Talus

Key Features & Anatomical Relations

The talus (talar bone, astragalus or ankle bone) is one of the seven tarsal bones of the foot. It has an irregular shape and is found in the proximal row of tarsal bones. The talus is classified as a short bone and includes the following bony features:

- parts: head, neck, and body;

- surfaces: navicular surface, trochlea, and posterior and lateral processes;

- landmarks: medial and lateral malleolar facets, medial and lateral tubercles, and anterior, middle and posterior calcaneal articular facets.

More information regarding these bony features can be found in the Parts, Surfaces and Landmarks tabs for this bone.

The talus is located:

- proximal to the navicular bone;

- distal to the tibia and fibula;

- superior to the calcaneus.

It articulates with the:

- talus and fibula at the ankle joint;

- calcaneus at the subtalar and talocalcaneonavicular joints;

- navicular bone at the talocalcaneonavicular joint.

The talus contributes to the formation of the medial longitudinal arch of the foot.

Ossification

Ossification of the talus occurs at one ossification center, which appears in utero at the sixth month (Standring, 2016).

Variations

In some individuals:

- the neck may present a prominence known as a talar beak;

- the body of talus may present an accessory ossicle, known as the os trigonum, and if this ossicle fuses with the talus it becomes the trigonal process (Tubbs, Shoja and Loukas, 2016).

Surface Anatomy

The following bony features of the talus are relevant to surface anatomy:

- during foot inversion, the border between the superior articular facet and lateral malleolar facet of talus can be palpated anterior to the lateral malleolus;

- anterior to this border is a hollow area, the neck of the talus, which lies posterior to the head of the talus;

- during foot eversion, the neck of the talus can be palpated anterior to the medial malleolus, followed by the head of the talus.

List of Clinical Correlates

- Fracture of talus

- Talocalcaneal coalition

- Talonavicular coalition

- Posterior ankle impingement syndrome

- Subtalar coalition

- Congenital vertical talus

References

Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.

Tubbs, R. S., Shoja, M. M. and Loukas, M. (2016) Bergman's Comprehensive Encyclopedia of Human Anatomic Variation. Wiley.