{"id":4095,"date":"2021-01-28T01:22:01","date_gmt":"2021-01-28T00:22:01","guid":{"rendered":"https:\/\/meddists.com\/learn\/pre-clinical\/anatomy\/lower-limb\/leg\/leg-muscles\/posterior-compartment\/"},"modified":"2021-02-06T19:12:58","modified_gmt":"2021-02-06T18:12:58","slug":"posterior-compartment","status":"publish","type":"page","link":"https:\/\/meddists.com\/learn\/pre-clinical\/anatomy\/lower-limb\/leg\/leg-muscles\/posterior-compartment\/","title":{"rendered":"Posterior compartment"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\"><div class=\"intro\">The largest compartment of the leg is the posterior, which is divided into two layers and comprises seven muscles. The layers are superficial and deep, separated by fascia.<\/div><\/p>\n\n\n\n<hr class=\"wp-block-separator\" \/>\n\n\n\n<ul class=\"wp-block-list\"><li>This group of muscles naturally antagonizes the anterior compartment.<\/li><li>The main functions of the muscles of this area are plantarflexion and inversion of the foot. <\/li><li>Due to the constant resistance against gravity during standing and when performing locomotion movements, the muscles that integrate this compartment of the leg are more strongly developed than the other groups.<\/li><\/ul>\n\n\n<span class=\"block-heading\" id=\"header_1\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Superficial layer<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_1\">\n\n\n<p class=\"wp-block-paragraph\">The&nbsp; muscles of this layer attach to the calcaneus bone shaping the typical \u201ccalf\u201d of the ankle. Their insertion follows the calcaneal tendon. By working together, these muscles move the body forward from the planted foot during the walk. When standing, elevate the body onto the toes.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The muscles that comprise the superficial layer of the posterior compartment are:<\/p>\n\n\n\n<ol class=\"wp-block-list\" type=\"1\"><li>The gastrocnemius<\/li><li>The plantaris<\/li><li>The soleus<\/li><\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">The three muscles receive innervation from the S1 and S2 branches of the tibial nerve.<\/p>\n\n\n<\/span><span class=\"block-heading\" id=\"header_2\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Gastrocnemius&nbsp;<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_2\">\n\n\n<p class=\"wp-block-paragraph\">The gastrocnemius muscle is the largest muscle of the leg, and locates superficially at the posterior compartment. It has two heads for its insertion: medial and lateral.<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>Medial head: originates from the distal femur, posterior to the adductor tubercle, and superior to the articular side of the medial condyle of the femur.&nbsp;<\/li><li>Lateral head: elongates from the superolateral surface of the femoral condyle.<ul><li>Both heads of the gastrocnemius join in the upper leg, where they merge to form a single belly, which inserts onto the calcaneus and shapes the soft tissue from the \u201ccalf\u201d.&nbsp;<\/li><li>In the lower part of the leg, the muscle belly combines with the soleus from the calcaneal tendon, a structure that finds insertion at the calcaneus.&nbsp;<\/li><li>When the edges of both heads face at the knee, creates the lateral and medial margins of the lowest surface of the popliteal fossa.&nbsp;<\/li><\/ul><\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">The main function of the gastrocnemius is to plantarflex the foot at the ankle joint, and flex the knee.<\/p>\n\n\n<\/span><span class=\"block-heading\" id=\"header_3\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Plantaris<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_3\">\n\n\n<p class=\"wp-block-paragraph\">The plantaris is a small, short, and spindle-shaped muscle with a long thin tendon. <\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>It originates from the inferior surface of the lateral supracondylar crest of the femur and the oblique popliteal ligament (at the knee joint) and finds its attachment in the posterior surface of the calcaneus.<\/li><li>It follows deep to the lateral head of the gastrocnemius, from where elongates its small tendon.<\/li><li>The continues between the gastrocnemius and soleus muscles until fuse with the medial surface of the calcaneal tendon.<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Just like the other two muscles of the superficial group, the plantaris plantarflex the foot at the ankle joint, and since also crosses the knee, acts as a flexor at that level.<\/p>\n\n\n<\/span><span class=\"block-heading\" id=\"header_4\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Soleus<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_4\">\n\n\n<p class=\"wp-block-paragraph\">The soleus is a large flat muscle located deep to the gastrocnemius.<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>It originates from the posterior surface of the head and proximal area of the neck of the fibula, on the adjacent end of the fibula, and from the soleal line and proximal medial border of the tibia<\/li><li>The soleus ends up merging with the calcaneal tendon in the lower leg until finds attachment to the calcaneus. <\/li><li>Its ligament narrows down between the attachments to the tibia and fibula, curving over the tibial nerve and popliteal vessels during its passage through the popliteal fossa.<\/li><li>Along with the gastrocnemius and plantaris, the soleus plantarflexes the foot at the ankle joint.<\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_5\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Deep layer<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_5\">\n\n\n<p class=\"wp-block-paragraph\">This group is separated from the superficial group by a layer of fascia. The deep group of the posterior compartment of the leg is integrated by the following muscles:\u00a0<\/p>\n\n\n\n<ol class=\"wp-block-list\" type=\"1\"><li>Popliteus&nbsp;<\/li><li>Flexor hallucis longus<\/li><li>Flexor digitorum longus&nbsp;<\/li><li>Tibialis posterior<\/li><\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">The typical tension of the muscles of this group forms the medial arch of the foot.<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>With the exception of the popliteus, the deep group act on the ankle and mainly on the foot. <\/li><li>The popliteus acts only on the knee joint.