Tarsus (skeleton)

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The tarsus is a group of seven articulate bones in each foot located between the lower end of the tibia and lower leg fibula and metatarsus. It consists of midfoot (cubic, medial, intermediate, and lateral cuneiform, and navicular) and hindfoot (talus and calcaneus).

The tarsus articulates with the metatarsus bone, which in turn articulates with the proximal phalanx of the toes. The joint between the tibia and the fibula above and the tarsus below is referred to as the ankle joint.

In the largest human bone in tarsus is calcaneus, which is the bone that holds the load in the heel.

Video Tarsus (skeleton)

Human anatomy

Bone

The talus or bone of the ankle is securely connected to the two bones of the lower limbs, the tibia and fibula, to form an ankle joint or talocrural joint; inferior, to the subtalar joint, to the calcaneus or heel bone. Together, the talus and calcaneus form hindfoot.

The five irregular bones of the midfoot - cuboid, navicular, and three cuneiform bones - form a foot arch that serves as a shock absorber. The middle leg is connected back and front by the muscles and plantar fascia.

Movement

The complex movement of the subtalar joints occurs in three planes and produces inversion and subtalar eversion. Together with the transverse tarsal joint (ie, the talonavicular and calcaneocuboid joints), the subtalar joint changes the tibial rotation to the fore-leg supine and pronation. The rotational axis in the joint is directed upwards of 42 degrees from the horizontal plane and 16 degrees medial from the midline of the foot. However, together, the subtalar aspect forms the Archimedean screw or spiral, the right hand on the right foot, about the subtalar movement taking place. Thus, during subtalar inversion, the calcaneus also rotates clockwise and is translated forward along the axis of the screw. The average subtalar movement is an inversion of 20-30 degrees and eversion of 5-10 degrees. The functional movement during the gait cycle is 10-15 degrees (the heel strikes the ground with little inversion followed by rapid eversion).

The talonavicular and calcaneocuboid joints (ie between the talus and the navicular bone, and the calcaneus and cuboid bone) form what is called transversal tarsal joints or Chopart joints. It has two axes of motion. Inversion and eversion occur around the longitudinal axis oriented 15 degrees upward from the horizontal plane and 9 degrees medally from the longitudinal axis of the foot. Flexes and extensions occur primarily about a tilted axis oriented 52 degrees upward from the horizontal plane and 57 degrees anteromedially (forward-into). In vitro talonavicular motion is 7 degrees of extension-flexion and 17 degrees of pronation-supination; while the calcaneocuboid movement is 2 degrees of extension-flexion and 7 degrees of pronation-supination.

Movements of the subtalar and transversal joint talar interact to make the legs either flexible or rigid. With the subtalar joints in eversion, the two joints are parallel across the joint, which makes movement in these joints possible. With subtalar junctions in the inversion, the axes of the cross-connections are convergent, the movements within the joint are locked and the center of the rigid.

Maps Tarsus (skeleton)

Other animals

In primitive tetrapods, such as Trematops , tarsus consists of three rows of bones. There are three proximal tarsals, tibiale , intermedium , and fibulare , named after the articulation point with the lower extremity bone. This is followed by a second row of four bones, referred to as centralia (singular: centrale ), and then a distant five tarsal sequence, each articulating with a single metatarsal. In most tetrapods, including all that live today, this simple pattern is modified by the loss and fusion of some bones.

In reptiles and mammals, there are usually only two proximal tars, calcaneus (equivalent to amphibian fibulare) and talus (probably derived from a combination of bones). In mammals, including humans, the talus forms a hinge joint with the tibia, a feature that is highly evolved in artiodactyl. Calcaneus is also modified, forming the heel for the installation of the Achilles tendon. None of these adaptations are found in reptiles, which have relatively simple structures for both bones.

The fifth distal tarsal disappears relatively early in evolution, with the rest being sharp and cuboid-shaped. Reptiles usually maintain two centralities, whereas mammals usually have only one (navicular).

In birds, the tarsus has disappeared, with the proximal tarsal that has fused with the tibia, centrality has disappeared, and the distal bone has fused with the metatarsal to form a single tarsometatarsus bone, effectively providing the third segment leg.

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Additional images

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See also

• Arch of the foot
• Carpus
• Cube-shaped syndrome
• Tarsal tunnel
• Tarsal tunnel syndrome

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Note

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References

• Nordin, Margareta; Frankel, Victor Hirsch (2001). Basic biomechanics of the musculoskeletal system . Lippincott Williams & amp; Wilkins. ISBN 0-683-30247-7.
• "Anatomy of feet and ankles". Podiatry Channel . Retrieved August 30 2009 .
• Romer, Alfred Sherwood; Parsons, Thomas S. (1977). Vertebrate Body Ã,

src: dev.biologists.org

External links

• Diagram, identify bone
• xrayslowerlimb at The Anatomy Lesson by Wesley Norman (Georgetown University) ( xrayfootdorsal )

Source of the article : Wikipedia