Muscle · Hips

Rectus femoris

Musculus rectus femoris

Rectus femoris is the middle strap of the quadriceps — the part of the front thigh you can see standing proud between the two vastus muscles. It is the only one of the four that crosses the hip as well as the knee, running from the front of the pelvis all the way to the kneecap, and that single fact explains most of what it does and most of the trouble it gets into. Because it spans two joints, its length depends on where the hip is: kicking a ball asks it to extend the knee while the hip is already extending behind, which stretches it at both ends at once. That is exactly the position it tends to strain in, and it is why a stiff-feeling front thigh can pull on the pelvis and be felt as hip or low-back tightness rather than as a thigh problem.