A STUDY OF UPPER LIMB MUSCLE ANOMALIES AND THEIR EFFECTS ON THE NEUROVASCULAR STRUCTURES P.S.Chitra * 1 , S.Kalaiyarasi 2 . *1 Associate Professor, Department of Anatomy, KAPV Government Medical College, Tiruchirappalli, Tamilnadu, India. 2 Associate Professor, Department of Anatomy, KAPV Government Medical College, Tiruchirappalli, Tamilnadu, India. Correspondence Address: Dr.P.S.Chitra.M.S. (Anatomy), Associate Professor Of Anatomy, KAPV Government Medical College, Tiruchirappalli, Tamilnadu, India. Mobile No:  +918344767640. E-Mail:  pschitraezhilko@gmail.Com ABSTRACT Background:    Variations   in   the   morphology   of   the   upper   limb   muscles   are   not   uncommon.   These   variant   muscles   may   compress   the   adjacent   neurovascular structures   by   their   anomalous   positions.   The   knowledge   of   supernumerary   heads   of   biceps   brachii,   variant   bicipital   aponeurosis   and      an   abnormal tendinous   insertion   of   coracobrachialis      may      cause   clinical   conditions   like   median   nerve   entrapment,   compression   of   brachial   artery,   pronator   syndrome etc. Materials   and   Methods :   The   present   study   was   undertaken   to   observe   the   anomalous   origin   and   insertion   of   upper   limb   muscles   and   their   relation   to neurovascular   structures   in   vicinity.   This   study   was   carried   out   in   60   upper   limbs   of   30   formalin   fixed   human   cadavers   in   the   Department   of   Anatomy,   KAPV Government Medical College, Trichy. Results :      Among   the   sixty   upper   limbs,   variations   were   found   in   three   separate   limbs.      The   variations   included   an   accessory   head   of   biceps   brachii,   a muscular   slip   from   the   bicipital   aponeurosis   which   gave   extensions   to   the   forearm   muscles   and      an   anomalous   origin   and      tendinous   extension   of coracobrachialis muscle to the medial epicondyle of humerus. Conclusion:    Knowledge   of   supernumerary   heads   of   biceps   brachii,   accessory   slips   from   bicipital   aponeurosis   and   anomalous   origin   and   insertion   of coracobrachialis   is   essential   in   preoperative   diagnosis   and   surgery   of   upper   limbs,   as   they   may   cause   compression   of   neurovascular   structures   like   brachial artery, median nerve and ulnar nerve. KEY WORDS: Accessory head of biceps, bicipital aponeurosis, anomalous coracobrachialis, neurovascular compression. References 1 . 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