View source for Plantar fascia

{{short description|Aponeurosis of the sole of the foot}}
{{For|the disorder|Plantar fasciitis}}
{{Infobox anatomy
| Name        = Plantar fascia
| Latin       = aponeurosis plantaris
| Greek       =
| Image       = 1124 Intrinsic Muscles of the Foot b.png
| Alt         = anatomical diagram of foot
| Caption     = Muscles of the sole of the foot. First layer (closest to the skin on the sole of the foot). Plantar aponeurosis visible at top center.
| Width       =
| Image2      =
| Caption2    =
| Precursor   =
| System      =
| Artery      =
| Vein        =
| Nerve       =
| Lymph       =
}}
The '''plantar fascia''' or '''plantar aponeurosis'''<ref name="The Free Dictionary">{{Cite encyclopedia |title=aponeurosis plantaris |encyclopedia=[[The Free Dictionary]] |publisher=[[Farlex]] |url=https://medical-dictionary.thefreedictionary.com/aponeurosis+plantaris |access-date=2023-06-10 |date=n.d. |language=en}}</ref> is the thick [[connective tissue]] [[aponeurosis]] which supports the [[Arches of the foot|arch]] on the bottom ([[plantar]] side) of the [[foot]]. Recent studies suggest that the plantar fascia is actually an [[aponeurosis]] rather than true [[fascia]].{{zwj}}{{Citation needed|date=June 2023}} It runs from the [[tuberosity]] of the [[calcaneus]] (heel bone) forward to the heads of the [[metatarsal bones]] (the bone between each [[toe]] and the bones of the mid-foot).

==Anatomy==
[[Image:PF-PlantarDesign.jpg|thumb|250px|left|alt=anatomical diagram|Anatomical diagrams illustrating the components of the plantar fascia.]]
[[File:Plantar aponeurosis - axial view.png|thumb|250px|left|alt=dissection photo|Dissection of the plantar aponeurosis:<br>LP, lateral part; CP, central part; MP, medial part; L, length; W, width.]]
[[File:Plantar aponeurosis - central.png|thumb|250px|left|alt=dissection photo|Five central part plantar aponeurosis bundles.]]

The plantar fascia is the thick central portion of the fascia investing the plantar muscles. It extends between the medial process of the {{langr|la|[[tuber calcanei]]}}<ref name="The Free Dictionary" /> and the proximal [[phalanges]] of{{Citation needed|date=June 2023}} the toes. It provides some attachment to the flexor muscles of the toes.{{zwj}}<ref name="The Free Dictionary" />

Distally, the plantar fascia becomes continuous with the fibrous sheaths enveloping the flexor tendons passing to the toes. At the anterior extremity of the sole{{snd}} inferior to the heads of the metatarsal bones{{snd}} the plantar aponeurosis forms the [[superficial transverse metatarsal ligament]].{{zwj}}<ref name="Moore-20112">{{Cite book |last=Moore |first=Keith L. |title=Essential Clinical Anatomy |last2=Dalley |first2=Arthur F. |last3=Agur |first3=Anne M. R. |publisher=[[Lippincott Williams & Wilkins]] |year=2017 |isbn=978-1496347213 |pages=769}}</ref>

=== Structure ===
The plantar fascia is made up of predominantly longitudinally oriented [[collagen fiber]]s. There are three distinct structural components: the '''medial component''', the '''central component''' ('''plantar aponeurosis'''), and the '''lateral component''' (see diagram at right). The central component is the largest and most prominent.

=== Development ===
In younger people the plantar fascia is also intimately related to the [[Achilles tendon]], with a continuous fascial connection between the two from the distal aspect of the Achilles to the origin of the plantar fascia at the [[calcaneal tubercle]]. However, the continuity of this connection decreases with age to a point that in the elderly there are few, if any, connecting fibers. There are also distinct attachments of the plantar fascia and the Achilles tendon to the [[calcaneus]] so the two do not directly contact each other. Nevertheless, there is an indirect relationship whereby if the toes are [[dorsiflexed]], the plantar fascia tightens via the [[windlass]] mechanism. If a tensile force is then generated in the Achilles tendon it will increase tensile strain in the plantar fascia. Clinically, this relationship has been used as a basis for treatment for plantar fasciitis, with stretches and night stretch [[splint (medicine)|splinting]] being applied to the {{langr|grc|[[gastrocnemius]]}}/[[soleus muscle]] unit.

==Function==
[[File:Plantar Bewegung.gif|thumb|250px|left|alt=anatomical diagram|The effect of dorsiflexing the toes on arch height (A). The windlass mechanism (B).]]

