Original Article ID: JCDR/2012/4144:2114 A Study of the Accessory Muscles in the Flexor Compartment of the Forearm Anatomy Section UMAPATHY SEMBIAN, SRIMATHI T., MUHIL M., NALINA KUMARI S.D., THIRUMALAIKOLUNDU SUBRAMANIAN ABSTRACT surgical scars, and congenital deformities and partially amput­ Aim: To ascertain the prevalence of the accessory muscles in ated limbs were excluded from our study. the flexor (anterior) compartment of the forearm. Methods: During the routine undergraduate dissection, we A wide array of the supernumerary muscles has been described studied the muscular pattern in all the upper limbs. in the anatomical, surgical and radiological literatures. After making an incision in the skin, the superficial fascia and In a vast majority of the cases, the accessory muscles are asympt­ the deep fascia were reflected, thus exposing the flexor muscle omatic and they represent incidental findings at surgery or imaging. compartment. A thorough investigation was carried out to verify all the two layers of muscles, both the superficial layer and the Hence, this study was taken up to access the occurrence of the deep layer. accessory muscles in the flexor compartment of the forearm. The investigation included the questions (a) whether the muscles Materials and Methods: This descriptive study was conducted for that compartment were present or not (absence), and if in the Department of Anatomy, Chennai Medical College Hospital present its both proximal and distal attachments, (b) if there is any and Research Centre, Trichy and in the Sri Ramachandra acessory muscles present, its attachments. University, Chennai, India. Results: In our study, we found that only in two different limbs, This study was conducted from 2006 to 2012 for a period of unilaterally, there was a presence of (a) an Additional Head of seven years in the Department of Anatomy. the Flexor Pollicis Longus (AHFPL­Gantzer’s muscle) and in a During the routine cadaveric dissection for undergraduate another limb (b) an Accessory Palmaris Longus was found and teaching in one hundred cadavers for a period of seven years, both belonged to the male sex. we studied the presence of abnormal variations in the muscular Conclusion: Only 2% of the limbs in our study exhibited an pattern of the anterior compartment of the forearm. abnormal pattern of the muscles. All the upper limbs were dis­articulated and were tagged for This study will supplement our knowledge on the possible their respective sexes and numbers. variations of the muscles in this region, which would be useful Among the 100 cadavers, 90 belonged to the male sex, whereas for hand surgeons, orthopaedic surgeons, general surgeons, 10 belonged to the female sex. In a total of 200 upper limbs: 100 physicians and plastic surgeons, as it would probably compress limbs to the right side and 100 limbs to the left side. the neuro­ vascular bundle because of its close relationship, Upper limbs which exhibited fractures both pre mortem as leading to both vascular and neural symptoms. well post mortem, those with an obscuring pathology, previous Key Words: Gantzer’s muscle (AHFPL), Carpel tunnel syndrome, Accessory Palmaris Longus, Guyon’s canal INTRODUCTION are noted and the occurrence of an additional muscle is very A wide array of supernumerary and accessory musculature has uncommon. been described in the anatomical, surgical and radiological In case of the Carpel Tunnel Syndrome, it is said to be because of literatures. In most of the cases, the accessory muscles are the inflammation with subsequent oedema, which leads to com- asymptomatic and they are found incidentally during surgery or pression in the carpel tunnel, but in certain cases, these accessory imaging. However, in some cases, the accessory muscles may muscles can also produce the Carpel Tunnel Syndrome due to produce clinical symptoms due to the compression of the neuro overcrowding in the fibro osseus tunnels. vascular structures, especially in the fibro osseus tunnels. Hence, this study was taken to rule out the prevalence of the In some cases, if an obvious cause of the neurological symptoms muscles which are encountered in our population. is not evident, the recognition and the careful evaluation of the accessory muscles may aid in the diagnosis and treatment of these AIM cases. The aim of this study was to ascertain the prevalence of the Variations in the extensor compartment of the forearm are quite accessory muscles in the flexor compartment of forearm to help common. However, in the flexor compartment, not many variations the physicians, the general surgeons and the hand surgeons, to 564 Journal of Clinical and Diagnostic Research. 