Anomalous Third Head of Biceps Brachii Muscle and its Variant Insertion Compresses Surrounding Neurovascular Structure: A Rare Case Report

Biceps brachii  (BB) is one of the muscles  which  are subjected to many variations. Recently,  there  is a lot of information about  variations  in origin  but  also  some cases  are reported  on variations  in insertion  of BB. Presented  herein  was a case of BB muscle  having  both  variant  origin and  insertion  in the same  muscle.  The variant origin of BB was long and large at its third head (10.2 cm width and 4.9 cm breadth) which arises from mid-shaft of the humerus. More significantly, the medial portion  of the head  covers and conceals the lower portion  of median  nerve and brachial  artery as an arch which  continues medially  to be inserted  to the medial epicondyle of  the  humerus.  We  discuss  in this report,  the  possible  mechanism for neurovascular compression by this abnormal third head  of BB muscle and the variation  of BB from its origin  and  insertion.  Understanding these  variations  is highly significant in surgical  procedures around  elbow  joint and  upper  arm and it also pave the way for the differential diagnosis in nerve entrapment syndrome.