Muscles of the Foot and Leg
Muscles on the Bottom of the Foot:
There are four layers of muscles on the bottom of the foot. The First Layer, the most superficial layer, which lies beneath a thick band of fibrous connective tissue called fascia, has three muscles: On the medial side (the side the big toe is on), there's the Abductor Hallucis Muscle stabilizes the big toe by pulling it away from the second toe. The Flexor Digitorum Brevis Muscle lies in the central portion of the foot, and it helps pull the toes down, a motion called plantarflexion. On the outside (lateral portion) of the foot lies the Abductor Digiti Minimi Muscle. This muscle stabilizes the little toe by pulling it away from the fourth toe.
The Second Layer of muscles consists of the Quadratus Plantae Muscle, which attaches to and redirects the pull of the Flexor Digitorum Longus tendon coming down from the leg. This helps pull the four small toes down against the ground (plantarflexes them). This layer also contains three small muscles called the Lumbricales. The lumbricale muscles actually have a somewhat complicated function for such small muscles. They help pull the toe down against the floor at the joint where the toes attach to the foot, yet help extend (or raise up) the toes at the next joint. Basically, they help balance the effects of the large muscles that pull the toes up and down. The word 'Lumbricale' means 'earthworm' in Latin, a reference to the small, narrow appearance of the muscle.
The Third Layer of muscles has three more muscles: The Flexor Hallucis Brevis Muscle helps pull the big toe down (plantarflexes it) against the ground. The Adductor Hallucis Muscle helps stabilize the big toe by pulling it towards the second toe. (It counters the pull of the Abductor Hallucis Muscle described above.) The Flexor Digitorum Brevis Muscle pulls the four small toes down against the ground (plantarflexes them).
The Fourth Layer
of muscles consists of four Dorsal
Interosseous Muscles and three Plantar
Interosseous Muscles. These stabilize the
small toes so they don't drift towards or away from the adjacent toes.
Muscles on the Top of the Foot:
While the bottom of the foot has seventeen muscles, the top of the foot only has one. The Extensor Digitorum Brevis Muscle attaches to the top of the foot to help dorsiflex (lift up) the toes.
Muscles of the Leg that Attach into the Foot:
In addition to the small muscles of the foot described above, there are quite a few muscles that attach into the foot from the leg.
On the front of the leg lies the Anterior Muscle Group. The Tibialis Anterior Muscle helps lift the foot against the ankle (Dorsiflexes it) and inverts it (pulls the sole of the foot so that it faces the opposite foot). The Peroneus Tertius Muscle helps lift the foot against the ankle, and it everts it (pulls the sole of the foot so that it faces away from the opposite foot. The Extensor Hallucis Longus Muscle helps raise the big toe up (dorsiflexes it). The Extensor Digitorum Longus Muscle helps raise the small toes up (dorsiflexes them).
The muscles on the outside of the leg (the Lateral Muscle Group) consists of the Peroneus Longus and Peroneus Brevis Muscles. These muscles pull the foot down (plantarflexes it) and pull the sole of the foot away from the opposite leg. The Peroneus Longus also has the effect of stabilizing the first metatarsal bone.
The Posterior Muscle Group is divided into two sections. The superficial group consists of the Gastrocnemius, Soleus and Plantaris muscles (the calf muscles), which come together to form the Achilles tendon. This tendon pulls the foot down, like you'd move the foot if you pushed down on the gas pedal in your car. The deep group consists of the Flexor Hallucis Longus Muscle, which pulls the big toe down against the ground (plantarflexes it), and the Flexor Digitorum Longus Muscle, which splits into several small tendons that attach into the smaller toes to pull the small toes down against the ground (plantarflexes them).