Your foot is one incredibly complex structure. It has to be, based on the multiple tasks it’s expected to perform each day. While your feet help with absorbing shock, providing balance and stabilizing you on uneven surfaces, their two main functions are to support your body weight and serve as a lever to propel your body forward. None of the foot’s functions would be possible without the numerous components that make it all happen.
You can get a good idea of the foot’s complexity by reviewing its many components. Each foot contains:
- 26 Bones (plus two tiny sesamoid bones)
- 32 Joints
- More than 100 muscles, tendons and ligaments
- Skin, soft tissue and a network of nerves and blood vessels
Bones
Perhaps the easiest way to look at the anatomy of the foot is to start with the bones, breaking them down into sections that make up the three main areas of the foot. These areas are the forefoot, the midfoot and the hindfoot.
- Forefoot: The forefoot is where you’ll find your toes, also called digits, and the front portion of your foot. Your toes are made up of phalanges; the big toe has two phalanges and your other four toes each have three phalanges. Your phalanges connect to long bones known as metatarsals. You have five metatarsals, one connected to each toe.
- Midfoot: The midfoot is the area directly behind the metatarsals. It contains three cuneiform bones, one cuboid and one navicular bone. The three cuneiform bones line up at the base of your first, second and third metatarsals. The cuboid sits at the base of your third and fourth metatarsals. The navicular bone nestles neatly behind the three cuneiform bones, in front of your heel bone.
- Hindfoot: Your hindfoot contains your ankle and heel bone, officially known as your talus and calcaneus. The talus is your foot’s uppermost bone, serving as a connection point between your foot and your leg. Your calcaneus is your foot’s largest bone.
Joints
The 32 joints in your foot are made up of gliding joints, condyloid and hinge joints. Gliding joints, such as most of those in your hindfoot, allow small, gliding movements. Condyloid joints, such as those in your forefoot and toes, allow for flexion, extension, adduction, abduction and circumduction.
Hinge joints, such as your ankle, allow for flexion and extension. Your foot’s joints provide stable weight support, help you adapt to uneven ground, and allow you to spring away from the ground as you’re walking or running.
Muscles, Tendons and Ligaments
Numerous muscles, tendons and ligaments form a network throughout your foot, with the tendons connecting bone to muscle and the ligaments connecting bone to other bones. Three layers of ligaments help bind the foot bones together, assisted by the tendons of the foot muscles.
Your foot contains both extrinsic and intrinsic muscles. Extrinsic muscles are those that originate on the leg. Intrinsic muscles originate on the tarsal bones, or the seven bones of your midfoot and hindfoot. In addition to the muscles found throughout the top area of your foot, the sole of your foot contains a protective layer of deep fascia as well as four layers of muscle.
The complexity continues with your foot’s network of nerves, blood vessels and soft tissues, all packaged in place by your skin. The complexity of your foot is a blessing that ensures it can perform its weighty tasks, but it can also be a curse if something goes wrong. Because so many components are expected to seamlessly work together, even the smallest issue with one of them may eventually erupt into larger problems for the whole.
REFERENCES:
- Gibbs RC, Boxer MC. Abnormal biomechanics of feet and their cause of hyperkeratosis. J Am Acad Dematol.1982;6:1061-1069.
- Hansen JT. Netter’s Clinical Anatomy. 3rd Philadelphia, PA: Elsevier Saunders; 2014.
- Lippert L. Clinical Kinesiology and Anatom 5th ed. Philadelphia, PA: F. A. Davis Company; 2011.
- Logan BM. McMinn’s Color Atlas of Foot and Ankle Anatomy. 4th Philadelphia, PA: Elsevier Saunders; 2012.
- Wright WG, Ivanenko P, Gurfinkel VS. Foot anatomy specialization for postural sensation and control. J Neurophysiol. 2012;107(5):1513-1521.