It is one of the four muscles that make up the quadriceps femoris muscle group.

Here's a more detailed breakdown:

* Origin: It originates from the anterior inferior iliac spine (AIIS) and the superior margin of the acetabulum (the socket of the hip joint).

* Insertion: It inserts into the patella (kneecap) via the quadriceps tendon, and continues down as the patellar ligament to the tibial tuberosity (a bony prominence on the shinbone).

The rectus femoris is unique among the quadriceps muscles because it crosses two joints: the hip and the knee. This allows it to perform both hip flexion (bringing the thigh towards the torso) and knee extension (straightening the leg).