Muscles of the Hip and Thigh

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Now we are looking at the south end of a dog going north. Dorsal is still up but medial is now right. As I said before, most of the caudolateral aspect of the thigh consists of the biceps femoris muscle (A). As we course medially, we encounter the semitendinosis muscle (B), the semimembranosis muscle (C) and the gracillis muscle (D), which is covering much of the semimembranosis muscle.

A, B, and C are called the ham-string muscles. I don't know...maybe it has something to do with the way they tie ham with a string. Anyway, these muscles each act upon multiple joints. Can you tell me their actions? They are all innervated by the sciatic nerve. We will consider the gracilis muscle more closely with the medial muscles of the thigh.

The biceps femoris, semitendinosus and semimembranosus muscles act together to extend the hip and flex the stifle. The cranial parts of both the biceps femoris and semimembranosis muscles may also extend the stifle. This action by these two muscles (extending the stifle) is more to support the stifle when weight bearing, rather than an action while the limb is elevated, so don't get too hung up on this action. The biceps femoris and semitendinosus muscles also act to extend the hock by their attachment to the tuber calcanei via the common calcaneal tendon (Achilles tendon)..