Study on Morphological Variations in Fibers of Pronator Quadratus Muscle

In standard textbook of Anatomy describes pronator quadratus (PQ) muscle fibers variations are not well documented. In 16 specimens (30.76%) we found superficial fibers with medial aponeurosis and deep fibers. Both this fibers were running parallel to each other directing downwards and laterally from ulna towards the radius. In 34 specimens (65.38%) we found superficial fibers in distal part of muscle were directing downwards and laterally from ulna towards the radius while the middle part fibers were more horizontally placed and the proximal muscle fibers were directing upwards and laterally. Deep fibers of the muscle were seen extending downward and laterally toward the radius more oblique to the direction of superficial fibers. In one specimen we found superficial fibers were directing downwards and laterally, but proximal and distal to the superficial fibers, deep fibers were seen originating about 2 cms proximal to the superficial fibers from the shaft of the ulna while the distal to the aponeurotic superficial fibers, deep fibers again appears as fleshy muscle from ulna extending downward toward the distal part of radius and also some of the fibers extend distally toward the capsule of wrist joint and get attached to it. In another specimen we found aponeurotic superficial fibers in distal part of muscle were directing downwards and laterally from ulna towards the radius while the middle part fibers were more horizontally placed and the proximal muscle fibers were directing upwards and laterally. Proximal to the superficial part of the muscle two separate superficial muscle fiber slips were seen extending toward the radius. Both muscle slips were having origin from ulna in continuation with superficial fibers of pronator quadrates muscle. Proximal muscle slip was quadrangular in shape and get inserted on anterior ridge of lower end of radius while distal triangular muscle slip get inserted on medial triangular surface of lower end of radius. So the detailed evaluation of pronator quadratus muscle is needed for knowledge to anatomist and during hand, orthopedic and plastic surgery.