This image shows a close-up view of some of the major muscles of the ventral surface of the frog thigh seen on the previous page. Note again the sartorius (1) muscle that covers the anterior surface of the thigh, the adductor magnus (2) and gracilis major (3). Not seen on the previous page is the gracilis minor (4), a thin, strap-shaped muscle that covers the posterior margin of the thigh. This muscle has the same origin, insertion and action as the larger gracilis major, that is, it originates on the pubis, inserts on the tibiofibula and acts to extend the thigh and flex the shank.