CALCANEUS ANATOMY
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GENERAL STRUCTURE
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The calcaneus is the largest tarsal bone, located at the lower and posterior part of your foot. It plays a crucial role in transmitting your body's weight to the ground and serves as a lever for the muscles of your calf, contributing to movement and stability.
What is the calcaneus and what does it do?
- Forms the heel of your foot
- Supports the talus above
- Articulates anteriorly with the cuboid bone
- Essential for weight-bearing and locomotion
POSTERIOR EXTREMITY (CALCANEAL TUBEROSITY)
The posterior extremity of the calcaneus, also known as the calcaneal tuberosity, is the prominent projection that forms your heel. It is convex and wider below than above, divided into two processes.
Medial Process
What is the medial process of the calcaneal tuberosity?
- Broader of the two processes
- Attachment site for:
- Abductor hallucis (prominent medial margin)
- Plantar aponeurosis (anteriorly)
- Important for arch support in your foot
Lateral Process
What is the lateral process of the calcaneal tuberosity?
- Smaller, prominent, and rounded
- Origin site for part of the Abductor digiti quinti
- Contributes to your heel stability
SUSTENTACULUM TALI
The sustentaculum tali is a shelf-like projection located above the concavity on the medial surface of the calcaneus. It is a critical structure for supporting the talus.
What is the sustentaculum tali?
- Shelf-like projection on the medial surface
- Supports the talus
- Groove on its plantar surface accommodates the tendon of Flexor hallucis longus
- Important for subtalar joint stability
TARSAL SINUS & CALCANEAL SULCUS
Calcaneal Sulcus
What is the calcaneal sulcus?
- Groove on the calcaneus
- Forms the tarsal sinus (together with the sulcus tali of the talus)
- Located between articular surfaces
Tarsal Sinus
What is the tarsal sinus?
- Formed by the sulcus calcanei of the calcaneus and the sulcus tali of the talus
- Creates a tunnel filled with ligaments
- Contains the interosseous talocalcaneal ligament
- Important for subtalar joint stability
TALAR ARTICULAR SURFACES
The calcaneus has three articular surfaces for articulation with the talus, forming the subtalar joint complex.
Anterior Talar Articular Surface
What is the anterior talar articular surface?
- Located on the calcaneus
- For articulation with the head of talus
- Smallest of the three surfaces
Middle Talar Articular Surface
What is the middle talar articular surface?
- Located on the sustentaculum tali
- Supports the talus
- Often continuous with the anterior surface
Posterior Talar Articular Surface
What is the posterior talar articular surface?
- Large, oval-shaped facet
- Located on the dorsal surface of the calcaneus
- Articulates with the talus
- Largest of the three surfaces
ANTERIOR FEATURES
Fibular Trochlea
What is the fibular trochlea?
- Often indistinctly marked
- Attachment site for the inferior peroneal retinaculum
- Separates two grooves for the tendons of the peronei muscles
Groove for the Tendon of Fibularis Longus
What is the groove for the tendon of fibularis longus?
- Runs obliquely forwards and medialwards on the plantar surface of the cuboid
- Lodges the tendon of Fibularis longus
Articular Surface for the Cuboid
What is the articular surface for the cuboid?
- Triangular shape
- Concave from above downwards and lateralwards
- Convex in the perpendicular direction
- Forms the calcaneocuboid joint
Anterior Process of the Calcaneus
What is the anterior process of the calcaneus?
- Supports the articular surface for the cuboid
- Projects forwards
- Forms part of the calcaneocuboid joint
- Common site for avulsion fractures
BIBLIOGRAPHY
1. Henry G, Warren HL. Osteology. In: Anatomy of the Human Body. 20th ed. Philadelphia: Lea & Febiger; 1918. p. 129–97.