JOINTS OF THE FOOT AND ANKLE:
The purpose of this article is to provide a brief overview of the major joints of the foot and ankle, describing their structure and function. There are 28 bones and 33 joints in the foot and ankle. Some function to support the weight of our bodies, while others are designed to disperse that weight and move us forward. The foot is relatively stable because there is little free movement between the bones of the foot. The foot must absorb the shock of the body weight every time we take a step.
Because there are so many small bones in the foot, and many of them articulate with more than one bone, the names of these joints can get quite confusing. To add to the confusion, different books will call the joints different names. I have tried to include as many of the different names as possible. I recommend reading this article with an open anatomy book, a picture is worth a thousand words.
TALOCRURAL JOINT:
This joint is made by the articulation between the talus and the distal tibia and fibula. It's also called the mortise joint, due to its strong resemblance to a mortise joint in woodworking. This joint is responsible for most of the plantarflexion/dorsiflexion of the foot, and bears 100% of the weight of the body before dispersing it into the remainder of the foot.
SUBTALOR JOINT:
Also called the talocalcaneal joint, this joint is formed by the articulation between talus and calcaneus. The talus sits on the anterior two-thirds of the calcaneus. Through a combination of movements, the subtalor joint provides inversion/eversion of the ankle joint. When standing, the ground restricts the movement of the calcaneus, so subtalor joint motion is critical when weight bearing.
TRANSVERSE TARSAL JOINTS:
Also called the midtarsal joints, there are a lot of different joints in this category. Basically, the midtarsal joints are the transitional link between the hindfoot and the forefoot. This area adds to the motion of the calcaneus (inversion/eversion), and helps the foot transition from weight-bearing to walking. The tarsal joint is very important in the early stance phase of gait. It is the talus and calcaneus articulating with the navicular and cuboid bones, so there are many different names for the joints in this area.
NAVICULAR JOINT:
The bones that articulate with the navicular form many joints. It is easier to look at the function of these joints as a whole, rather than specify each individual joint. The navicular bone is at the top of the arch of your foot. This area participates in both hindfoot motion and in midfoot motion. It's two faced - it articulates the talus and calcaneus so on that side it helps inversion/eversion, and articulates with the mid foot which adds to dorsi/plantar flexion.
TARSOMETATARSAL JOINTS:
Tarsometatarsal joint function is a continuation of the transverse tarsal joint - they regulate position of the metatarsals and phalanges (toes) relative to the ground.
METATARSOPHALANGEAL JOINTS:
These joints make up the balls of your feet. It is where the long bones of your feet (metatarsals) and your toes (phalanges) meet. These joints allow flexion/extension of the toes. When the heel leaves the ground, these joints distribute your weight evenly across the ball of the foot, providing a smooth transition of weight onto the toes.
INTERPHALANGEAL JOINTS:
The toes function to smooth the weight shift to the opposite foot in gait and help maintain stability by pressing against the ground both when standing and walking.
The foot and ankle are very complex structures, working as a unit to support the weight of our bodies, while providing an amazing amount of movement and stability. The more we understand about the bones and joints of the foot, the more we can appreciate what they do.
