Plantar fascia
873391
193943235
2008-02-25T15:46:17Z
Gene Nygaard
146986
lowercase unit name, dab, improper symbols, dup links, precision
{{Infobox Anatomy |
Name = Plantar fascia |
Latin = aponeurosis plantaris |
GraySubject = 131 |
GrayPage = 490 |
Image = Gray443.png |
Caption = Muscles of the sole of the foot. First layer. (Plantar aponeurosis visible at top center.) |
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Caption2 = |
Precursor = |
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Artery = |
Vein = |
Nerve = |
Lymph = |
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DorlandsPre = a_53 |
DorlandsSuf = 12146774 |
}}
The '''[[Anatomical terms of location#Relative directions in the limbs|plantar]] [[fascia]]''' (or '''plantar [[aponeurosis]]''') is the thick [[connective tissue]] which supports the arch of the foot. It runs from the tuberosity of the [[calcaneus]] forward to the heads of the [[metatarsal]] bones. It is the source of the painful condition [[plantar fasciitis]].
==Anatomy of the plantar fascia ==
[[Image:PF-PlantarDesign.jpg|thumb|250px|left|Anatomical diagrams illustrating the components of the plantar fascia.]]
The ''plantar fascia'' is a broad structure that spans between the medial calcaneal tubercle and the proximal [[phalanges]] of the toes. There is still some debate as to whether it is deep [[fascia]] or an [[aponeurosis]]. The Dorland’s Medical Dictionary defines an aponeurosis as:.(i) a white, flattened or ribbon-like tendinous expansion, serving mainly to connect a muscle with the parts that it moves, (ii) a term formerly applied to certain fasciae. Further, it defines the plantar [[aponeurosis]] as: bands of [[fibrous tissue]] radiating toward the bases of the toes from the medial process of the tuber calcanei; also called the ''plantar fascia''. The plantar fascia is made up of predominantly longitudinally oriented [[collagen]] fibers. There are three distinct structural components: the medial component, the central component, and the lateral component (see the figure on your right)). The central component is the largest and most prominent.
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 impact on each other. Nevertheless, there is an indirect relationship whereby if the toes are [[dorsiflex]]ed, 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 splinting being applied to the [[gastrocnemius]]/[[soleus]] muscle unit.
==Biomechanics of the plantar fascia ==
{{Unreferenced|date=April 2007}}
[[Image:PF-PlantarMove.jpg|thumb|250px|left|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 [[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 1189 ± 244 [[newton]]s (121 ± 24 [[lbf]]/ 55 ± 11 [[kgf]]). Interestingly, 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 [[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 683 newtons (69.6 kgf/31.6 lbf). Surgical release also significantly increases both stress in the 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.
The ''plantar fascia'' also has an important role in dynamic function during [[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 9% to 12% elongation between mid-stance and toe-off. During this phase the ''plantar fascia'' behaves like a 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 [[dorsiflex]]ed 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 likened 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]]. Therefore, the ''plantar fascia'' has a number of roles, the most important of these including supporting the arch of the foot and contributing to the [[windlass]] mechanism.
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==See also==
* [[Fascia]]
*[[Plantar Fasciitis]]
==External links==
* {{DukeOrtho|plantar_fascia}}
* {{NormanAnatomy|soleoffoot}} ({{NormanAnatomyFig|soleoffoot1}})
* [http://www.hipusa.com/eTools/webmd/A-Z_Encyclopedia/plantarfasciitisbasics.htm Diagram at hipusa.com]
* [http://www.patient.co.uk/showdoc/Pilsinl/017.jpg Diagram at patient.co.uk]
{{Lower limb general}}
[[Category:Pelvic limb anatomy]]
[[de:Aponeurosis plantaris]]
[[fr:Fascia plantaire]]