Quadriceps femoris muscle
The quadriceps femoris (quadriceps, quadriceps extensor, guads or quads) includes the four prevailing muscles on the front of the thigh. It is the great extensor muscle of the knee, forming a large fleshy mass which covers the front and sides of the femur.
It is subdivided into separate portions, which have received distinctive names.
- Rectus femoris occupies the middle of the thigh, covering most of the other three quadriceps muscles. It originates on the ilium. It is named from its straight course.
- The other three lie deep to rectus femoris and originate from the body of the femur, which they cover from the trochanters to the condyles:
The quadriceps is also involved in Lombard's Paradox.
All four quadriceps are powerful extensors of the knee joint. They are crucial in walking, running, jumping and squatting. Because rectus femoris attaches to the ilium, it is also a flexor of the hip. This action is also crucial to walking or running as it swings the leg forward into the ensuing step.
Capsule of right knee-joint (distended). Lateral aspect.
Cross-section through the middle of the thigh.
Anterior aspect of right leg.
Front and medial aspect of right thigh.
Lateral aspect of right leg.
The leg extension is an isolation exercise.
- Anatomy of the Quadriceps Muscles - Fitstep.com