The quadriceps femoris muscle (, also called the quadriceps extensor, quadriceps or quads) is a large muscle group that includes the four prevailing muscles on the front of the thigh. It is the sole extensor muscle of the knee, forming a large fleshy mass which covers the front and sides of the femur. The name derives .

Structure

left|thumb|200px|The quadriceps consists of four separate muscles([[vastus intermedius muscle is not shown as it is deep to rectus femoris muscle)]]

Parts

The quadriceps femoris muscle is subdivided into four separate muscles (the 'heads'), with the first superficial to the other three over the femur (from the trochanters to the condyles):

  • The rectus femoris muscle occupies the middle of the thigh, covering most of the other three quadriceps muscles. It originates on the ilium. It is named for its straight course.
  • The vastus lateralis muscle is on the lateral side of the femur (i.e., on the outer side of the thigh). While this muscle has a variable presentation, it consistently originates at the proximal femur, runs between the vastus lateralis and vastus intermedius muscles, and inserts distally at the medial aspect of the patellar base.

Function

All four quadriceps are powerful extensors of the knee joint.

Clinical significance

The quadriceps femoris muscle is a target for manual therapy and physical therapy from repetitive strain injuries, such as from skiing.

The quadriceps femoris muscle is the most common site of myositis ossificans.

Society and culture

Training

thumb|The leg extension is an isolation exercise for the quadriceps.

In strength training, the quadriceps are trained by several leg exercises including the squat, leg press, and leg extension.

Etymology

The proper Latin plural form of the adjective quadri would be quadricipites. In modern English usage, quadriceps is used in both the singular and plural form. The singular form quadricep, produced by back-formation, is frequently used.

Additional images

<gallery>

File:Knee diagram.svg|The quadriceps tendon connects to the top part of the kneecap (patella)

File:Gray432 color.png|Cross-section through the middle of the thigh

File:Gray1238.png|The quadriceps forms the bulk of front part of the thigh

</gallery>

See also

  • Hamstring
  • Gluteal muscles

References