Pronator Teres Syndrome

Excerpt

Pronator teres syndrome (PTS), first described by Henrik Seyffarth in 1951, is caused by a compression of the median nerve (MN) by the pronator teres (PT) muscle in the forearm. The PT muscle is named because of its action and shape; it is a rounded muscle that pronates the forearm. In the majority of cases (66%), it arises from unequal two heads: the larger humeral head from the upper part of the medial epicondyle and the smaller ulnar head from the coronoid process of the ulna. They pass down to the forearm, form a common flexor tendon, and insert into the radial shaft. Before the two heads unite, the median nerve passes between them in 74% to 82% of the cases, innervating both heads from C6-7 roots. The absence of the ulnar head is rare (14%) and may reduce the risk of median nerve entrapment. Many individuals have additional fibrous brands within the two heads of the PT muscle. The anterior interosseous nerve (AIN) then branches from the MN about 5 to 8 cm distal to the medial epicondyle.