Joints of the bones of the foot

The bones of the foot are connected to the bones of the leg (ankle joint) and to each other. The bones of the foot form the joints of the tarsal bones, metatarsal bones, and the joints of the toes.

The articulations of the tarsal bones are represented by the subtalar, talocalcaneonavicular, transverse tarsal joint, calcaneocuboid, cuneonavicular and tarsometatarsal joints, strengthened by tightly stretched dorsal and plantar ligaments.

The subtalar joint (art. subtalaris) is formed by the connection of the posterior talar articular surface (calcaneus) and the posterior calcaneal articular surface (talus). The articular surfaces correspond to each other in shape. Movements relative to the sagittal axis are possible.

The talocalcaneonavicular joint (art. talocalcaneo-navicularis) is formed by the articular surface of the head of the talus, articulating with the navicular bone in front and the calcaneus below. The joint capsule is reinforced along the edges of the articular surfaces. The joint is reinforced by several ligaments. The interosseous talocalcaneal ligament (lig. talocalcaneum interosseum) is very strong, located in the sinus of the tarsus, connecting the surfaces of the grooves of the talus and calcaneus. The plantar calcaneonavicular ligament (lig. calcaneonavicular plantare) connects the inferomedial side of the support of the talus and the lower surface of the navicular bone. The talonavicular ligament (lig. talonavicular) connects the dorsal surface of the neck of the talus and the navicular bone.

Movements in this joint occur together with the subtalar joint around the sagittal axis. The talus remains motionless during adduction and abduction. The entire foot moves together with the rotating navicular and calcaneal bones. During adduction of the foot, its medial edge is raised, and the dorsum of the foot rotates laterally. During abduction of the foot, its lateral edge is raised, and its dorsum rotates medially. The total range of motion in this joint relative to the sagittal axis does not exceed 55°.

The calcaneocuboid joint (art. calcaneocuboideum) is formed by the articular surfaces of the calcaneus and cuboid bones facing each other. The joint is saddle-shaped. Its articular surfaces are congruent, and movements are limited. The joint capsule is strengthened mainly by the long plantar ligament (lig. plantare longum). This ligament begins on the lower surface of the calcaneus, fan-shapedly diverges forward and attaches to the bases of the II-V metatarsal bones. Nearby is the strong and short plantar calcaneocuboid ligament (lig. calcaneo-cuboideum plantare).

The calcaneocuboid and talonavicular (part of the talocalcaneonavicular joint) joints are considered the transverse tarsal joint (art. tarsi transversa), or Chopart's joint. In addition to the ligaments that strengthen each of these two joints, the Chopart joint has a common bifurcated ligament (lig. bifurcatum), consisting of two parts. The bifurcated ligament begins on the superolateral edge of the calcaneus. The first part of this ligament - the calcaneonavicular ligament (lig. calcaneo-naviculare) is attached to the posterolateral edge of the navicular bone, the second part - the calcaneocuboid ligament (lig. calcaneocuboideum) - to the back of the cuboid bone. When the bifurcated ligament is cut, the integrity of the foot is disrupted. Therefore, this ligament is called the "key" of the Chopart joint.

The cuneonavicular joint (art. cuneonaviculare) is formed by the flat articular surfaces of the navicular bone and three cuneiform bones. The joint capsule is attached along the edges of the articular surfaces. The joint is strengthened by numerous ligaments: dorsal and plantar cuneiform, interosseous intercuneiform, dorsal and plantar intercuneiform. Movements in the joint are limited.

The tarsometatarsal joints (artt. tarsometatarseae, Lisfranc joint) are formed by flat articular surfaces of the cuboid and cuneiform bones, articulating with the metatarsal bones. There are three independent joints, isolated from each other: the junction of the medial cuneiform and 1 metatarsal bones, the articulation of the 2nd and 3rd metatarsal bones with the intermediate and lateral cuneiform bones, and the cuboid bone with the 4th and 5th metatarsal bones. The joint capsules are stretched and attached along the edges of the articulating surfaces. The joint cavities do not communicate with each other. The capsules are reinforced by the dorsal and plantar tarsometatarsal ligaments (ligg. tarsometatarsalia dorsalia et plantaria). Of great importance are the intra-articular interosseous cuneometatarsal ligaments (ligg. cuneometatarsea interossea). The medial interosseous cuneometatarsal ligament, which connects the medial cuneiform bone and the base of the second metatarsal bone, is called the "key of the Lisfranc joint". Movements in the tarsometatarsal joints are limited.

The intermetatarsal joints (artt. intermetatarseae) are formed by the bases of the metatarsal bones facing each other. The joint capsules are reinforced by transversely located dorsal and plantar metatarsal ligaments (ligg. metatarsdlia dorsalia et plantaria). Between the articular surfaces facing each other, in the articular cavities, there are interosseous metatarsal ligaments (ligg. metatarsalia interossea). Movements in the intermetatarsal joints are limited.

The metatarsophalangeal joints (artt. metatarsophalangeae) are formed by the heads of the metatarsal bones and the bases of the proximal phalanges. The articular surfaces of the phalanges are almost spherical in shape, the articular fossa of the tarsal bones is oval in shape. The capsule of each such joint is thin, reinforced on the sides by collateral ligaments (ligg. collateralia), and below by plantar ligaments (ligg. plantaria). The heads of the metatarsal bones are connected by a deep transverse metatarsal ligament (lig. metatarsale profundum transversum), which fuses with the capsules of all the metatarsophalangeal joints. In the metatarsophalangeal joints, flexion and extension relative to the frontal axis are possible (up to 90° in total). Abduction and adduction around the sagittal axis are possible within small limits.

The interphalangeal joints (artt. interphalangeae), block-shaped, are formed by the base and head of the adjacent phalanges of the toes. The joint capsules are free, attached along the edges of the articular cartilages. Each capsule is reinforced by the plantar and collateral ligaments (ligg. collateralia et ligg. plantaria). The interphalangeal joints perform flexion and extension around the frontal axis. The total range of these movements is no more than 90°.

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