Accessory Abductor Digiti Minimi Muscle: A Potential Cause of Ulnar Neuropathy at Wrist

Ulnar nerve compression at wrist is manifested either pathologically due to ganglia or neoplasms, or anatomically by the presence of accessory muscles in the hypothenar region. Accessory abductor digiti minimi muscle is an additional muscle encountered rarely in the wrist; presence of which causes high risk of ulnar neuropathy. We report here a case of unilateral accessory abductor digiti minimi muscle on the right hand of an elderly male cadaver of South Indian origin. The accessory muscle had flattened origin from the distal end of deep fascia of the forearm. It then formed a rounded belly and became narrowed to pass through the Guyon’s canal to get attached into radial side of the abductor digiti minimi muscle. Knowledge of existence of additional muscles in the wrist is important for the surgeons as these often cause neuropathy and vascular thrombosis, which greatly affects the movement of the wrist.