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Understanding Foot Anatomy
Did you know each foot is made up of 28 bones, 30 joints and more than 100 muscles, tendons and ligaments? Here's a look at the main structures of the feet.
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- Talus: The talus forms the lower part of the ankle joint through its articulations with the tibia and fibula. Through the talocalcaneonavicular joint, it transmits the entire weight of the body to the foot anteriorly toward the toes.
- Calcaneus: The calcaneus is the largest of the tarsal bones and is the weight-bearing bone within the heel of the foot.
- Tibia: The tibia is one of the bones located between the knee and ankle. It is the inner bone next to the fibula and often is larger than the fibula.
- Fibula: The fibula is the other bone that is located between the knee and ankle. It is the outer bone next to the tibia and often is smaller than the tibia.
- Tarsals: The tarsals are a group of seven articulating bones in the ankle.
- Metatarsals: The metatarsal bones are a group of five long bones in the foot, located between the tarsal bones and the phalanges. These bones form the sole of the foot and are numbered from the medial side.
- Phalanges: The distal phalanges are the bones at the tips of the toes. The proximal phalanges are long bones that make up the digits of the hands and feet. The proximal phalanges are those that are closest to the hand or foot. The intermediate phalanges are not only intermediate in location, but usually also in size. The large toe does not possess a middle phalanx.
- Sesamoids: Sesamoids are very small circular bones that are found under the first metatarsal.
- Metatarsophalangeal Joint (MTP): The metatarsophalangeal joint connects your toes to the metatarsal bones in your foot. The is an MTP joint for each of your toes.
- Proximal Interphalangeal Joint (PIP): joints that are located between the proximal phalanges and medial phalanges.
- Distal Phalangeal Joint (DP): joint that is located between the medial and distal phalanges.
*Each big toe has a metatarsophalangeal joint and an interphalangeal joint.
- Tibilias Posterior: located in the posteriorly to the tibia and fibula and is the most central and deepest posterior muscle. It helps with plantar flexion within the foot and supports the arch.
- Tibilias Anterior: located on the lateral side of the tibia, mostly near the shin bone. It works to move the foot up and down (invert).
- Tibilias Peroneal: located on the lateral side of your leg and allows you to move your ankle in addition to stabilizing it.
- Extensors: Works with other muscles in order to dorsiflex and invert the foot (and toes). The extensor digitorum longus extends the foot and the extensor hallucis longus extends the toes.
- Flexors: Flexor hallucis brevis and adductor hallucis control the movements of the big toes and are located on the medial side of the foot.
Tendons and Ligaments
- Achilles Tendon: Also known as the calcaneal tendon, this is the thickest tendon in the human body. It serves to attach the plantaris, gastrocnemius and soleus muscles to the calcaneus bone. The muscles, acting via the tendon, cause plantar flexion of the foot at the ankle, and flexion at the knee.
- Plantar Fascia: Plantar Fascia is located on the underside of the foot and connects the calcaneus with the heads of the metatarsal bones. Along with the plantar calcaneonavicular ligament, the plantar fascia helps stabilize the arch of the foot.
- Plantar Calcaneonavicular Ligament: The plantar calcaneonavicular ligament (spring ligament) is a complex of three ligaments on the underside of the foot that connect the calcaneus with the navicular bone. The plantar calcaneonavicular ligament stabilizes the arch of the foot.
- Calcaneocuboid Ligament: It is located on the underside of the foot and connects the calcaneus with the cuboid bone. Along with the plantar calcaneonavicular ligament, the calcaneocuboid ligament aids in strengthening the foot and facilitates movement.