| Calcaneus | |
|---|---|
 The calcaneus forms the bony part of theheel. It forms a joint with thetalus bone, thesubtalar joint. | |
 Bones of thefoot, with the calcaneus shown in red | |
| Details | |
| Identifiers | |
| Latin | calcaneus, calcaneum, os calcis |
| MeSH | D002111 |
| TA98 | A02.5.11.001 |
| TA2 | 1468 |
| FMA | 24496 |
| Anatomical terms of bone | |
In humans and many other primates, thecalcaneus (/kælˈkeɪniəs/; from the Latincalcaneus orcalcaneum, meaning heel;[1]pl.:calcanei orcalcanea) orheel bone is abone of thetarsus of thefoot which constitutes theheel. In some other animals, it is the point of thehock.
In humans, the calcaneus is the largest of thetarsal bones and the largest bone of the foot. Its long axis is pointed forwards and laterally.[2] Thetalus bone, calcaneus, andnavicular bone are considered the proximal row of tarsal bones.[3] In the calcaneus, several important structures can be distinguished:[3]
There is a largecalcaneal tuberosity located posteriorly on plantar surface with medial and lateral tubercles on its surface. Besides, there is another peroneal tubercle on its lateral surface.[2] On its lower edge on either side are its lateral and medial processes (serving as the origins of theabductor hallucis andabductor digiti minimi). TheAchilles tendon is inserted into a roughened area on its superior side and thecuboid bone articulates with its anterior side.[citation needed] On its superior side there are three articular surfaces for the articulation with thetalus bone.[2] Between these superior articulations and the equivalents on the talus is thetarsal sinus (a canal occupied by theinterosseous talocalcaneal ligament).[citation needed] At the upper and forepart of the medial surface of the calcaneus, below the middle talar facet, there is a horizontal eminence, thetalar shelf (alsosustentaculum tali).[2] Sustentaculum tali gives attachment to theplantar calcaneonavicular (spring) ligament, tibiocalcaneal ligament, and medial talocalcaneal ligament. This eminence is concave above, and articulates with the middle calcaneal articular surface of thetalus; below, it is grooved for the tendon of theflexor hallucis longus; its anterior margin gives attachment to the plantar calcaneonavicular ligament, and its medial margin to a part of thedeltoid ligament of theankle-joint.
On the lateral side is commonly a tubercle called thecalcaneal tubercle (or trochlear process). This is a raised projection located between the tendons of theperoneus longus andbrevis. It separates the two oblique grooves of the lateral surface of the calcaneus (for the tendons of the peroneal muscles).
Its chief anatomical significance is as a point of divergence of the previously common pathway shared by the distal tendons of peroneus longus and peroneus brevisen route to their distinct respective attachment sites.[3]
The calcaneus is part of two joints: the proximal intertarsal joint and thetalocalcaneal joint. The point of the calcaneus is covered by the calcaneanbursa.
In the calcaneus, anossification center develops during the4th–7th week offetal development.[3]
Three muscles insert on the calcaneus: thegastrocnemius,soleus, andplantaris. These muscles are part of theposterior compartment of the leg and aid in walking, running and jumping. Their specific functions includeplantarflexion of the foot, flexion of the knee, and steadying the leg on the ankle during standing. The calcaneus also serves as origin for several short muscles that run along the sole of the foot and control the toes.
 |  |
| Muscle | Direction | Attachment[4] |
|---|---|---|
| Gastrocnemius | Insertion | Calcaneal tubercle through the achilles tendon |
| Soleus | Insertion | Calcaneal tubercle through the achilles tendon |
| Plantaris | Insertion | Calcaneal tubercle either directly or through the achilles tendon |
| Extensor digitorum brevis | Origin | Dorsal side of calcaneus |
| Abductor hallucis | Origin | Medial process of calcaneus |
| Extensor hallucis brevis | Origin | Dorsal side of calcaneus |
| Abductor digiti minimi | Origin | Calcaneal tubercle |
| Flexor digitorum brevis | Origin | Calcaneal tubercle |
| Quadratus plantae | Origin | Lateral and medial processes of calcaneus |
Normally thetibia sits vertically above the calcaneus (pes rectus). If the calcaneal axis between these two bones is turned medially the foot is in an everted position (pes valgus), and if it is turned laterally the foot is in an inverted position (pes varus).[5]
The talar shelf is typically involved in subtalar or talocalcanealtarsal coalition.
