Which actions are performed by the semitendinosus muscle in the horse?

Which actions are performed by the semitendinosus muscle in the horse?

• A. Adducts limb
• B. Extends the hip and hock, and flex stifle
• C. Flexes hip and stifle
• D. Extends stifle

Answer: (B)

The semitendinosus is one of the hamstring muscles that crosses both the hip and the stifle, so its actions are on multiple joints. It pulls the femur backward to extend the hip, and at the stifle it acts to draw the tibia backward, which flexes the stifle. In the horse, this tendon also contributes to the hindlimb’s extension through connections in the calcanean (heel) region, aiding hock extension during propulsion. So the overall functional pattern is hip extension, stifle flexion, with a possible secondary role in helping extend the hock via the calcanean/tendon system. Adduction is done by other muscles like gracilis or adductor, not by the semitendinosus. Flexing both hip and stifle would be unusual for this muscle’s primary actions, and extending the stifle is not its main role (that’s more the job of the quadriceps).

The semitendinosus is one of the hamstring muscles that crosses both the hip and the stifle, so its actions are on multiple joints. It pulls the femur backward to extend the hip, and at the stifle it acts to draw the tibia backward, which flexes the stifle. In the horse, this tendon also contributes to the hindlimb’s extension through connections in the calcanean (heel) region, aiding hock extension during propulsion. So the overall functional pattern is hip extension, stifle flexion, with a possible secondary role in helping extend the hock via the calcanean/tendon system.

Adduction is done by other muscles like gracilis or adductor, not by the semitendinosus. Flexing both hip and stifle would be unusual for this muscle’s primary actions, and extending the stifle is not its main role (that’s more the job of the quadriceps).