Final answer:
The rectus femoris, part of the quadriceps femoris group, is the muscle that crosses the hip and knee anteriorly and aids in extending the leg at the knee and flexing the thigh at the hip.
Step-by-step explanation:
The muscle that both crosses the hip and knee anteriorly is the rectus femoris. This muscle is part of the quadriceps femoris group, which is located in the anterior compartment of the thigh. The quadriceps group comprises four muscles: rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. Notably, the rectus femoris is responsible for extending the leg at the knee and aiding in flexing the thigh at the hip. If you're seeking to address a weakness in this muscle, exercises such as squats, lunges, and leg presses can be effective, as they specifically target the quadriceps, including the rectus femoris.