Final answer:
The semimembranosus and semitendinosus muscles attach on the medial side of the knee. These muscles are part of the hamstrings group responsible for flexing the knee and their attachment helps in the stability and biomechanics of the knee joint.
Step-by-step explanation:
The semimembranosus and semitendinosus muscles are two of the three hamstring muscles located in the posterior compartment of the thigh. These muscles are responsible for flexing the knee, and they both attach on the medial side of the knee. More specifically, the semitendinosus and semimembranosus tendons insert onto the medial surface of the proximal tibia. This is distinct from the lateral side of the knee joint, which includes structures such as the lateral meniscus and lateral collateral ligament.
Answering the question, the semimembranosus and semitendinosus attach on the medial side of the knee. This side also holds important structures related to the knee joint, such as the medial meniscus which is attached to the tibial collateral ligament and provides padding and support between the femoral condyles and tibial condyles. Understanding these connections is crucial as they play a significant role in the biomechanics and stability of the knee joint.