Final answer:
The biceps femoris forms the lateral boundary of the popliteal fossa.
Step-by-step explanation:
The biceps femoris forms the lateral boundary of the popliteal fossa. The popliteal fossa is a diamond-shaped space located at the back of the knee joint. It is bounded by the biceps femoris muscle on the lateral side, the semimembranosus and semitendinosus muscles on the medial side, the gastrocnemius muscle superiorly, and the fascia covering the popliteus muscle inferiorly.