Case Report International Journal of Anatomical Variations (2014) 7: 100–102 eISSN 1308-4038 Gantzer of flexor pollicis longus – a culprit in Kiloh-Nevin syndrome Introduction Muscle anatomic variants are commonly encountered as serendipitous findings during surgery or routine dissections in medical schools. These variants may consist of absence of a muscle, supernumerary muscles, deviation from the normal course, or an unusual origin or insertion. While most such findings help adding to a compendium of variations for future academic dialogue, a mass effect of these variants may present as palpable swellings, frank compressive syndromes or at worst, veiled unexplained pain nagging the clinician and the patient and therefore their awareness has far reaching consequences. Case Report During routine dissection for the first year medical students at the Amrita School of Medicine, a well-developed accessory belly of the flexor pollicis longus (FPL-Ah) was noted under the flexor digitorum superficialis on the anterior aspect of the right forearm of a 64-year-old male cadaver. Its proximal attachment was on the medial epicondyle, it coursed downwards and laterally to get attached to the beginning of the FPL tendon on its medial aspect (Figure 1). It was supplied by the anterior interosseous nerve, which was seen posterior to the FPL-Ah. The median nerve was coursing in front of the FPL-Ah (Figure 2). Discussion FPL, one of the three deep flexor muscles of the forearm takes its origin from the anterior surface of the shaft of the radius and the adjacent interosseous membrane and is inserted into the base of the distal phalanx of the thumb [1]. Gantzer muscle is defined as an accessory muscle head connecting the superficial and deep flexors. This additional Rathi SUDHAKARAN Asha Joselet MATHEW Department of Anatomy, Amrita School of Medicine, AIMS, Kochi-41, Kerala, INDIA. Dr. Rathi Sudhakaran, MD Professor Department of Anatomy Amrita School of Medicine Amrita Institute of Medical Sciences and Research Centre Amrita Vishwa Vidyapeetham Ponekkara P.O., Kochi- 41 Kerala, INDIA. +91 (484) 2345774 rathis@aims.amrita.edu Received August 31st, 2013; accepted April 17th, 2014 Abstract In a routine dissection conducted in the Department of Anatomy, Amrita School of Medicine, Kochi, a well-developed variant belly of the flexor pollicis longus muscle was noted. © Int J Anat Var (IJAV). 2014; 7: 100–102. Key words [Gantzer’s muscle] [flexor pollicis longus] [rupture] [compressive neuropathy] [anterior interosseous nerve] Published online July 31st, 2014 © http://www.ijav.org Figure 1. Photograph showing the origin of accessory belly of the flexor pollicis longus (FPL-Ah) and tendon of flexor pollicis longus (FPL) in the right forearm. FPL FPL-Ah