An anomaly of the median artery associated with the anterior interosseous nerve syndrome.

The anterior interosseous nerve syndrome is characterized by paralysis of the flexor pollicis longus muscle, the flexor digitorum profundus muscle to the index and middle fingers, and the pronator quadratus muscle. The most common cause is entrapment of the anterior interosseous nerve near its origin from the median nerve by a variety of structures. Compression is most frequently caused by the deep head of the pronator teres muscle, or the fibrous arcade of the flexor digitorum superficialis muscle. Vascular compression has been reported infrequently. A patient with anterior interosseous nerve syndrome was found at operation to have the median artery passing through the anterior interosseous nerve just below the elbow. This artery has not previously been associated with the syndrome. A cadaver dissection confirmed the relationship.