In Depth: Muscles
The 20-plus muscles in the foot help enable movement, while also giving the foot its shape.
Like the fingers, the toes have flexor and extensor muscles that power their movement and play a large role in balance.
However, many muscles that power the foot’s movement originate as high up as the back of the knee. Some important muscles that affect the foot include:
- Soleus: This muscle extends from the back of the knee to the heel. It is pivotal in walking and standing.
- Gastrocnemius (calf muscle): One of the large muscles of the leg, it connects to the heel. It flexes and extends the foot, ankle, and knee.
- Plantaris: This small, thin muscle is absent in about five to ten percent of people. Its function is superseded by the calf muscle.
- Abductor hallucis: A muscle on the inner side of the foot that runs from the big toe to the heel, it pulls the big toe, or hallux, away from the body.
- Tibialis anterior: This muscle runs from the tibia to the first toe, and helps make walking possible by flexing the foot upward and turning it inward.
- Extensor digitorum longus: This is one of three muscles that pull the foot upward. It also extends the toes, lifts the toes, and turns the foot outward.
- Flexor digitorum longus: This muscle in the calf and foot flexes the second through fifth toes and points the toes downward.
- Fibularis longus: This muscle helps move the foot sideways as well as flex it downward, like when you push down on the gas pedal of a car.
- Fibularis tertius: This muscle helps move the foot side to side at the ankle joint.
- Fibularis brevis: This small muscle helps move the foot downward.
The muscles create motion in the body by moving the skeleton. The muscles are attached to bone by fibrous tendons.
In terms of mobility, the Achilles tendon is one of the most important structures in the leg and foot. This tendon in the back of the calf and ankle connects the plantaris, calf, and soleus muscles to the heel bone. It stores the elastic energy needed for running, jumping, and other physical activity.
Ligaments hold bones together and stabilize joints. One of the main ligaments in the foot is the plantar fascia, which forms the arch on the sole of the foot. As it stretches and contracts, the plantar fascia provides balance and strength to the foot.