RESUMEN
Gantzer muscles are variant muscles in the anterior forearm inserting into the flexor pollicis longus or, less often, the flexor digitorum profundus. The presence of Gantzer muscles can cause a compressive neuropathy affecting the anterior interosseous nerve (Kiloh-Nevin syndrome). These muscles must also be considered when anterior forearm fasciotomies are performed for the management of acute compartment syndrome. In this case report, a novel Gantzer muscle originated from the flexor digitorum superficialis as well as the investing fascia of the brachialis muscle; the latter site is a novel proximal attachment not previously reported. In addition, the Gantzer muscle possessed rare characteristics because it (1) possessed a split tendinous distal insertion into both the flexor pollicis longus and flexor digitorum profundus, (2) exhibited a triangular morphology, and (3) was innervated by the median nerve. Most importantly, the dual origin of this Gantzer muscle formed a tunnel containing branches of the median nerve; therefore, this report documents a unique anatomical scenario in which the Gantzer muscle may compress and cause entrapment of aspects of the median nerve.
