Foot – Bones, Ligaments, Muscles & Conditions
The foot is responsible for supporting the weight of the body, while enabling us to walk, run, and move smoothly with speed and precision. The foot is made up of bones, joints, muscles, and soft tissue like ligaments and tendons.
Bone and Joint
There are 28 bones in the foot, and over 30 joints. The bones in the foot include the five toe bones, called phalanges; five metatarsal bones in the body of the foot; three cuneiform bones, the cuboid bone and the navicular bone, which make up the arch of the foot; the calcaneus, or heel bone, which is the largest bone in the foot; and the talus bone, which supports the leg bones (tibia and fibula) where they form the ankle joint.
The ankle joint, called the tibiotalar joint is formed where the tibia meets the talus bone. Other joints in the back of the foot include the subtalar or talocalcaneal joint where the talus bone connects to the calcaneus, the talonavicular joint where the talus connects to the navicular bone, and the calcaneocuboid joint where the calcaneus meets the cuboid bone.
In the mid-foot are the metatarsocunieform joints, where the metatarsals meet the cuneiform bones. The metatarsophalangeal joints occur where the metatarsal bones meet the phalanges. The big toe joint, or first metatarsophalangeal joint can be prone to arthritis and it typically where bunions develop.
Common bone and joint conditions of the foot include: Fat Fleet (Pes Planus), Toe Fracture, Foot Fracture, Metatarsal Fracture, Bunions, Stress Fracture, Heel Spur, Fracture of the Talus, Club Foot, lisfranc fracture (fracture of midfoot) and Arthritis.
There are more than 30 muscles that attach to or affect the foot. They provide strength and stability, giving the foot its shape, keeping the bones in the proper position and providing energy to propel the foot and help it move. There are four plantar (sole) muscles layers. The first layer includes the adductor hallucis, the flexor digitorum brevis, and the abductor digiti minimi. The second layer includes the lumbricals, the third layer is made up of the flexor hallucis brevis, the adductor hallucis, and the flexor digiti minimi brevis, and the fourth layer is made of the interossei muscles.
There are four dorsal interossei muscles, which are located between the metatarsal bones. Each muscle is bipenniform, meaning it has two places where it attaches. There are also three plantar interossei muscles that are found beneath the metatarsal bones. These muscles have one point of attachment.
The extensor muscles, including the extensor digitorum brevis, the extensor digitorum longus, and the extensor hallucis longus help to raise or extend the toes to assist in the movement needed to step forward. The flexor muscles, including the flexor digiti minimi brevis, the flexor digitorum brevis, the flexor hallucis brevis, and the flexor hallucis longus help flex or bend the toes.
Other muscles that act within the foot include the peroneous brevis, which is located on the outside of the lower leg and travels from the fibula to the metatarsal bone of the little toe; the peroneus tertius, which is located against the peroneus brevis, and the peroneus longus which originates at the fibula and descends to the calcaneus, and inserts at the base of the metatarsal of the big toe.
The major muscles of the ankle include the gastrocnemius and soleus (calf) muscles, which push the foot down and allow us to go up on our toes. These two large muscles join at the ankle at the calcaneus or heel to form the Achilles tendon. The foot also serves as the attachment for the tibialis anterior, and the tibialis posterior.
A tendon is part of the muscle that attaches muscle to bone. Tendons are strong, fibrous tissues that are responsible for transferring the forces generated by the muscle to the bone, thus producing movement at the joint. When a tendon becomes irritated or inflamed it becomes painful, especially with movement. Inflammation of the tendon is called tendonitis.
The Achilles tendon is another important structure in the foot and ankle that makes it possible to run, walk, and jump. The Achilles tendon attaches the calf muscles, through the ankle joint, to the calcaenous (heel bone.) The anterior tibial tendon and the posterior tibial tendon also help support and move the foot.
Common conditions of the muscles and tendons of the foot include: Achilles Tendonitis, Achilles Tendon Rupture, Peroneal Tendonitis, Post Tibial Tendonitis and Turf Toe.
Ligaments are soft tissues made of collagen and attach bone to bone. On the outside (lateral) side of the ankle there are three major ligaments, there are several more ligaments on the inside (medial) side of the ankle joint. Ligaments in the foot include the plantar calcaneonavicular ligament, the deltoid ligament, the long plantar ligament, and the plantar calcaneocuboid.
The plantar fascia is a thick connective tissue in the foot that runs from the calcaneus or heel bone to the metatarsal heads at the base of the toes. The plantar fascia is found in the sole of the foot, and helps to support the arch of the foot. The plantar fascia can become inflamed, causing a condition known as plantar fasciitis – a common cause of foot pain.
Common muscle conditions of the foot include: Foot Sprain, Plantar Fasciitis, and Ankle Sprain, Flat Feet (Pes Planus)
A burse is a fluid filled sac that decreases friction between two tissues. Bursa in the ankle include the retrocalcaneal bursa, the subcutaneous burse of the medial malleolus, and the subcutaneous calcaneal bursa. Bursa in the foot include the metatarsal bursa, intermetatarsal bursa, the metatarsophalangeal bursa, and the calcaneal bursa.
Common conditions of the burse of the foot include: Calcaneal Bursitis, Metatarsal Bursitis, Intermetatarsal Bursitis, Metatarsophalangeal Bursitis.
There are five major nerves of the lower leg that affect the foot. These nerves provide both sensation and motor control of to the foot.
- Sural Nerve which branches and supplies sensation to the outer part of the foot and little toe.
- Saphenous Nerve which supplies the sensation to the inner aspect of the foot.
- Posterior Tibial Nerve, which passes behind the medial malleolus and divides into three branches. The medial calcaneal branch supplies sensation to the calcaneus or heel while the two medial plantar nerves and lateral plantar nerves branches supply sensation to the bottom of the foot and toes as well as motor innervation.
- Deep Peroneal Nerve supplies sensation to the top of the foot and motor innervation to the extensor muscles of the foot and toes which help to lift the foot up.
- Superficial Peroneal Nerve supplies motor innervation for the peroneal muscles of the foot and sensory innervation of the top of the foot.
Common conditions of the foot include Tarsal Tunnel Syndrome, Drop Foot, Neuroma of the Foot (Morton’s Neuroma), Neuropathy of the foot.