is associated with a history of repetitive blunt trauma to the ulnar hand, thereby traumatizing the ulnar artery in Guyon's canal. This report presents a case of ulnar artery thrombosis associated with an abnormal muscle originating on the palmar antebrachial fascia, traversing volar to the ulnar artery and nerve, and inserting on the ulnar border of the abductor digiti minimi. This muscle is an abductor digiti minimi accessorius.