View source for Quadriceps

{{short description|Group of human leg muscle}}
{{Distinguish|quadratus femoris}}
{{Redirect|Quads|the poker term|List of poker hands#Four of a kind|other uses|Quad (disambiguation){{!}}Quad}}
{{Infobox muscle
| Name        = Quadriceps femoris muscle
| Latin       = musculus quadriceps femoris
| Image       = Quadriceps 3D.gif
| Caption     = Quadriceps femoris, with different muscles in different colors.
{{legend|#4287f5|''[[rectus femoris muscle|rectus femoris]]''}}
{{legend|yellow|''[[vastus lateralis muscle|vastus lateralis]]''}}
{{legend|lime|''[[vastus intermedius muscle|vastus intermedius]]''}}
{{legend|red|''[[vastus medialis]]''}}
| Image2      =
| Caption2    =
| Origin      = Combined [[rectus femoris muscle|rectus femoris]] and [[Vastus muscles|vastus]] muscles
| Insertion   = [[Tuberosity of the tibia|Tibial tuberosity]]
| Blood       = [[Femoral artery]]
| Nerve       = [[Femoral nerve]]
| Action      = [[Knee]] [[Anatomical terms of motion#Flexion and extension|extension]]; [[hip]] [[Anatomical terms of motion#Flexion and extension|flexion]] (rectus femoris only)
| Antagonist  =
}}
The '''quadriceps femoris muscle''' ({{IPAc-en|ˈ|k|w|ɒ|d|r|ᵻ|s|ɛ|p|s|_|ˈ|f|ɛ|m|ər|ᵻ|s}}, 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 [[List of extensors of the human body#Knee|extensor muscle of the knee]], forming a large fleshy mass which covers the front and sides of the [[femur]]. The name derives {{ety|la|four-headed muscle of the femur}}.

==Structure==
[[File:Quadriceps.png|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'),<ref name=":0" /><ref>{{Citation|last=Chaitow|first=Leon|title=Chapter 13 - The knee|date=2011-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780443068157000139|work=Clinical Application of Neuromuscular Techniques, Volume 2 (Second Edition)|pages=447–501|editor-last=Chaitow|editor-first=Leon|place=Oxford|publisher=Churchill Livingstone|language=en|doi=10.1016/b978-0-443-06815-7.00013-9|isbn=978-0-443-06815-7|access-date=2020-12-23|last2=DeLany|first2=Judith|editor2-last=DeLany|editor2-first=Judith|url-access=subscription}}</ref> with the first superficial to the other three over the [[femur]] (from the [[trochanter]]s to the [[condyle]]s):
* The [[rectus femoris muscle]] occupies the middle of the thigh, covering most of the other three quadriceps muscles.<ref name=":0">{{Citation|last=Bakkum|first=Barclay W.|title=Chapter 4 - Muscles That Influence the Spine|date=2014-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780323079549000049|work=Clinical Anatomy of the Spine, Spinal Cord, and Ans (Third Edition)|pages=98–134|editor-last=Cramer|editor-first=Gregory D.|place=Saint Louis|publisher=Mosby|language=en|doi=10.1016/b978-0-323-07954-9.00004-9|isbn=978-0-323-07954-9|access-date=2020-12-23|last2=Cramer|first2=Gregory D.|editor2-last=Darby|editor2-first=Susan A.|url-access=subscription}}</ref> It originates on the [[ilium (bone)|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).<ref name=":0" />
* The [[Vastus medialis|vastus medialis muscle]] is on the ''medial side'' of the femur (i.e. on the inner part thigh).<ref name=":0" />
* The [[vastus intermedius muscle]] lies between vastus lateralis and vastus medialis on the ''front'' of the femur (i.e. on the top or front of the thigh), but deep to the rectus femoris muscle. Typically, it cannot be seen without dissection of the rectus femoris.<ref name=":0" />

===Attachments===
The rectus femoris arises from the [[anterior inferior iliac spine]] and from the superior edge of the [[acetabulum]].<ref name=":0" /> It is thus a [[biarticular muscle]]. The other parts of the quadriceps arise from the surface of the femur. All four parts of the quadriceps muscle ultimately insert into the [[tuberosity of the tibia]] via the [[patella]], where the [[quadriceps tendon]] becomes the [[patellar tendon]].<ref name=":0" />

===Other muscles===
There is a small fifth muscle of the quadriceps complex—the [[articularis genus muscle]]—that is not often included.

