Calcaneus Anatomy and Attachments

Last Updated on June 2, 2025

The calcaneus is the bone of the hindfoot and is the largest of the tarsal bones. It forms the prominence of the heel and plays a crucial role in weight-bearing and gait.

Structure of Calcaneus

The calcaneus is roughly cuboidal in shape and is directed forwards, upwards, and laterally.
It features six distinct surfaces: anterior, posterior, superior (dorsal), inferior (plantar), lateral, and medial.

Anterior Surface

The anterior surface is the smallest of the calcaneus. It is covered by a concavo-convex, sloping articular surface for the calcaneocuboid joint and is roughly triangular. This surface is concave in an oblique inferolateral plane and convex in a plane perpendicular to this.

Posterior Surface

The posterior surface is convex, dome-shaped, and broader at its lower part. It can be divided into three areas:

Lower area: Covered by dense fibrofatty tissue of the plantar heel pad, this area supports body weight during standing.

Upper area: Smooth, slopes anteriorly, and supports a bursa that lies between it and the Achilles tendon.

Middle area: Receives the insertion of the Achilles tendon (tendo calcaneus) and, to a lesser extent, the plantaris tendon.

Superior (Dorsal) Surface

The superior surface of the calcaneus is divided into articular and non-articular parts.

• Nonarticular portion: Forms about one-third of the total superior surface and extends posteriorly to form the heel. It is convex side-to-side, concave anteroposteriorly, and supports a fat pad situated anterior to the Achilles tendon.
• Articular portion: Located anteriorly, it has an oval facet that faces superiorly and is tilted anteriorly. This articular portion is convex anteroposteriorly and articulates with the posterior calcaneal facet on the undersurface of the talus.
• Calcaneal sulcus: A deep groove anterior to the posterior facet, directed posteromedially. Along with a similar groove on the talus, it forms the sinus tarsi—a key anatomical canal in the hindfoot.
• Anterior and middle facets: The middle facet lies on a medially projecting process (sustentaculum tali) and articulates with the middle calcaneal facet on the talus.
  
  The anterior facet lies on the anterior process of the calcaneus and articulates with the anterior calcaneal facet on the talus.
  
  The rough surface, anterior and lateral to these facets, gives attachment to ligaments and origin to the extensor digitorum brevis.

Inferior (Plantar) Surface

The plantar surface is broader posteriorly and convex from side to side.
Its main prominence is the calcaneal tuberosity, which has a central longitudinal depression dividing it into a smaller lateral process and a larger, broader medial process.

• Lateral process: Gives origin to part of the abductor digiti minimi.
• Medial process: Provides attachment for the abductor hallucis, flexor digitorum brevis, and the plantar aponeurosis.

Lateral Surface

The lateral surface is rough, nearly flat, and broadest posteriorly. Anteriorly, a small prominence called the peroneal (fibular) tubercle or trochlea is present. This ridge separates two grooves:

• The superior groove is for the tendon of the peroneus brevis.
• The inferior groove is for the tendon of the peroneus longus.

A small tubercle in the middle of the lateral surface gives attachment to the calcaneofibular ligament.

Medial Surface

The medial surface is concave from above downward, the concavity accentuated by a shelf-like projection called the sustentaculum tali.
This projection extends medially from the anterosuperior border and bears an articular surface for the middle calcaneal facet. Its lower surface is grooved to house the tendon of the flexor hallucis longus. The medial margin forms a rough strip, convex from anterior to posterior.

Attachments and Relations of the Calcaneus

Attachments on Posterior Surface

The middle rough area on the posterior surface receives the insertion of the tendocalcaneus and of the plantaris. The upper region is covered by a bursa. The lower area is covered by dense fibrofatty tissue and supports the body weight while standing.

Attachments on Dorsal or Superior  Surface

The lateral part of the nonarticular area on the anterior part of the dorsal surface provides;

• Origin to the extensor digitorum brevis
• Attachment to the stem of the inferior extensor retinaculum
• Attachment to the stem of the bifurcate ligament

Sulcus calcanei provides attachment to the interosseous talocalcaneal ligament medially and the cervical ligament laterally.

Attachments on Plantar Surface

The attachments on the plantar surface are as follows;

The medial tubercle

• Medially
  • The origin of the abductor hallucis
  • Attachment to the flexor retinaculum
• Anteriorly
  • Flexor digitorum brevis
  • Attachment to the plantar aponeurosis

The lateral tubercle

• Origin to the abductor digiti minimi, the origin extends to the front of the tubercle.
• The anterior tubercle
  • Along with the rough area in front, the short plantar ligament.
  • The rough strip between the three tubercles – Long plantar ligament.

Attachments on Lateral Surface

The peroneal tubercle – Slip from the inferior peroneal retinaculum.

The calcaneofibular ligament is attached about I cm behind the peroneal trochlea.

Attachments on Medial Surface

• The groove on the lower surface of the sustentaculum tali is occupied by the tendon of the flexor hallucis longus.
• The medial margin of the sustentaculum tali
  • Spring ligament
  • Slip from the tibialis posterior in the middle
  • Superficial fibers of the deltoid ligament along the length
  • Medial talocalcaneal ligament posteriorly.
  • Below the groove for the flexor hallucis longus, the medial surface gives origin to the fleshy fibers of the medial head of the accessory flexor digitorum.

Ossification of Calcaneus

• One primary and one secondary center.
• Primary center – During the 3^rd month of intrauterine life.
• Secondary center 6-8 years to form a scale-like epiphysis on the posterior surface
• Fuses with the rest of the bone by 14-16 years.

Side Determination of Calcaneus

• The anterior surface is small and bears a concavoconvex articular facet for the cuboid.
• The posterior surface is large and rough.
• The dorsal or superior has a large, convex articular surface in the middle.
• The plantar surface is large and triangular.
• The lateral surface is flat
• The medial surfaceis concave from above downwards.

Blood Supply of Calcaneus

Blood supply of the calcaneus is by calcaneal branches, which arise from the deep perforator, the peroneal, and the posterior tibial arteries.

Clinical Significance of Calcaneum

• Gastrocnemius, soleus, and plantaris are posterior compartment muscles of the leg and aid in walking, running, and jumping. Their specific functions include plantarflexion of the foot, flexion of the knee, and steadying the leg on the ankle during standing.
• The calcaneus is a frequently injured bone, especially in a fall from height. Most of the calcaneal fractures are treated by nonoperative means, but surgery for displaced fractures is required.
• The calcaneus is surrounded by minimal soft tissue, and surgical incisions need to be carefully planned because of wound healing problems in the area.

References

• Gupton M, Özdemir M, Terreberry RR. Anatomy, Bony Pelvis and Lower Limb: Calcaneus. [Updated 2023 May 23]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK519544/
• Keener BJ, Sizensky JA. The anatomy of the calcaneus and surrounding structures. Foot Ankle Clin. 2005 Sep;10(3):413-24. [PubMed]