The human foot is an very complex biomechanical structure.
It comprises of 26 bones and functions to provide, – 1) A static structural support base for weight applied upon it (via the human leg above).
2) The foot behaving as a flexible landing framework (the heel contact phase).
3) The foot behaving as a more stable propulsive framework.
The forces applied upon the foot are often many times the natural weight of the human body during foot propulsion (the heel lift phase of gait).
The common foot can be segmented into three parts:
1) The tarsal bones (of which there are 7 of the 26 bones).
2) The metatarsal bones (of which there are 5 of the 26 bones).
3) The phalanges ( of which there are 14 of the 26 bones).
Aside from the primary 26 bones, there are 2 sesamoid bones in each foot. These 2 sesamoid bones (which are located under the head of the first metatarsal bone in the forefoot) assist in flexion functionality of the forefoot.
The calcaneus is the largest (in physical size) of the tarsal bones. It is better known as the heel of the foot. It is the first of all of the 26 to bear the weight of the body as the heel makes contact with the ground. The calcaneus bone protrudes slightly at the back of the foot and there it attaches to the Achilles tendon. This strong tendon is the fibrous extension of the “Triceps Surae muscles” (or better known as the calf of the leg). Contraction of the triceps causes the Achilles tendon to act with a plantarflexion effect on the foot. Plantarflexion of the foot would best be described as heel lift and it commonly occurs just after full foot contact phase of the gait cycle.
The foot is the least understood of all moving body parts because of the complex interworking between its many joints, tendons, nerves and more. What we do know is that the foot is perfectly built for its two most important functions: (1) absorbing shock and (2) propulsion. These functions are first controlled by the brain and spinal cord that receive messages from thousands of nerve endings on sole of the foot. Nerves relay vital information about the ground terrain so the body can react accordingly. When the foot’s sensing system is synchronized with its moving hardware the foot becomes an unbeatable, self-sufficient and adaptable machine.
The videos below outline the basics of bone & mucle anatomical function..