Which muscle's action includes both stifle extension and knee stabilization?

The correct response is that both the vastus lateralis and vastus medialis are involved in stifle extension and stabilization of the knee joint. These muscles are part of the quadriceps group, which plays a vital role in extending the knee.

The vastus lateralis is located on the outer side of the thigh, while the vastus medialis is situated on the inner side. Together, they work to extend the stifle joint (the knee in quadrupeds) during activities such as standing up, walking, or running. Additionally, these muscles contribute to the stability of the knee by maintaining proper patellar alignment and preventing lateral displacement of the patella.

In terms of anatomical function, the vastus lateralis helps extend the leg and stabilize the knee, while the vastus medialis is crucial for locking the knee in certain positions, particularly in the last few degrees of extension. Therefore, both muscles collaborate to perform the essential actions of extending the stifle and ensuring stability, making this the most comprehensive answer.