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In humans and many other primates, the calcaneus (; from the Latin ''calcaneus'' or ''calcaneum'', meaning heel) or heel bone is a
bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...
of the tarsus of the foot which constitutes the
heel The heel is the prominence at the posterior end of the foot. It is based on the projection of one bone, the calcaneus or heel bone, behind the articulation of the bones of the lower leg. Structure To distribute the compressive forces exer ...
. In some other animals, it is the point of the hock.


Structure

In humans, the calcaneus is the largest of the tarsal bones and the largest bone of the foot. Its long axis is pointed forwards and laterally. The talus bone, calcaneus, and navicular bone are considered the proximal row of tarsal bones. In the calcaneus, several important structures can be distinguished:Platzer (2004), p 216 There is a large calcaneal tuberosity located posteriorly on plantar surface with medial and lateral tubercles on its surface. Besides, there is another peroneal tubecle on its lateral surface. On its lower edge on either side are its lateral and medial processes (serving as the origins of the
abductor hallucis The abductor hallucis muscle is an intrinsic muscle of the foot. It participates in the abduction and flexion of the great toe. Structure The abductor hallucis muscle is located in the medial border of the foot and contributes to form the promi ...
and abductor digiti minimi). The
Achilles tendon The Achilles tendon or heel cord, also known as the calcaneal tendon, is a tendon at the back of the lower leg, and is the thickest in the human body. It serves to attach the plantaris, gastrocnemius (calf) and soleus muscles to the calcaneus ...
is inserted into a roughened area on its superior side and the cuboid bone articulates with its anterior side. On its superior side there are three articular surfaces for the articulation with the talus bone. Between these superior articulations and the equivalents on the talus is the tarsal sinus (a canal occupied by the interosseous talocalcaneal ligament). At the upper and forepart of the medial surface of the calcaneus, below the middle talar facet, there is a horizontal eminence, the talar shelf (also sustentaculum tali). Sustentaculum tali gives attachment to the plantar calcaneonavicular (spring) ligament, tibiocalcaneal ligament, and medial talocalcaneal ligament. This eminence is concave above, and articulates with the middle calcaneal articular surface of the talus; below, it is grooved for the tendon of the
flexor hallucis longus The flexor hallucis longus muscle (FHL) is one of the three deep muscles of the posterior compartment of the leg that attaches to the plantar surface of the distal phalanx of the great toe. The other deep muscles are the flexor digitorum longus an ...
; its anterior margin gives attachment to the plantar calcaneonavicular ligament, and its medial margin to a part of the
deltoid ligament The deltoid ligament (or medial ligament of talocrural joint) is a strong, flat, triangular band, attached, above, to the apex and anterior and posterior borders of the medial malleolus. The deltoid ligament is composed of 4 fibers: 1. Anterior ti ...
of the
ankle-joint The ankle, or the talocrural region, or the jumping bone (informal) is the area where the foot and the leg meet. The ankle includes three joints: the ankle joint proper or talocrural joint, the subtalar joint, and the inferior tibiofibular ...
. On the lateral side is commonly a tubercle called the calcaneal tubercle (or trochlear process). This is a raised projection located between the tendons of the peroneus longus and brevis. 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 brevis ''en route'' to their distinct respective attachment sites. The calcaneus is part of two joints: the proximal intertarsal joint and the talocalcaneal joint. The point of the calcaneus is covered by the calcanean
bursa ( grc-gre, Προῦσα, Proûsa, Latin: Prusa, ota, بورسه, Arabic:بورصة) is a city in northwestern Turkey and the administrative center of Bursa Province. The fourth-most populous city in Turkey and second-most populous in the ...
.


Development

In the calcaneus, an ossification center develops during the 4th7th week of fetal development.


Function

Three muscles insert on the calcaneus: the gastrocnemius, soleus, and plantaris. These muscles are part of the posterior compartment 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 also serves as origin for several short muscles that run along the sole of the foot and control the toes.


Clinical significance

Normally the
tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it conn ...
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'').''Thieme Atlas of Anatomy'' (2006), p 410 *
Calcaneal fracture A calcaneal fracture is a break of the calcaneus (heel bone). Symptoms may include pain, bruising, trouble walking, and deformity of the heel. It may be associated with breaks of the hip or back. It usually occurs when a person lands on their f ...
, also known as ''Lover's fracture'' and ''Don Juan fracture''


Disease

The talar shelf is typically involved in subtalar or talocalcaneal tarsal coalition.


See also

*
Calcar The calcar, also known as the calcaneum, is the name given to a spur of cartilage arising from inner side of ankle and running along part of outer interfemoral membrane in bats, as well as to a similar spur on the legs of some arthropods. The c ...
* Bohler's angle *
Sanders classification The Sanders classification is a system of categorizing intra-articular calcaneal fractures based on the number of articular fragments seen on the coronal CT image at the widest point of the posterior facet. Classification See also *Foot f ...


Additional images

File:Left Calcaneus animation03.gif, Left calcaneus. Animation. File:Ospied-en.svg, Bones of foot File:Calcaneus.jpg, 3D rendering of a left calcaneus derived from CT scan data. The calcaneus is white, and the other bones of the foot and ankle are clear to illustrate the position and relationship of the calcaneus to the other tarsal bones.


Notes


References

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External links

* ()
3D printable calcaneus model
free download in STL format (Embodi3D.com) {{Authority control Bones of the lower limb Vertebrate anatomy Bones of the foot Tarsal bones