Tarsus – Anatomy, Function and Conditions
The tarsus is the group of seven bones forming the rear and middle part of the foot, connecting the lower leg to the metatarsus and playing a key role in walking and standing.
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The tarsus is the group of seven bones forming the rear and middle part of the foot, connecting the lower leg to the metatarsus and playing a key role in walking and standing.
What is the Tarsus?
The tarsus refers to the collection of seven bones that make up the rear and middle portion of the foot. It forms the anatomical bridge between the lower leg (tibia and fibula) and the metatarsus (the long bones of the foot). The tarsus bears the full weight of the body during standing, walking, and running, making it a structure of critical biomechanical importance.
Anatomy – The Seven Tarsal Bones
The seven tarsal bones are commonly divided into two functional groups:
Posterior Tarsus (Proximal Group)
- Calcaneus (heel bone): The largest tarsal bone, forming the heel and serving as the attachment point for the Achilles tendon.
- Talus (ankle bone): Connects the foot to the lower leg via the upper ankle joint (talocrural joint).
Middle and Anterior Tarsus (Distal Group)
- Navicular bone: Located on the medial side, between the talus and the cuneiform bones.
- Cuboid bone: Located on the lateral side, linking the heel to the metatarsus.
- Medial, intermediate, and lateral cuneiform bones: Together with the navicular, they form the foundation of the longitudinal arch of the foot.
Function of the Tarsus
The tarsus serves several key biomechanical functions:
- Load transfer: It transmits body weight from the lower leg to the entire foot.
- Shock absorption: Together with the arches of the foot, the tarsus cushions impact forces during walking and running.
- Mobility: Through the upper and lower ankle joints and the Chopart joint line, the tarsus enables plantarflexion, dorsiflexion, inversion, and eversion of the foot.
Key Joints of the Tarsus
- Upper ankle joint (talocrural joint): The articulation between the talus and the bones of the lower leg (tibia and fibula).
- Lower ankle joint (subtalar joint complex): Includes the subtalar joint (between talus and calcaneus) and the talocalcaneonavicular joint.
- Chopart joint (transverse tarsal joint): A transverse joint line between the posterior and anterior tarsus.
- Lisfranc joint (tarsometatarsal joint): The articulation between the tarsus and the metatarsals.
Common Conditions and Injuries of the Tarsus
Fractures
Fractures of the tarsal bones commonly result from falls from height, sports injuries, or direct trauma. The most frequent include:
- Calcaneal fracture: Often caused by landing on the heel; may involve the subtalar joint.
- Talar fracture: Less common but serious due to the risk of avascular necrosis.
- Lisfranc injury: Traumatic dislocation or fracture at the tarsometatarsal joint complex.
Osteoarthritis (Tarsal Arthritis)
Degenerative changes in the tarsal joints cause pain, stiffness, and reduced mobility of the foot. Risk factors include obesity, previous injuries, and genetic predisposition.
Tarsal Coalition
A tarsal coalition is a congenital abnormal union between two or more tarsal bones, which may be bony, cartilaginous, or fibrous. It often results in a rigid, painful foot and reduced subtalar motion.
Flat Foot (Pes Planus)
A collapse of the longitudinal arch of the foot directly affects the alignment of the tarsal bones – especially the talus and calcaneus – and can lead to long-term complaints affecting the entire musculoskeletal system.
Diagnosis
Several imaging techniques are used to evaluate the tarsus:
- X-ray: First-line imaging for suspected fractures or arthritis; performed in multiple planes.
- Computed Tomography (CT): Provides detailed imaging of fractures and tarsal coalitions.
- Magnetic Resonance Imaging (MRI): Best for assessing soft tissues, ligaments, tendons, and early bone changes such as stress reactions.
- Ultrasound: Useful as a supplementary tool for evaluating tendons and bursae.
Treatment
Treatment depends on the specific condition or injury:
- Conservative treatment: Rest, offloading, orthotic insoles, physiotherapy, and anti-inflammatory medications for arthritis or minor injuries.
- Surgical treatment: Open reduction and internal fixation for fractures; arthrodesis (joint fusion) for advanced arthritis or instability; resection for symptomatic tarsal coalition.
References
- Moore, K.L., Dalley, A.F., Agur, A.M.R. – Clinically Oriented Anatomy, 8th edition. Wolters Kluwer, Philadelphia, 2018.
- Rammelt, S., Zwipp, H. – Tarsal Injuries and Fractures. Der Unfallchirurg, 2013; 116(12): 1055–1072. DOI: 10.1007/s00113-013-2449-5.
- Standring, S. (ed.) – Gray's Anatomy: The Anatomical Basis of Clinical Practice, 42nd edition. Elsevier, Edinburgh, 2021.
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Related search terms: Tarsus + Tarsal bones + Ankle bones