The plantar fascia contributes to support of the arch of the foot by acting as a [[tie-rod]], where it undergoes tension when the foot bears weight. One [[biomechanics|biomechanical]] model estimated it carries as much as 14% of the total load of the foot. In an experiment using [[cadaver]]s, it was found that failure of the plantar fascia averaged at loads of {{val|118|244|u=[[newton (unit)|newtons]]}}<ref>{{Cite journal |last=H. B. Kitaoka |last2=Z. P. Luo |last3=E. S. Growney |last4=L. J. Berglund |last5=K. N. An |date=October 1994 |title=Material properties of the plantar aponeurosis |journal=Foot & Ankle International |volume=15 |issue=10 |pages=557–560 |doi=10.1177/107110079401501007 |pmid=7834064 |s2cid=45264072}}</ref> ({{convert|118|±|244|N|kgf lbf|0|abbr=off|lk=out|disp=out}}). Failure most often occurred at the proximal attachment to the calcaneus, which is consistent with the usual location of symptoms (''[[i.e.]]'' in plantar fasciitis). Complete [[plantar fascial rupture|rupture]] or surgical release of the plantar fascia leads to a decrease in arch stiffness and a significant collapse of the [[longitudinal arch of the foot]]. By modeling it was predicted such conditions would result in a 17% increase in vertical displacement and a 15% increase in horizontal elongation of the foot when it was loaded at {{convert|683|N|kgf lbf|0}}.{{zwj}}<ref>{{Cite journal |last=G. A. Arangio, C. Chen and W. Kim |date=June 1997 |title=Effect of cutting the plantar fascia on mechanical properties of the foot |journal=[[Clinical Orthopaedics and Related Research]] |volume=339 |issue=339 |pages=227–231 |doi=10.1097/00003086-199706000-00031 |pmid=9186224 |s2cid=19194412}}</ref> Surgical release also significantly increases both stress in the [[plantar ligaments (disambiguation)|plantar ligaments]] and plantar pressures under the [[metatarsal]] heads. Although most of the figures mentioned above are from either [[cadaver]] studies or investigations using models, they highlight the relatively large load the plantar fascia is subjected to while contributing to the structural integrity of the foot.

===Gait===
The plantar fascia also has an important role in [[dynamic function]] during [[gait (human)|gait]]. It was found the plantar fascia continuously elongated during the contact phase of gait. It went through rapid elongation before and immediately after mid-stance, reaching a maximum of {{val|9|to|12|u=%}} elongation between mid-stance and toe-off.{{zwj}}<ref>{{Cite journal |last=Amit Gefen |date=March 2003 |title=The in vivo elastic properties of the plantar fascia during the contact phase of walking |journal=Foot & Ankle International |volume=24 |issue=3 |pages=238–244 |doi=10.1177/107110070302400307 |pmid=12793487 |s2cid=2829705}}</ref> During this phase the plantar fascia behaves like a [[spring (device)|spring]], which may assist in conserving energy. In addition, the plantar fascia has a critical role in normal mechanical function of the foot, contributing to the "[[windlass]] mechanism". When the toes are [[dorsiflexed]] in the propulsive phase of gait, the plantar fascia becomes tense, resulting in elevation of the [[longitudinal arch]] and shortening of the foot (see 3A). One can liken this mechanism to a cable being wound around the drum of a windlass (see 3B); the plantar fascia being the cable, the metatarsal head the drum, and the handle, the [[proximal phalanx]].

{{Clear}}

==Clinical significance==
===Plantar fasciitis===
{{Main|Plantar fasciitis}}
* [[Plantar fasciitis]] is an often painful degenerative process of the plantar fascia.
** [[Calcaneal spur]] (heel spur) is a small calcified bone extension ([[osteophyte]]) located on the inferior aspect of the calcaneus or on the back of the heel at the insertion of the Achilles tendon. The condition is typically a response to plantar fasciitis over a period of time. Visualized on x-ray. It is mistaken for a sharp piece or horn of bone sticking out of the heel and instead is actually calcification of the plantar fascia, mistakenly thought to be a bone spur. It may also be related to [[ankylosing spondylitis]], typically in children.

===Other===
* [[Plantar fibromatosis]] is a relatively uncommon non-malignant thickening of the plantar fascia.
* [[Psoriatic arthritis]] is a type of inflammatory arthritis that may affect the plantar fascia.
* [[Plantar fascial rupture]]/tear is a relatively uncommon painful tearing of the plantar fascia. The tear can be full or partial.

== Additional images ==
<gallery>
File:Gray443.png|alt=anatomical diagram|The plantar fascia (also known as the plantar aponeurosis) is located superficially plantar side of the foot.
</gallery>

==See also==
{{Commons}}
{{Anatomy-terms}}

==References==
{{Reflist}}

==External links==
{{Wiktionary}}
* {{DukeOrtho|Plantar_fascia}}
* {{NormanAnatomy|soleoffoot}} ({{NormanAnatomyFig|soleoffoot1}})
* [http://patient.info/health/heel-and-foot-pain-plantar-fasciitis Heel Pain Symptoms. Plantar Fasciitis diagnosis and treatment | Patient]; plantar fasciitis at Patient.info

{{Muscles of lower limb}}
{{Soft tissue disorders}}
{{Authority control}}

{{DEFAULTSORT:Plantar Fascia}}
[[Category:Lower limb anatomy]]
[[Category:Fascia]]