Foot Muscle/Tendon/Ligament Function

There are many important muscles, tendons and ligaments in the foot. It’s important to understand their function. When you understand their function, you can understand the reason they become injured.

In this post, we dive into the details of what the function of the major muscles/tendons/ligaments are in the foot.

The Abductor Digiti Minimi  

The abductor digiti minimi is a muscle located in the outside of the foot. Its primary function is to abduct the little toe, or move it away from the midline of the body. The abductor digiti minimi muscle is used when walking, running, and standing. It helps to stabilize the foot.

The Abductor Hallucis Muscle 

The abductor hallucis muscle is a long, thin muscle located on the medial (inner) aspect of the foot. It originates at the heel bone (calcaneus) and inserts at the base of the big toe (hallux). The muscle acts to abduct (move away from the midline of the body) and flex (bend) the big toe.

The Achilles Tendon

The Achilles tendon is a thick, fibrous band of tissue that connects the calf muscle to the heel bone. It is the strongest and thickest tendon in the human body. The Achilles tendon is used when walking, running, jumping, and climbing. It helps to raise the heel off the ground when walking and provides power when pushing off with the foot while running.

The Adductor Hallucis Muscle 

The adductor hallucis muscle is a muscle located in the foot. It is a long, thin muscle that runs along the inside of the foot. This muscle is responsible for the movement of the big toe. 

The adductor hallucis muscle has two main functions. The first function of this muscle is that it pulls the metatarsal heads together. The second function is that it aids in adduction and plantarflexion of the big toe.

The Anterior Tibial Tendon

The anterior tibial tendon is one of the major tendons in the leg. It starts in the leg and attaches along the inside of the foot. It helps raise the foot and also inverts and adducts the foot. The anterior tibial tendon is an important structure in the leg that helps with walking and running. The tendon can become injured from overuse or trauma and symptoms include pain, swelling, and tenderness in the leg or foot.

The Dorsal Interossei Muscles

The dorsal interossei muscles are a group of muscles located in the foot. There are four dorsal interossei muscles on each foot, and they are located between the metatarsals (long bones in the foot). These muscles function to extend (straighten) the digits (toes) and also to assist with abduction (moving away from the midline) of digits two, three, and four.

The Extensor Digitorum Longus Tendon

The extensor digitorum longus tendon starts in the tibia and fibula and extends into the top of the toes. The extensor digitorum longus  tendon lifts up the lesser toes and the foot. It is used when walking and running. 

The EDL tendon can be injured in a variety of ways. These injuries can occur due to overuse, direct trauma, or repetitive stress. Overuse injuries usually happen when there is too much strain on the tendon from activities such as running or jumping.

Direct trauma injuries can occur from a fall or direct blow to the leg. Repetitive stress injuries happen when there is repetitive motion of the foot and ankle, which can cause inflammation of the tendon.

The Extensor Hallucis Longus Tendon

The extensor hallucis longus tendon is a long, slender tendon that is responsible for extending the big toe. The EHL tendon attaches the EHL muscle to the big toe and helps to stabilize it. The EHL muscle is used when walking, running, and climbing. It is also used when standing on your toes or when wearing high heels. It is an important stabilizer of the big toe.

The Flexor Digitorum Longus Tendon

The flexor digitorum longus tendon is a tendon located in the lower leg. The flexor digitorum longus tendon originates in the back of the tibia and inserts into the bottom of the toes. It acts to plantarflex the foot and the toes. This action is important in activities such as walking and running.

The Flexor Hallucis Longus Tendon

The flexor hallucis longus tendon originates in the back of the fibula and inserts to the bottom of the big toe. The function of the flexor hallucis longus tendon is to flex, or bend, the big toe.  It also helps with foot plantarflexion.

The Lumbrical Muscles

The lumbrical muscles are a group of four muscles located in the foot. They originate in the foot along the flexor digitorum longus tendons and insert into the foot near the toes. 

The function of lumbrical muscles is two-fold. First, these muscles help to flex the toes. This is achieved by contracting and pulling on the tendons to which they are attached. Second, the lumbricals stabilize the foot during locomotion by keeping the metatarsals in alignment. This prevents slippage and injury.

The Peroneal Tendons

Peroneus Longus Function

The peroneus longus is the muscle that everts (turns out) the foot at the ankle. It also helps to stabilize the ankle when walking on uneven surfaces. This muscle is located on the outside of the lower leg and attaches to the fibula (the smaller bone in the lower leg). It runs behind the lateral malleolus (the bony protrusion on the outside of the ankle) and under the foot to attach to the base of 1st metatarsal.

Peroneus Brevis Function

The peroneus brevis is located on the outside of the lower leg, just below the peroneus longus. It attaches to the fibula and runs behind the lateral malleolus to attach to the fifth metatarsal base. 

The peroneal tendons help stabilize the foot and ankle. These tendons can be injured due to overuse or trauma.

The Plantar Interossei 

There are three plantar interossei muscles in each foot.  They originate along the metatarsals and insert into the toes. The plantar interossei muscles aid to adduct the third, fourth and fifth toes. These muscles work together to provide stability and balance while walking and running, absorb shock during impact activities, and assist in push-off during the toe-off phase of gait. 

The Posterior Tibial Tendon

The posterior tibial tendon is one of the most important tendons in the human body. The posterior tibial muscle originates in the back of the tibia and fibula, and goes on to insert in the navicular, first-third cuneiforms, the cuboid, and second-fourth metatarsal bases. This tendon functions to help with plantarflexion and supination of the foot. 

The posterior tibial tendon plays a vital role in supporting the arch of your foot and helping you to walk and run correctly. Without this important tendon, you would be unable to stand on your toes.

The Anterior Talofibular Ligament

The anterior talofibular ligament (ATFL) is a ligament located in the ankle. It connects the talus (a bone in the ankle) to the fibula (a bone in the lower leg). The ATFL stabilizes the ankle joint and resist inversion stresses to the ankle. 

ATFL injuries most commonly occur during sports that involve lateral (sideways) movements, such as basketball, soccer, and football. These injuries can also occur as a result of a fall or direct blow to the outside of the ankle.

The Calcaneofibular Ligament

The calcaneofibular ligament (CFL) is one of three ligaments that stabilize the ankle joint. It is located on the outside (lateral) aspect of the ankle and attaches the calcaneus (heel bone) to the fibula (one of the two bones in the lower leg). The CFL functions to provide the ankle and subtalar joint with stability.

The Posterior Talofibular Ligament

The posterior talofibular ligament (PTFL) is a strong fibrous band that runs from the back of the talus (ankle bone) to the outer side of the fibula (calf bone). It helps to stabilize the ankle joint by preventing talar external rotation.

The Syndesmosis Ligament of the Ankle

The ankle syndesmosis ligament is a key ligament in the stability of the ankle. This ligament spans from the tibia to the fibula, connecting these two bones. It is important in weight bearing and stabilizing the ankle during movement.

The Deltoid Ligament of the Ankle

The superficial deltoid ligament is made up of three parts: the tibionavicular, tibiocalcaneal, and superficial posterior tibiotalar ligaments. 

The deep deltoid is made up of two parts: the anterior talotibial ligament and the deep posterior talotibial ligament. 

The deltoid ligaments aid to prevent lateral displacement of the talus. In other words, it prevents the ankle from moving away from the body. The deltoid ligament is strong and helps stabilize the ankle joint.

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