The Superficial Muscles
The superficial muscles of the posterior leg include three muscles. The gastrocnemius originates in the femur and ends in the calcaneus or heal bone. It is one of the muscles responsible for flexes the foot and the knee. The plantaris also starts in the femur and ends in the calcaneus and has much the same role as the gastrocnemius. The third superficial muscle of the posterior leg is the soleus which starts along the shafts of the tibia and fibula and inserts into the calcaneus. It is responsible for powerful ankle flexion and is the main muscle involved in the force of propulsion required for walking and running.
The Deep Muscles
The deep muscles of the posterior leg include three more muscles. The flexor digitorum longus originates in the shaft of the tibia and inserts in the four smaller toes. It is responsible for the movement of the toes, flexion of the foot and support of the foot’s arch. The flexor hallucis longus begins in the shaft of the fibula and inserts near the base of the big toe and moves that toe, flexes the foot, and also aids in supporting the arch of the foot. The tibialis posterior begins in the shafts of both the fibula and tibia and inserts in the area of the navicular a smaller bone in the mid foot. It is responsible for flexing the foot, inverting the foot in the area of the mid-foot joints and supporting the arch of the foot.
Other structures of the posterior leg
The saphenous vein and the posterior tibial artery take waste away and supply blood to this area of the leg respectively. The nerves that are involved with the posterior muscles of the leg include the peroneal communicating branch of the common peroneal nerve, the medial cutaneous nerve of the calf, and the sural nerve. The nerve that acts to mainly control all of these muscles is the tibial nerve. It sends messages from the brain to these muscles in order to effect coordinated movement of the small joints of the foot, the toes, the ankle and even the knee so that the leg will work properly when standing, walking or engaging in other activity.
The muscles of the posterior leg work to move the leg, maintain the structure and integrity of the foot, move the foot, move the toes, and move the knee. These muscles of the posterior leg along with others are involved in not only the obvious movement one thinks about, but are also important in positioning the leg and foot when we stand, sit or even lie in bed to sleep.