What Muscles Make up Your Achilles Tendon?

A tendon is a band of fibrous tissue that connects muscle and bone. The Achilles tendon, otherwise known as the calcaneal tendon or the tendocalcaneus, is located in the back of your lower leg and connects your calf muscles to your heel. Almost 6 inches in length, this tendon is the strongest tendon in the human body. It is especially prone to injury because it receives minimal oxygen and nutrients from the circulatory system.

Gastrocnemius

• One of two major calf muscles, the gastrocnemius has two large heads that originate at the bottom of the femur. This muscle flexes the ankle when the knee is straight. At the mid-point of the calf, this muscle connects to the tendon of the gastrocnemius.

Soleus

• The soleus muscle flexes the ankle when the knee is bent. This muscle lies under the gastrocnemius. Beginning in the middle of the calf, some soleus muscle fibers connect with the tendon of the gastrocnemius. When the tendons of the two calf muscles combine in the lower calf, they are called the Achilles tendon.

Attachment to Bone

• The Achilles tendon attaches to the calcaneus. This bone, located at the back of the foot, is colloquially known as the heel bone.

Protection of the Achilles Tendon

• Unlike many other tendons, the Achilles tendon is not protected by a synovial sheath. These flat, fluid-filled sacs wrap completely around tendons and protect them from irritation and injury. Instead, the only cushioning the all-important Achilles tendon has is a set of two small fluid-filled bursa: the retro-calcaneal bursa and the subcutaneous calcaneal bursa.