A tarsus is the part of the foot in vertebrates located between the metatarsus (the long bones of the foot) and the lower leg. It also refers to the set of small bones that make up this region, providing support for the foot, including the ankle, heel, and arch.
Tarsus Explained
The tarsus plays a crucial role in weight-bearing, locomotion, and shock absorption. Its complex structure of multiple bones allows for flexibility and stability during movement.
Components of the Tarsus
The tarsus is composed of several bones, which vary slightly across different vertebrate species. In humans, the seven tarsal bones are:
- Talus (Astragalus): This bone articulates with the tibia and fibula of the lower leg, forming the ankle joint. It plays a key role in transmitting weight from the leg to the foot.
- Calcaneus: The largest tarsal bone, forming the heel. It is the point of attachment for the Achilles tendon.
- Navicular: Located on the medial (inner) side of the foot, it articulates with the talus and cuneiform bones.
- Cuboid: Situated on the lateral (outer) side of the foot, it articulates with the calcaneus and metatarsals.
- Cuneiforms (Medial, Intermediate, and Lateral): These three wedge-shaped bones are located between the navicular and metatarsal bones, contributing to the transverse arch of the foot.
Function of the Tarsus
The tarsus performs several vital functions:
- Weight-Bearing: Distributes body weight across the foot.
- Shock Absorption: Helps to absorb impact during activities like walking and running.
- Flexibility and Movement: Allows for a range of motion at the ankle and foot.
- Stability: Provides a stable base of support.
Clinical Significance
Injuries and conditions affecting the tarsus can significantly impact mobility and quality of life. Examples include:
- Ankle sprains: Ligament injuries around the ankle joint.
- Fractures: Breaks in the tarsal bones.
- Tarsal tunnel syndrome: Compression of the tibial nerve in the tarsal tunnel (similar to carpal tunnel syndrome in the wrist).
- Plantar fasciitis: Inflammation of the plantar fascia, a thick band of tissue on the bottom of the foot, often related to the calcaneus.
In summary, the tarsus is a complex and essential part of the foot, crucial for movement, weight-bearing, and stability. Understanding its structure and function is important for diagnosing and treating foot and ankle problems.
