Anomalous pronator quadratus muscle: a case report

The pronator quadratus (PQ) muscle is one of the deeper muscle of the front of the forearm which originates from the oblique ridge in the lower part of the anterior surface of the shaft of the ulna and its adjoining medial area. The muscle inserts into the lower part of the anterior surface of the radius. In the present study, we observed an anomalous PQ muscles on both sides of a 52-year-old male cadaver during routine dissection. The muscle had dual origin from the ulna as well from the radius, and the two different bands of muscles had different directions of fibres in the downwards direction. Anomalies pertaining to the PQ muscle are not well documented in standard anatomy textbooks and the only source of information regarding its variations are found in research reports. The dual origin of the PQ as observed in the present study may be important from an anthropological point of view. Anatomical knowledge of the variations of the PQ may be beneficial for hand surgeons.