Calcaneus

Calcaneus

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In humans, the calcaneus (from the Latin calcaneum, meaning heel) or heel bone is a bone of the tarsus
Tarsus (skeleton)
In tetrapods, the tarsus is a cluster of articulating bones in each foot situated between the lower end of tibia and fibula of the lower leg and the metatarsus. In the foot the tarsus articulates with the bones of the metatarsus, which in turn articulate with the bones of the individual toes...

 of the foot
Foot
The foot is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made up of one or more segments or bones, generally including claws...

 which constitute the heel
Heel
In human anatomy, 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.- Human anatomy :...

. In some other animals, it is the point of the hock
Hock (zoology)
The hock, or gambrel, is the joint between the tarsal bones and tibia of a digitigrade or unguligrade quadrupedal mammal, such as a horse, cat, or dog...

.

Human anatomy


In humans, the calcaneus is the largest of the tarsal bones and the largest bone of the foot. In it, several important structures can be distinguished:

The posterior half of the bone is the tuber calcanei. On its lower edge on either sides are its lateral and medial processes (serving as the origins of the abductor hallucis
Abductor hallucis muscle
The Abductor hallucis lies along the medial border of the foot and covers the origins of the plantar vessels and nerves.It arises from the medial process of the tuberosity of the calcaneus, from the laciniate ligament, from the plantar aponeurosis, and from the intermuscular septum between it and...

 and abductor digit minimi
Abductor digiti minimi muscle (foot)
The Abductor digiti minimi is a muscle which lies along the lateral border of the foot, and is in relation by its medial margin with the lateral plantar vessels and nerves....

). The Achilles tendon
Achilles tendon
The Achilles tendon , also known as the calcaneal tendon or the tendo calcaneus, is a tendon of the posterior leg. It serves to attach the plantaris, gastrocnemius and soleus muscles to the calcaneus bone.- Anatomy :The Achilles is the tendonous extension of 3 muscles in the lower leg:...

 is inserted into a roughened area on its superior side, the cuboid bone articulates with its anterior side, and on its superior side are three articular surfaces for the articulation with the talus bone
Talus bone
-External links:* *...

. Between these superior articulations and the equivalents on the talus is the tarsal sinus (a canal occupied by the interosseous talocalcaneal ligament
Interosseous talocalcaneal ligament
The interosseous talocalcaneal ligament forms the chief bond of union between the bones.It is, in fact, a portion of the united capsules of the talocalcaneonavicular and the talocalcaneal joints, and consists of two partially united layers of fibers, one belonging to the former and the other to the...

). On the medial side of the bone, below the middle talar facet, is the sustentaculum tali
Sustentaculum tali
At the upper and forepart of the medial surface of the calcaneus is a horizontal eminence, the sustentaculum tali , which gives attachment to the plantar calcaneo-navicular ligament, tibiocalcaneal ligament, and medial talocalcaneal ligament.This eminence is concave above, and articulates with the...

(which serves for the attachment of several other ligaments). On the lateral side is commonly a tubercle called the peroneal trochlea
Trochlear process
The two oblique grooves of the lateral surface of the calcaneus are separated by an elevated ridge, or tubercle, the trochlear process , which varies much in size in different bones.Its chief anatomical significance is as a point of divergence of the previously common pathway shared by the...

, under which is a groove for the tendon of the peroneus longus.
In the calcaneus, an ossification center is developed during the 4-7th intrauterine month.
With normal axial alignment in the hindfoot, the axes of the tibia and calcaneus lie on a vertical line (pes rectus). If the calcaneal axis 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).

Horse


The calcaneus has two articulations, being part of the Proximal intertarsal joint and the Talocalcaneal joint. As in humans it is the insertion
Insertion
Insertion may refer to:*Insertion , the point of a tendon or ligament onto the skeleton or other part of the body*Insertion , the addition of DNA into a genetic sequence*Insertion loss, in electronics...

 of the gastrocnemius and superficial digital flexor tendons. The point of the calcaneus is covered by the calcanean bursa
Bursa (anatomy)
A bursa is a small fluid-filled sac lined by synovial membrane with an inner capillary layer of slimy fluid . It provides a cushion between bones and tendons and/or muscles around a joint. This helps to reduce friction between the bones and allows free movement...

.

See also

  • Calcar
    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 , this is to help spread the interfemoral membrane , which is part of the wing membrane between the tail and the hind...

  • Bone terminology
  • Calcaneal fracture
    Calcaneal fracture
    Calcaneal fracture, also known as Lover's fracture and Don Juan fracture, is a fracture of the calcaneus. It is usually caused by a fall from height when one lands on his or her feet. These fractures represent approximately 2% of all fractures but 60% of tarsal bone fractures...

    , also known as Lover's fracture and Don Juan fracture
  • Terms for anatomical location