Muscles of the Leg
The muscles of the leg play an important role in the movement of the lower body, and are divided into the anterior, lateral and posterior compartments. This article looks at the major muscles in each of these compartments, outlining their position, origin, insertion and action.
Muscles in the Anterior Compartment of the Leg
- The tibialis anterior is a long, thin muscle located on the anterior aspect of the leg and extending down to the ankle. It is the largest muscle in the anterior compartment and is responsible for dorsiflexion of the foot and inversion of the foot at the ankle. It originates from the lateral condyle of the tibia and inserts onto the medial cuneiform and first metatarsal bones of the foot.
- The extensor digitorum longus is situated medial to the tibialis anterior, and originates from the lateral condyle of the tibia. It’s muscle fibers extend distally, inserting into the extensor expansion of the second, third, fourth and fifth digits. It is primarily responsible for dorsiflexion of the foot and extension of the toes.
- The fibularis longus is a small muscle located lateral to the tibialis anterior, extending distally to insert onto the fifth metatarsal bone of the foot. It is responsible for dorsiflexion of the foot and eversion of the ankle.
- The fibularis brevis is located deeper than the fibularis longus and is largely responsible for eversion of the foot and plantar flexion of the ankle.
Muscles in the Lateral Compartment of the Leg
- The peroneus longus is a flat, tendonous muscle located on the lateral aspect of the leg, originating from the head of the fibula and inserting onto the first metatarsal bone and the medial cuneiform of the foot. It is responsible for eversion of the ankle and plantarflexion of the foot.
- The peroneus brevis is located deep to the peroneus longus, and originates from the head and neck of the fibula and inserts onto the fifth metatarsal bone. It is responsible for eversion of the ankle and plantarflexion of the foot.
- The extensor hallucis longus is located deep to the peroneus brevis, and originates from the fibula. It inserts onto the base of the distal phalanx of the great toe and is the primary muscle responsible for plantarflexion of the foot and extension of the great toe.
Muscles in the Posterior Compartment of the Leg
- The gastrocnemius is the largest muscle in the posterior compartment, located between the knee and the ankle. It is a two-headed muscle composed of medial and lateral heads, originating from the medial and lateral condyles of the femur respectively. It inserts onto the calcaneus via the Achilles tendon and is responsible for plantarflexion of the foot.
- The soleus is located deep to the gastrocnemius, originating from the fibula, tibia and soleal line of the tibia. It inserts into the Achilles tendon and is largely responsible for plantarflexion of the ankle and stabilisation of the ankle, but may also assist in the plantarflexion of the entire foot.
- The plantaris is a thin, long muscle located deep to the soleus, and originates from the lateral supracondylar line of the femur. It inserts into the Achilles tendon and is largely responsible for plantarflexion of the entire foot.
The muscles of the leg play a crucial role in the movement of the lower limbs, by providing power for walking, running and other locomotor functions. In order to ensure that these muscles are able to function effectively, it is important to understand their position, origin, insertion and action. This article has provided an overview of the major muscles in the anterior, lateral and posteior compartments of the leg, and highlighted the key functions of each muscle.
