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. In some other animals, it is the point of the hock.

Structure

In humans, the calcaneus is the largest of the

tarsal bone In the human body, the tarsus is a cluster of seven articulating bones in each foot situated between the lower end of the tibia and the fibula of the lower leg and the metatarsus. It is made up of the midfoot (cuboid, medial, intermediate, and la ...

s and the largest bone of the foot. Its long axis is pointed forwards and laterally. The

talus bone The talus (; Latin for ankle or ankle bone), talus bone, astragalus (), or ankle bone is one of the group of foot bones known as the tarsus. The tarsus forms the lower part of the ankle joint. It transmits the entire weight of the body from the ...

, calcaneus, and

navicular bone The navicular bone is a small bone found in the feet of most mammals. Human anatomy The navicular bone in humans is one of the tarsal bones, found in the foot. Its name derives from the human bone's resemblance to a small boat, caused by th ...

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 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 In the human body, the cuboid bone is one of the seven tarsal bones of the foot. Structure The cuboid bone is the most lateral of the bones in the distal row of the tarsus. It is roughly cubical in shape, and presents a prominence in its inferi ...

articulates with its anterior side. On its superior side there are three articular surfaces for the articulation with the

. Between these superior articulations and the equivalents on the talus is the tarsal sinus (a canal occupied by the

interosseous talocalcaneal ligament The interosseous talocalcaneal ligament forms the chief bond of union between the talus and calcaneus. It is a portion of the united capsules of the talocalcaneonavicular and the talocalcaneal joints, and consists of two partially united layers ...

). 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 t ...

of the ankle-joint. 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 In human anatomy, the fibularis longus (also known as peroneus longus) is a superficial muscle in the lateral compartment of the leg. It acts to tilt the sole of the foot away from the midline of the body ( eversion) and to extend the foot downwar ...

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 In human anatomy, the subtalar joint, also known as the talocalcaneal joint, is a joint of the foot. It occurs at the meeting point of the talus and the calcaneus. The joint is classed structurally as a synovial joint, and functionally as a pla ...

. The point of the calcaneus is covered by the calcanean bursa.

Development

In the calcaneus, an

ossification center An ossification center is a point where ossification of the cartilage begins. The first step in ossification is that the cartilage cells at this point enlarge and arrange themselves in rows.Gray and Spitzka (1910), page 44. The matrix in which t ...

develops during the 4th– 7th week of

fetal development Prenatal development () includes the development of the embryo and of the fetus during a viviparous animal's gestation. Prenatal development starts with fertilization, in the germinal stage of embryonic development, and continues in fetal devel ...

Function

Three muscles insert on the calcaneus: the

gastrocnemius The gastrocnemius muscle (plural ''gastrocnemii'') is a superficial two-headed muscle that is in the back part of the lower leg of humans. It runs from its two heads just above the knee to the heel, a three joint muscle (knee, ankle and subtalar ...

soleus In humans and some other mammals, the soleus is a powerful muscle in the back part of the lower leg (the calf). It runs from just below the knee to the heel, and is involved in standing and walking. It is closely connected to the gastrocnemius mu ...

, and

plantaris The plantaris is one of the superficial muscles of the superficial posterior compartment of the leg, one of the fascial compartments of the leg. It is composed of a thin muscle belly and a long thin tendon. While not as thick as the achilles te ...

. These muscles are part of the

posterior compartment of the leg The posterior compartment of the leg is one of the fascial compartments of the leg and is divided further into deep and superficial compartments. Structure Muscles Superficial posterior compartment Deep posterior compartment Blood ...

and aid in walking, running and jumping. Their specific functions include

plantarflexion Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...

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 connects ...

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 Tarsal coalition is an abnormal connecting bridge of tissue between two normally-separate tarsal bones. The term 'coalition' means a coming together of two or more entities to merge into one mass. The tissue connecting the bones, often referred ...

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