Leg (knee to ankle) - superficial posterior view
View the surface muscles of the leg from the back. See where the soleus and gastrocnemius muscles — commonly known as the calf muscles — are. The calf muscles are essential to pushing off from the ground and standing on your toes.
The calf muscles
The gastrocnemius, soleus and plantaris muscles are known as the calf muscles. They form the superficial muscles of the posterior compartment of the leg. The deep muscles of the posterior compartment of the leg are the popliteus, tibialis posterior, flexor digitorum longus and flexor hallucis longus.
The gastrocnemius calf muscle is the most superficial of the calf muscles. It inserts onto the heel bone via the Achilles tendon. The gastrocnemius muscle flexes the foot at the ankle joint — that is it acts to point the foot downwards by bending it at the ankle joint, such as when you stand on your toes. This action is known as plantar flexion. The gastrocnemius also flexes the leg at the knee joint. It is stretched by ‘straight-leg calf stretches’.
The soleus calf muscle is deeper than the gastrocnemius. It inserts onto the heel bone along with the gastrocnemius via the Achilles tendon. The soleus muscle also plantar flexes the foot at the ankle joint. The soleus is stretched by ‘bent-leg calf stretches’.
The plantaris muscle is a small muscle that runs between the soleus and gastrocnemius muscles — in some people it is missing. The plantaris tendon comes off the plantaris muscle and inserts into the heel bone via the Achilles tendon, along with the other 2 calf muscles. It plantar flexes the foot at the ankle joint and also flexes the leg at the knee joint.
The Achilles tendon
The Achilles tendon connects your calf muscles to the back of your heel bone — the calcaneus. It is the largest tendon in your body. It allows extension of your foot downward, away from your body, which lets your heel lift off the ground as you move forward when walking. Every time you take a step you rely on your Achilles tendon.
If the Achilles tendon is ruptured, a person may feel a sudden sharp pain at the back of their calf — like being shot, sometimes accompanied by a loud pop or snapping noise. The tendon may be torn completely or partially torn.
The flexor retinaculum is a ligament — a strong band of fibrous tissue — that holds down the tendons of the foot. Sometimes the posterior tibial nerve can be compressed as it passes under the flexor retinaculum, causing a condition known as tarsal tunnel syndrome.
The lateral malleolus is the bony prominence that we know as our outer ankle bone. It is actually part of the leg bone called the fibula.
The medial malleolus is the bony prominence on the inside of our foot that we also may call our ankle bone. It is part of the leg bone called the tibia.
2. MayoClinic.com. Slide show: A guide to 10 basic stretches (updated 23 Feb 2011). http://www.mayoclinic.com/health/stretching/SM00043 (accessed Apr 2013).
3. American Academy of Orthopedic Surgeons (AAOS). Achilles tendinitis (updated June 2010). http://orthoinfo.aaos.org/topic.cfm?topic=a00147 (accessed Apr 2013).
4. Merck Manual Home Health Handbook. Tarsal tunnel syndrome (updated Dec 2012). http://www.merckmanuals.com/home/bone_joint_and_muscle_disorders/foot_problems/tarsal_tunnel_syndrome.html (accessed Apr 2013).