The quadriceps, or quadriceps femoris, are a group of muscles located at the front of your thigh. They are the most voluminous muscle group in the human body and collectively are one of the most powerful muscles in the body. The quadriceps consist of four individual muscles: the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. The rectus femoris is the only quad muscle that spans the hip joint and knee joint, while the other three muscles work together to extend (straighten) the knee. The quadriceps also play a crucial role in walking, running, jumping, and squatting. They help you stand, walk, climb stairs, and squat in everyday life. The quadriceps are vulnerable to injuries, such as contusions (bruising) from blows to the front of your thigh, and quad strains or “pulled quads” can occur.