An unusual variation - Unilateral Gantzer's muscle

Abstract

The accessory head of flexor pollicis longus (FPL) muscle, also known as the Gantzer's muscle, was first described in 1813. The accessory head of FPL muscle significantly varies between studies in its origin, innervation, and relationships to the anterior interosseous nerve and the median nerve. In a 50-year-old male cadaver, we found an additional muscle belly arising from medial epicondyle and joining with the tendon of FPL muscle. The total length of the accessory muscle was 8 cm and was innervated by the ulnar nerve, which is not mentioned in any of the articles in the literature. It is called as Gantzer's muscle as it is taking origin from medial epicondyle. Due to the significant variations in the origin, insertion, innervation, and relationship to the anterior introsseous nerve, median nerve, ulnar nerve, and ulnar vessels of the accessory head of FPL, dependable anatomical knowledge is essential for diagnosis and treatment of nerve entrapment syndromes and avoiding injury during the surgical procedures.