<\/li><li>The four muscles receive innervation from the tibial nerve and vascularization from the posterior tibial artery (branch of the popliteal artery).<\/li><li>The popliteus is the only exception, since receives direct supply from the popliteal artery, branch of the femoral artery.<\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_6\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Popliteus<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_6\">\n\n\n<p class=\"wp-block-paragraph\">The smallest of the muscles of the deep layer is the popliteus. This flat and triangular-shaped muscle is the most superior of the muscles of this group. Lies behind the knee joint and frames the floor of the popliteal fossa.<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>It originates from a tendon, which ascends laterally surrounding the joint of the capsule of the knee, following between the lateral meniscus and the fibrous membrane into a canal located at the lateral femoral condyle.<\/li><li>It inserts inferior to the origin of the soleus muscle.<\/li><li>The muscle extends downwards, crossing the lower surface of the knee.<\/li><li>The popliteus bursa lies between the posterior surface of the knee joint and the popliteal tendon.<\/li><li>Its function is to extend the knee when initiated the flexion (\u2018unlocking\u2019), and stabilize it by offering lateral rotation of the femur on the tibia.<\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_7\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Flexor hallucis longus<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_7\">\n\n\n<p class=\"wp-block-paragraph\">Located laterally at the leg, the flexor hallucis longus originates from the lower two-thirds of the posterior area of the fibula and the contiguous surface of the interosseous membrane.<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>The fibers of the flexor hallucis longus merge inferiorly to compose a larger tendon.<\/li><li>The tendon follows posterior to the distal head of the tibia to go through a channel located on the posterior portion of the talus of the foot.<\/li><li>It inserts into the lower surface of the distal phalanx of the great toe.<\/li><li>The function of the flexor hallucis longus is to flex the great toe. It might collaborate during plantarflexion of the foot at the ankle joint.<\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_8\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Flexor digitorum longus<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_8\">\n\n\n<p class=\"wp-block-paragraph\">The flexor digitorum longus is smaller than the flexor hallucis longus and locates medially in the posterior compartment of the leg.<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>Its tendon descends crossing posteriorly to the tendon of the tibialis posterior, close to the ankle joint, downwards through a canal posterior to the medial malleolus, to enter into the sole, to reach the medial portion of the foot to divides into four tendons.<\/li><li>Each of the four tendons finally inserts into the plantar surfaces of the distal phalanges of the digits II-V.<\/li><li>The flexor digitorum longus flexes perform the flexion of the lateral four toes.<\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_9\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Tibialis posterior<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_9\">\n\n\n<p class=\"wp-block-paragraph\">The tibialis posterior is the deepest of this group of muscles.<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>It originates from the posterior section of the interosseous membrane, and the posterior surfaces of the tibia and fibula.<\/li><li>It overlapped by the flexor hallucis longus and the flexor digitorum muscles.<\/li><li>The tendon of the tibialis posterior is crossed by the tendon of the flexor digitorum longus near the ankle.<\/li><li>The tendon continues forward posterior to the medial malleolus to find the medial surface of the foot.<\/li><li>It attaches to the plantar portion of the medial tarsal bones.<\/li><li>The tibialis posterior inverts and plantarflexes the foot. Also, it holds the medial arch of the foot during walking.<\/li><\/ul>\n<\/span><div id=\"the_titles\" style=\"display:none;\"><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Superficial layer<\/h3><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Gastrocnemius&nbsp;<\/h4><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Plantaris<\/h4><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Soleus<\/h4><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Deep layer<\/h3><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Popliteus<\/h4><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Flexor hallucis longus<\/h4><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Flexor digitorum longus<\/h4><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Tibialis posterior<\/h4><\/div>","protected":false},"excerpt":{"rendered":"<p>This group of muscles naturally antagonizes the anterior compartment. The main functions of the muscles of this area are plantarflexion and inversion of the foot. Due to the constant resistance against gravity during standing and when performing locomotion movements, the muscles that integrate this compartment of the leg are more strongly developed than the other [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":3971,"menu_order":2,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-4095","page","type-page","status-publish","hentry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.8 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Posterior compartment &#8211; Meddists<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/meddists.com\/learn\/pre-clinical\/anatomy\/lower-limb\/leg\/leg-muscles\/posterior-compartment\/\" \/>\n<meta name=\"twitter:label1\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data1\" content=\"5 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/pre-clinical\\\/anatomy\\\/lower-limb\\\/leg\\\/leg-muscles\\\/posterior-compartment\\\/\",\"url\":\"https:\\\/\\\/meddists.com\\\/learn\\\/pre-clinical\\\/anatomy\\\/lower-limb\\\/leg\\\/leg-muscles\\\/posterior-compartment\\\/\",\"name\":\"Posterior compartment &#8211; 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