Tarsal Bones: Names, Functions, and Clinical Relevance of the Seven Ankle Bones

What are the seven ankle bones called?

The seven bones collectively known as the ankle bones, more accurately termed the tarsal bones, are the talus, calcaneus, navicular, medial cuneiform, intermediate cuneiform, lateral cuneiform, and cuboid. These bones form the proximal part of the foot, playing a critical role in weight-bearing, shock absorption, and complex foot movements.

The Tarsal Bones: Architects of the Ankle and Foot

The human ankle and foot comprise a complex network of 26 bones, 33 joints, and over 100 muscles, tendons, and ligaments. Among these, a group of seven bones known as the tarsal bones form the posterior and mid-foot, acting as the foundation for the entire structure. While often colloquially referred to as "ankle bones," it's crucial for fitness professionals and enthusiasts to understand their distinct roles and names, as they are integral to both the ankle joint complex and the broader function of the foot.

Naming the Seven Tarsal Bones

Each of the seven tarsal bones possesses a unique shape and position, contributing to the intricate mechanics of the foot. They are:

• Talus: This is the most superior of the tarsal bones, situated directly beneath the tibia and fibula. It forms the crucial talocrural joint (the true ankle joint) with these lower leg bones, allowing for dorsiflexion and plantarflexion. The talus is unique in that no muscles attach directly to it, relying entirely on ligaments and surrounding muscles for its stability and movement.
• Calcaneus: Commonly known as the heel bone, the calcaneus is the largest of the tarsal bones and forms the posterior-inferior aspect of the foot. It is the primary bone for weight bearing during standing and walking, and it serves as the attachment point for the Achilles tendon, facilitating powerful plantarflexion.
• Navicular: Located on the medial side of the foot, anterior to the talus, the navicular bone is boat-shaped. It plays a significant role in connecting the talus to the cuneiform bones, contributing to the medial longitudinal arch of the foot.
• Medial Cuneiform: This is the largest of the three cuneiform bones, positioned on the medial side of the foot, anterior to the navicular. It articulates with the navicular posteriorly and the first metatarsal anteriorly, forming a critical link in the medial arch.
• Intermediate Cuneiform: The smallest of the cuneiforms, this wedge-shaped bone sits between the medial and lateral cuneiforms, anterior to the navicular. It articulates with the second metatarsal.
• Lateral Cuneiform: Also wedge-shaped, the lateral cuneiform is located on the lateral side of the intermediate cuneiform, anterior to the navicular. It articulates with the third metatarsal.
• Cuboid: Situated on the lateral side of the foot, anterior to the calcaneus, the cuboid bone is somewhat cube-shaped. It articulates with the calcaneus posteriorly and the fourth and fifth metatarsals anteriorly, forming part of the lateral longitudinal arch.

Functional Significance of the Tarsal Bones

Beyond mere identification, understanding the tarsal bones' individual and collective roles is fundamental to appreciating foot and ankle biomechanics:

• Weight Bearing and Distribution: The calcaneus and talus bear the brunt of body weight, distributing forces efficiently through the foot's arches.
• Shock Absorption: The arrangement of the tarsals and their articulations, particularly within the arches, allows for the dissipation of ground reaction forces during impact activities like running and jumping.
• Propulsion: During the push-off phase of gait, the tarsals act as rigid levers, transferring power from the calf muscles to the metatarsals and toes for forward propulsion.
• Adaptability to Uneven Surfaces: The multiple joints between the tarsal bones allow the foot to adapt to varied terrains, maintaining balance and stability.
• Mobility and Stability: The tarsal bones contribute to the complex movements of inversion and eversion (subtalar joint, primarily talus and calcaneus), which are crucial for dynamic balance and navigating uneven ground.

Clinical Relevance and Injury Considerations

A thorough understanding of the tarsal bones is indispensable for preventing and managing injuries. Disruptions to these bones and their surrounding soft tissues can lead to significant pain and functional limitations:

• Fractures: While less common than ankle sprains, fractures of the talus or calcaneus can be severe due to their weight-bearing roles and potential for avascular necrosis (in the talus).
• Sprains: Ligamentous injuries, particularly to the lateral ankle ligaments, often involve the relationship between the talus, calcaneus, tibia, and fibula.
• Arch Problems: Dysfunction or misalignment of the navicular and cuneiforms can contribute to conditions like flat feet (pes planus) or high arches (pes cavus), impacting gait and overall lower limb mechanics.
• Tarsal Tunnel Syndrome: Compression of the tibial nerve as it passes through the tarsal tunnel (a space near the medial malleolus, involving the talus, calcaneus, and navicular) can cause pain, numbness, and tingling.

Conclusion

The seven tarsal bones—talus, calcaneus, navicular, medial cuneiform, intermediate cuneiform, lateral cuneiform, and cuboid—are far more than just "ankle bones." They are the intricate building blocks that underpin the incredible strength, flexibility, and adaptability of the human foot. A comprehensive grasp of their anatomy and biomechanics is essential for anyone serious about optimizing performance, preventing injuries, and maintaining lifelong foot and ankle health.