Structure located under peroneus tertius.

Structure located under peroneus tertius.

• A. Cranial tibial tendon
• B. Navicular ligaments
• C. Seasmoidean ligaments
• D. Gracilis

Answer: (A)

In the horse’s stay apparatus, the movement of the stifle and hock is coordinated by a reciprocal mechanism: the peroneus tertius runs along the craniolateral leg, and its relation with the tendon of the cranial tibial muscle is key. The structure located under the peroneus tertius is the cranial tibial tendon. This tendon passes beneath the peroneus tertius as the two tendons help link stifle and hock motion, so that when the stifle flexes, the hock flexes in tandem, and when the stifle extends, the hock extends as well. The other options aren’t involved in this particular relationship: navicular ligaments lie in the hoof region, sesamoidean ligaments stabilize the fetlock, and gracilis is a thigh muscle, not part of the hock-stifle reciprocal mechanism.

In the horse’s stay apparatus, the movement of the stifle and hock is coordinated by a reciprocal mechanism: the peroneus tertius runs along the craniolateral leg, and its relation with the tendon of the cranial tibial muscle is key. The structure located under the peroneus tertius is the cranial tibial tendon. This tendon passes beneath the peroneus tertius as the two tendons help link stifle and hock motion, so that when the stifle flexes, the hock flexes in tandem, and when the stifle extends, the hock extends as well. The other options aren’t involved in this particular relationship: navicular ligaments lie in the hoof region, sesamoidean ligaments stabilize the fetlock, and gracilis is a thigh muscle, not part of the hock-stifle reciprocal mechanism.