The tarsal bones are a group of irregularly shaped bones in each foot that form a foundational structure. They play a significant role in enabling various movements and supporting the body’s weight. These bones contribute to the complex architecture of the foot, designed for both stability and flexibility.
Where Tarsal Bones Are Found
The tarsal bones are situated in the posterior aspect of the foot, forming the ankle and upper part of the foot. There are seven such bones in each foot, collectively known as the tarsus. They are positioned between the tibia and fibula of the lower leg and the metatarsal bones leading to the toes.
These bones are arranged in two main groups: the hindfoot and the midfoot. The hindfoot comprises the talus and calcaneus, forming the framework around the ankle and heel. The midfoot includes the navicular, cuboid, and the three cuneiform bones.
The Seven Tarsal Bones
These bones include the calcaneus, talus, navicular, cuboid, and the medial, intermediate, and lateral cuneiforms.
The calcaneus, commonly known as the heel bone, is the largest of the tarsal bones and forms the prominence at the back of the foot. It lies underneath the talus and supports body weight during heel strike, also serving as a lever for calf muscles.
The talus, often called the ankle bone, is positioned superior to the calcaneus and connects the foot to the lower leg bones, the tibia and fibula. It transmits the weight of the entire body to the foot, playing a role in ankle movement.
The navicular bone is boat-shaped and located on the inner side of the foot. It articulates with the talus posteriorly and the three cuneiform bones anteriorly, acting as a link in force transfer.
The cuboid bone is cube-shaped and situated on the outer side of the foot, anterior to the calcaneus. It provides stability to the lateral column of the foot and helps maintain the lateral longitudinal arch.
There are three wedge-shaped cuneiform bones: the medial, intermediate, and lateral cuneiforms. The medial cuneiform is the largest of the three and is located on the inner side of the foot, articulating with the navicular and the first metatarsal. The intermediate cuneiform is the smallest of the cuneiforms, positioned between the medial and lateral cuneiforms, articulating with the navicular and the second metatarsal. The lateral cuneiform is situated between the intermediate cuneiform and the cuboid, articulating with the navicular and the third metatarsal.
How Tarsal Bones Work Together
The tarsal bones function collectively to provide stability and flexibility to the foot. Their arrangement enables the foot to support body weight efficiently and adapt to various surfaces during activities like walking, running, and jumping. The way these bones articulate creates complex joints that facilitate a wide range of motion.
These bones form the ankle joint and the subtalar joint, allowing for movements such as dorsiflexion (pointing toes up), plantarflexion (pointing toes down), inversion (tilting the sole inward), and eversion (tilting the sole outward). The talus is central to the ankle joint’s smooth movement and weight distribution. The calcaneus provides a stable base and acts as a shock absorber during impact.
The tarsal bones also contribute to forming the foot’s arches: the medial and lateral longitudinal arches, and the transverse arch. These arches distribute body weight evenly across the foot, absorb shock, and store energy for propulsion during movement.