quadriceps

(kwŏd'rĭ-sĕps')
n.
The large four-part extensor muscle at the front of the thigh.

[QUADRI- + (BI)CEPS.]

quadricipital quad'ri·cip'i·tal (-sĭp'ĭ-tl) adj.

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quads

A group of four muscles (rectus femoris, vastus intermedius, vastus lateralis, and vastus medialis) which extend down the front of the thigh. The rectus femoris originates in the pelvis but the others originate from different points on the thigh bone. The four muscles join in a single tendon which crosses the knee cap to insert onto the shin bone. They are usually the most powerful muscles in the body and are the major extensors for straightening the leg. They play a vital role in any activity that involves running, walking, jumping, or even standing. Overextension, for instance when kicking, commonly results in the quads being strained (quadriceps muscle-pull). The leg hurts when touched and feels sore when the quads contract, for example, when going up stairs, hill running or doing squats. Overuse can also lead to a strain in the tendon, causing pain just above the knee cap. The quads are also actively involved in restraining the leg during downhill movements; the muscles contract eccentrically to resist the pull of gravity. Consequently, excessive downhill running is a common cause of muscle soreness in the quads. See also Q-angle.

The full name quadriceps femoris, or commonly ‘quads’, refers to the mass of muscle with four ‘heads’, partly surrounding the femur in the front of the thigh. This is the muscle that primarily extends the leg, straightening and stabilizing the knee by virtue of its strong attachments around the front and sides of the joint and to the tibia below it. Also, because part of it spans the front of the hip joint, it assists other muscles around the hip in maintaining an erect posture. The quads are thus essential simply for standing and for rising to standing, as well as for walking and running. The four components are partly distinct muscles with individual names: the vastus lateralis, the largest, lies mainly on the outer side, covering the deeper vastus intermedius; the vastus medialis lies on the inner side; the fourth muscle is attached to the pelvic bone above the hip and thence runs a straight course down the thigh — hence its name, rectus femoris — to end in a tendon that continues into the common quadriceps tendon in the front above the knee. The vastus muscles are attached above to the femur itself. Above the knee they curve in from the sides, accounting for the fleshy masses on either side just above the kneecap (patella), to be linked by fibrous sheets to the sides of the patella and to join the quadriceps tendon. This thick tendon is attached to the top of the patella, but also its strong fibrous extensions carry on downwards, embedding the patella within them, and linking up with the patellar tendon below it (the one that is tapped to elicit a knee-jerk reflex). This in turn is attached to the top of the tibia.

— Sheila Jennett

See musculo-skeletal system. See also hip; knee; posture; reflexes; walking.

Having four heads; refers to quadriceps muscle.

• q. reflex — see patellar reflex.

For a list of words related to quadriceps, see:

• Muscles - quadriceps: muscle at front of thigh

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See words rhyming with "quadriceps."

Dansk (Danish)
n. - (med.) quadriceps

Nederlands (Dutch)
vierhoofdige dijspier (quadriceps)

Français (French)
n. - quadriceps

Deutsch (German)
n. - Quadriceps (vierköpfiger Oberschenkelmuskel)

Ελληνική (Greek)
n. - (ανατ.) τετρακέφαλος μυς

Italiano (Italian)
quadricipite

Português (Portuguese)
n. - quadriceps (m) (músculo da coxa)

Русский (Russian)
четырехглавая мышца

Español (Spanish)
n. - cuadríceps

Svenska (Swedish)
n. - quadriceps (anat.)

中文（简体）(Chinese (Simplified))
四头肌

中文（繁體）(Chinese (Traditional))
n. - 四頭肌

한국어 (Korean)
n. - 대퇴 사두근

日本語 (Japanese)
n. - 四頭筋

العربيه (Arabic)
‏(الاسم) العضله في مقدم الفخذ المكونه من أربع رؤوس,‏

עברית (Hebrew)
n. - ‮שריר הירך‬

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