A study on the accessory head of the flexor pollicis longus muscle (Gantzer's muscle)

Introduction: The present study was planned to analyze the Accessory Head of the Flexor Pollicis Longus muscle' (AHF-PL) or Gantzer's muscle and its incidence. It is an additional muscle in the forearm which might cause pressure symptoms to the underlying structures, especially to the anterior interos-seus nerve. Materials and Methods: This study was performed on 180 upper limbs (90 right and 90 left). The morphology and the morphometry of AHFPL was done. In this investigation, we observed the various shapes, origins, insertions, nerve supplies and relations of the muscle. Observations and Results: The incidence of the accessory head of the fexor pollicis longus muscle was seen in 92 cases (51.11%). It was found bilaterally in 66 (71.73%) cases and unilaterally in 26 cases (28.26%), among which, in 16, it was seen on the right side and in 10 on the left side. With the increasing incidence of the Gantzer's muscle, one can call it as an evolutionary muscle. Conclusion: The present study supplements the knowledge on the morphology of AHFPL muscle and its relationship with the anterior interosseus nerve. An increased incidence of this muscle may be the causative factor for the complete anterior interosseous nerve syndrome.