It attaches to the inferior surface of the distal phalanx of the hallux. This muscle is located laterally in the posterior compartment, and originates from the fibula. It acts to flex each toe (with exception of the hallux). It originates from the medial tibia and attaches to the inferior surface of each of the four digits. This muscle is located medially in the posterior compartment. This acts to plantarflex and invert the foot. It attaches to the inferior surface of the medial tarsal bones. It is unique in that it acts to 'unlock the knee' by laterally rotate the femur on the tibia normally when standing, this locking allows for the knee to support the standing weight of a human, and so popliteus is important for unlocking the knee so knee flexion can occur.Ī large, deep muscle which originates between the tibia and fibula, via the interosseous membrane. It originates from the lateral femoral condyle and attaches just above the soleal line of the tibia. This muscle lies posterior to the knee joint. Once again, each muscle is innervated by the tibial nerve. With exception of the popliteus, it’s useful to know that tendons of the muscles in the deep posterior compartment travel posterior to the medial malleolus, allowing access to the inferior surface of the foot for attachment. In the deep posterior compartment, there is a tibialis muscle which acts to plantarflex and invert the foot, there’s a muscle for the flexion of the toes and a muscle for flexion of the big toe. Notice the similarities with the anterior compartment of leg muscles. The remaining muscles of the posterior compartment are deep. Like the other muscles, it acts to plantarflex the foot.ĭeep Muscles of the Posterior Compartment It originates from the lateral epicondyle of the femur and attaches via the calcaneal tendon. It acts to plantarflex the foot.įound just superficial to the soleus, it is a small muscle with a very long tendon. It originates from the soleal line of the tibia and attaches to the calcaneus. It can also aid knee flexion as it crosses the knee joint.Ī large, flat muscles located just deep to Gastrocnemius, Soleus gets it name from being shaped like a sole (a big flat fish). These converge to form single muscle belly, which then attaches to the calcaneus as described above. It has a medial and lateral head, which originate from the medial and lateral femoral condyles respectively. Gastrocnemius is the most superficial of the posterior leg muscles. Each of these muscles are innervated by the tibial nerve. Superficial Muscles of the Posterior CompartmentĮach superficial muscle inserts into the calcaneus of the foot via the calcaneal tendon (aka. Both layers are innervated by the tibial nerve and typically act to plantarflex the foot. The posterior compartment is slightly more complex, in that it is split into superficial and deep layers. Notice how deep the extensor hallucis longus is compared to the tibialis anterior and extensor digitorum longusĬreative commons source by OpenStax College, edited by Sachin Sudhakaran It is responsible for the extension of the hallux/big toe but also contributes to dorsiflexion of the foot.ĭiagram - Anterior compartment of muscles in the leg, highlighted. As the name suggests, these act to extend the toes, whilst also aiding dorsiflexion.Įxtensor Hallucis Longus originates from the medial fibula and inserts into the distal phalanx of the big toe. It also acts to invert the foot.Įxtensor Digitorum Longus originates from the lateral condyle of the tibia and forms four tendons, which insert into a digit (with exception of the hallux/big toe). It attaches to the medial cuneiform (one of the bones in the foot) and acts to dorsiflex the foot. Tibialis Anterior is found on the lateral surface of the tibia, where it originates. Muscles in the anterior compartment act to dorsiflex the foot and are innervated by the deep fibular nerve (a branch of the common fibular nerve). For more information, please check out our Anatomical Terminology Article. It is also very important when studying muscles that you are comfortable with anatomical terminology, as a lot is used in these articles. Whilst there are many muscles in the leg, they can be compartmentalised into anterior, lateral and p osterior fascial compartments. Muscles of the lower leg typically act at the ankle joint and are innervated by branches of the sciatic nerve.
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