In addition, [[cadaver]] studies have confirmed the presence of a sixth muscle, the [[Tensor vastus intermedius muscle|tensor vastus intermedius]].<ref name="Grob_2016">{{cite journal|last1=Grob|first1=K|last2=Ackland|first2=T|last3=Kuster|first3=MS|last4=Manestar|first4=M|last5=Filgueira|first5=L|title=A newly discovered muscle: The tensor of the vastus intermedius|journal=Clinical Anatomy|date=6 January 2016|volume=29|issue=2|pages=256–263|doi=10.1002/ca.22680|pmid=26732825|s2cid=38157592|url=http://doc.rero.ch/record/258954/files/fil_ndm.pdf}}</ref> 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.<ref name="Grob_2016" /> Historically considered a part of the vastus lateralis muscle, the tensor vastus intermedius muscle is innervated by an independent branch of the [[femoral nerve]] and its tendinous belly can be separated from the vasti lateralis and intermedius muscles in most cases.<ref name="Grob_2016" />

===Innervation===
The quadriceps femoris is innervated by the femoral nerve, which originates from L2, L3, L4.<ref name=":0" /><ref name=":1">{{Citation|last=Felten|first=David L.|title=9 - Peripheral Nervous System|date=2016-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780323265119000096|work=Netter's Atlas of Neuroscience (Third Edition)|pages=153–231|editor-last=Felten|editor-first=David L.|place=Philadelphia|publisher=Elsevier|language=en|doi=10.1016/b978-0-323-26511-9.00009-6|isbn=978-0-323-26511-9|access-date=2020-12-23|last2=O'Banion|first2=M. Kerry|last3=Maida|first3=Mary Summo|editor2-last=O'Banion|editor2-first=M. Kerry|editor3-last=Maida|editor3-first=Mary Summo|url-access=subscription}}</ref>

==Function==
All four quadriceps are powerful [[List of extensors of the human body|extensors]] of the knee joint.<ref name=":0" /><ref name=":1" /> They are crucial in [[walking]], [[running]], [[jumping]] and [[Squatting position|squatting]]. Because the rectus femoris attaches to the ilium, it is also a flexor of the hip.<ref name=":0" /><ref name=":1" /> This action is also crucial to walking or running, as it swings the leg forward into the ensuing step. The quadriceps, specifically the vastus medialis, play the important role of stabilizing the patella and the knee joint during [[gait]].<ref name="Kisner">Therapeutic Exercises, Carolyn Kisner & Lynn A. Colby, 5th ed. (2002) 692-93.</ref>

==Clinical significance==
The quadriceps femoris muscle is a target for [[manual therapy]] and [[physical therapy]] from [[Repetitive strain injury|repetitive strain injuries]], such as from [[skiing]].<ref>{{Citation|last=Jelvéus|first=Anders|title=5 - Sports massage applications for different sports|date=2011-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780443101267000058|work=Integrated Sports Massage Therapy|pages=61–73|editor-last=Jelvéus|editor-first=Anders|place=Edinburgh|publisher=Churchill Livingstone|language=en|doi=10.1016/b978-0-443-10126-7.00005-8|isbn=978-0-443-10126-7|access-date=2020-12-23|url-access=subscription}}</ref>

The quadriceps femoris muscle is the most common site of [[myositis ossificans]].<ref>{{Citation|last=Landes|first=Caren J.|title=CHAPTER 73 - Paediatric musculoskeletal imaging|date=2011-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780702031311000730|work=Clinical Ultrasound (Third Edition)|pages=1497–1513|editor-last=Allan|editor-first=Paul L.|place=Edinburgh|publisher=Churchill Livingstone|language=en|doi=10.1016/b978-0-7020-3131-1.00073-0|isbn=978-0-7020-3131-1|access-date=2020-12-23|editor2-last=Baxter|editor2-first=Grant M.|editor3-last=Weston|editor3-first=Michael J.|url-access=subscription}}</ref>

==Society and culture==

===Training===
[[File:LegExtensionMachineExercise.JPG|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 (exercise)|squat]], [[leg press]], and [[leg extension]].{{Cn|date=April 2025}}

==Etymology==
The proper Latin plural form of the adjective ''quadri{{wikt-lang|la|-ceps|ceps}}'' 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.{{Cn|date=April 2025}}

==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==
{{Anatomy-terms}}
* [[Hamstring]]
* [[Gluteal muscles]]

==References==
{{Reflist}}

==External links==
{{Commons}}
* {{DukeOrtho|Quadriceps_muscle}}
* {{cite web|url=http://www.tk.de/rochelexikon/pics/s39960.000-1.html|title=Anatomy diagram: 39960.000-1|work= Roche Lexicon - illustrated navigator|publisher= Elsevier|archive-url=https://web.archive.org/web/20140101000000/http://www.tk.de/rochelexikon/pics/s39960.000-1.html|archive-date=2014-01-01}}

{{Muscles of lower limb}}
{{Authority control}}

[[Category:Knee extensors]]
[[Category:Thigh muscles]]
[[Category:Anterior compartment of thigh]]
[[Category:Muscles of the lower limb]]