Hey everyone! This is Nicole from Kenhub, and in this tutorial, we will be looking at one of the tarsal bones of the foot – the talus. So as we can see as we return to our lateral view of the foot, we have the talus here highlighted in green. And the talus is one in a group of seven bones of the foot which are collectively referred to as the tarsus. And these seven bones that make up the tarsus are the calcaneus, the cuboid, the lateral cuneiform, the intermediate cuneiform, the medial cuneiform which isn't visible here but lies medial to the intermediate cuneiform, the navicular, and, of course, the talus.
The talus is also known as the ankle bone and, as we can see, it's a saddle-shaped bone located between the tibia and the fibula bones of the lower leg and the calcaneus and the navicular bones of the tarsus which I'll just point out with my mouse here. And so here's the calcaneus – this big bone here – and this is our navicular. And that talus is an important bone for the stability of the ankle due to its central location between the ankle joint which we can't see here, the subtalar joint which is between the talus and the calcaneus here, the talocalcaneonavicular joint which joins the head of the talus with the calcaneus, the plantar calcaneonavicular ligament, and the navicular bones. And the talus bone is described as having three main components – a head, a neck and a body.
So the head of the talus which we can see highlighted in green here is convexly oval in shape and it articulates distally with the proximal end of the navicular bone which is just here. And the image of the talus at the top shows a right talus from a plantar view so if we're looking up at it then this is our medial side over here and our lateral side over here with the body which connects to the calcaneus. And there are two articular surfaces on the plantar surface of the head of the talus and they are separated by smooth ridges – the medial calcaneal facet which is convex and semi-oval in shape is just here resting on the plantar calcaneonavicular ligament which we talked about before and is otherwise known as the spring ligament and the anterior calcaneal facet which is somewhat flattened and articulates with the anterior aspect of the calcaneus over here – and up top here is the surface that articulates with the navicular bone.
The neck of the talus connects the head and the body of the talus and as we can see, it is somewhat narrow and presents a rough surface for the attachments of the ligaments, and probably the neck is a little bit narrower than what is presented on this image but, nevertheless, this is its general area. The deep sulcus tali is found at the neck of the talus and this groove forms the roof of the sinus tali when the talus and calcaneus articulate.
And the body of the talus shown from its plantar surface on the left and dorsal surface on the right has a smooth curved trochlea on its dorsal surface which articulates with the distal end of the tibia. And the talus also forms articulations with the medial malleolus of the tibia on the medial surface of the talar body and with the lateral malleolus of the fibula on the lateral surface of the talar body.
And though there are no muscle attachments, there are several ligaments attached to the body of the talus including the posterior, lateral and medial talocalcaneal ligaments which all contribute to the formation of the subtalar joint also known as the talocalcaneal joint which connects the talus and the calcaneus. Additionally, attachments are found for the deltoid and posterior talofibular ligaments which contributes to the formation of the ankle joints also known as the talocrural joint.
And the talus receives arterial blood from three sources – the posterior tibial artery, the peroneal or fibular artery, and the dorsalis pedis artery. And note that because of the lack of muscular attachment to the talus, its blood supply is considered tenuous and this is important to know clinically as because the talus, which is mostly cartilage, can be difficult to heal in the case of an injury because of its aforementioned lack of blood supply.
Innervation of the talus is provided by the deep fibular nerve, the distal branches of the saphenous nerve, the sural nerve and the posterior tibial nerve which is derived from the tibial nerve shown here.
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