Anomalous hand muscle found in the Guyon's canal at exploration for ulnar artery thrombosis. A case report.

A diagnosis of ulnar artery thrombosis should be considered when a patient reports symptoms of ulnar neuropathy, ischemia in the hand, or a mass in the hypothenar area. A history of repetitive blunt trauma to the hypothenar area is particularly suggestive of this. Ulnar artery thrombosis is possibly associated with an anomalous muscle in the Guyon's canal. The anomalous muscle in this case originated on the flexor carpi ulnaris muscle, was ulnarly innervated, and joined the flexor digiti minimi muscle distally. This patient had a history of blunt injury and a significant smoking history, thus, a causal relationship between the anomalous muscle and ulnar artery thrombosis cannot be stated with certainty.