Muscles: Going Deeper: Anatomy of Knees, Lower Legs & Feet

1) Calf Muscles

• These are on the lower leg, posterior (back) side.
• They include the gastrocnemius (a two-headed muscle) and soleus.
• The gastroc attaches to the back of the heel via the Achilles tendon.

The two heads of the gastrocnemius attach on the posterior surface of the femoral condyles (thigh bone) and the posterior surface of the calcaneus (heel bone), via the Achilles tendon. Every time you roll over the balls of your feet in your gait cycle or you flex your knee, you ignite the gastrocnemius. – Emilie Mikulla

2) Lateral Muscles

• These are on the lateral (outer) side of the lower leg.
• They include the peroneus longus and peroneus brevis.
• The peroneus longus, as its name implies, is a long muscle. It runs down the outside of the calf to the outer ankle. From there its tendon weaves under the sole of the foot and attaches in two places at the inner arch.
• The peroneus longus is the antagonist to the tibilias posterior and it works with the peroneus brevis to evert (pronate) the foot.
• The peroneus longus is a major contributor to stabilizing the foot and helps to “maintain the transverse arch of the foot, as well lift the inner and outer arches. These actions, when combined in a mindful and balanced manner, allow the leg to steady itself on top of the foot, particularly in one-legged balancing poses.” (Jenni Tarma)

3) Foot Extensors

• These muscles layer together on the anterior (inner) leg and upper part of the foot.
• They include the tibialis anterior, extensor digitorum longus and extensor hallucis longus.

4) Foot Flexors

• These muscles are deeper than the gastroc and soleus on the posterior leg.
• They include the tibialis posterior, flexor digitorum longus and flexor hallucis longus.
• The primary action of the tibilias posterior is to invert (supinate) the foot. “It is an important stabilizer of the midfoot during the ‘heel off’ phase of walking.” (Ray Long, MD)