2012 May (Suppl-2), Vol-6(4): 564-567 www.jcdr.net Umapathy Sembian et al., A Study of the Accessory Muscles in the Flexor Compartment of the Forearm keep this in mind for the diagnosis as well as for the treatment of If any abnormality was found in the muscular pattern, it was such conditions, which involves compression of the neuro vascular recorded in detail and photographed. structures. OBSERVATION MATERIALS AND METHODS In our study, we came across two variations of accessory muscles The present study was conducted in the Department of Anatomy, in two different limbs unilaterally, which belonged to the male sex. Chennai Medical College Hospital and Research Centre, Trichy (a) AHFPL-Additional Head of the Flexor Pollicis Longus and in the Department of Anatomy, Sri Ramachandra University, (GANTZER’S muscle) on the left side forearm, (unilateral) of a Chennai, India. male cadaver. This study was done from 2006-2012, for a total of seven years, (b) An Accessory Palmaris longus on the right side forearm and it consisted of 100 cadavers which were used for the routine (unilateral) of a male cadaver. undergraduate teaching program. The GANTZER’S muscle ( AHFPL) originated from the undersurface All the cadavers belonged to the adult category and they were of the Flexor Digitorum Superficialis muscle, just distal to its origin without any obvious pathological deformities. The cadavers were from the medial epicondyle. On further dissection, the accessory preserved by the injection of formalin based preservative (10% belly was found to run downwards to the medial aspect of the formalin) and they were stored in tanks. Before taking photographs, Flexor Poliicis Longus tendon proper for its insertion at the junction the dissected region was rinsed with water. between the proximal and the middle thirds of the forearm. From all the cadavers, the upper limbs on both the sides were dis- The accessory Palmaris Longus originated from different areas, articulated after the dissection, with the subsequent tagging of sex namely few fibers from the deep fascia of the forearm, passing and the identification number for that particular cadaver from which through the GUYON’S canal over the ulnar vessels and the nerves the limb was disarticulated. and merging with the hypothenar muscles, few fibres from the Both the sexes were included in our study. There were 90 male tendon of the Palmaris Longus proper and at last, few fibres from cadavers and 10 female cadavers. The disarticulated limbs were in the flexor retinaculum. a total of 200 (100-right side and 100-left side). The tendon of the accessory Palmaris longus muscle got inserted Meticulous care was taken to exclude the limbs which exhibited into the medial epicondyle. obscuring pathologies, fractures (both pre- and post-mortem), de- formities, congenital anomalies and previous surgery in this region DISCUSSION and amputations. In the forearm, the muscles can be classified into a superficial set of muscles and a deep set of muscles. METHODS The superficial set of the muscles are the Pronator teres (PT), the The dissections were carried out in all the limbs on the right and left Flexor carpi radialis (FCR), the Palmaris longus (PL), the Flexor sides as per the instructions which were given by Cunningham’s digitorum superficialis (FDS) and the Flexor carpi ulnaris (FCU). The Manual of Practical Anatomy. deep set of the muscles are the Flexor digitorum profundus(FDP), The skin was reflected to expose the superficial fascia, and it was the Flexor pollicis longus(FPL) and the Pronator quadrates(PQ). examined for its contents: cutaneous nerves and vessels and if The Flexor pollicis longus is one of the deep flexors of the forearm any abnormality was noted, it was recorded in detail. Then the and it originates from the grooved anterior surface of the radius superficial fascia was incised and it was reflected to expose the and from the adjacent interosseous membrane and gets inserted deep fascia. Then the deep fascia was incised and it was reflected into the base of the distal phalanx of thumb [1]. to expose the muscles of the superficial compartment of the fore arm. It has been noted that it can arise from the lateral border of the All the muscles were examined for their presence, position, and Gantzer’s muscle (AHFPL), Carpel tunnel syndrome, Accessory Palmaris Longus, Guyon’s canal cor onoid process or from the medial epicondyle of the humerus. Key Words: their attachments, and then the superficial compartment was cut This variable slip of the muscle is called as the GANTZER’S to expose the deep compartment muscles; again, the routine muscle [2]. investigation was carried out. [Table/Fig-1,2,3]: AHFPL (Gantzer’s muscle) Journal of Clinical and Diagnostic Research.2012 May (Suppl-2), Vol-6(4): 564-567 565 Umapathy Sembian et al., A Study of the Accessory Muscles in the Flexor Compartment of the Forearm www.jcdr.net [Table/Fig-4,5,6]: ACCESSORY Palmaris longus The prevalence of the Gantzer’s muscle has been noted to be We would like to conclude that the chances for AIN to get entrapped around 50-60% by Al-Quattan [3],and Oh [4].