Foot

The foot (pes) is divided into 3 departments: tarsus, metatarsus and fingers. The skeleton of these departments is the tarsi bones (ossa tarsi), the bones of the metatarsalia (ossa metasarsalia) and the bones of the toes (ossa digitorum pedis).

The bones of the tarsus. The tarsus consists of seven spongy bones arranged in two rows. The proximal (posterior) row consists of two large bones: the ram and the heel. The remaining five tarsal bones form a distal (anterior) row.

Talus has a body (corpus tali), a head (caput tali) and a narrow connecting part - a neck (collum tali). On the upper surface is a block of the talus bone (trochlea tali), consisting of three articular surfaces. The upper surface (facies superior) is intended for articulation with the lower articular surface of the tibia. The articular surfaces lying on the sides of the block: the medial ankle surface (facies malleolaris medialis) and the lateral ankle surface (facies malleolaris lateralis) - are articulated with the corresponding articular surfaces of the ankles of the tibial and fibular bones. On the lateral surface of the body is the lateral process of the talus bone (processus lateralis tali).

Behind the block, from the body of the talus, is the posterior process of the talus bone (processus posterior tali). On the process, a furrow is visible for the tendon of the long flexor of the big toe. On the lower side of the talus are three articular surfaces for articulation with the heel bone: anterior, middle and posterior calcaneal articular surfaces (faciei articulares calcanei anterior, media et posterior). Between the middle and posterior articular surfaces is a groove of the talus bone (sulcus tali). The head of the talus is directed forward and medially. To articulate it with the scaphoid bone serves as a rounded navicular articular surface (facies articularis navicularis).

Calcaneus calcaneus is the largest bone of the foot. It is located under the talus bone and extends from under it. Behind the body of the calcaneus is a downward inclined tuber calcanei. On the upper side of the calcaneus, three articular surfaces are distinguished: the anterior, middle and posterior ram joint surfaces (faciei articulares talaris anterior, media et posterior). These surfaces correspond to the heel joints of the talus. Between the middle and posterior articular surfaces, the calcaneus groove (sulcus calcanei) is visible, which together with the same groove on the talus bone forms the sinus tarsi (sinus tarsi). The entrance to this bosom is located on the rear of the foot from its lateral side. From the anterior margin of the calcaneus, from the medial side, a short and thick process departs - the support of the talent bone (sustentdculum tali). On the lateral surface of the calcaneus there is a furrow of the tendon of the long fibular muscle (sulcus tendinis m.peronei longi). On the distal (anterior) end of the calcaneus, for articulation with the cuboid bone, there is a cuboid articular surface (facies articularis cuboidea).

The navicular bone (os naviculare) is located medially, between the talus bone behind and three wedge-shaped bones in front. The proximal concave surface is articulated with the head of the talus. On the distal surface of the scaphoid bone there are three articular sites for connecting with the wedge-shaped bones. At the medial edge is the tuberosity of the scaphoid bone (tuberositas ossis navicularis) - the place of attachment of the posterior tibial muscle.

The sphenoid bones (ossa cuneiformia) - medial, intermediate and lateral - are anterior to the scaphoid bone. The medial wedge bone (os cuneiforme mediale), the largest, joins the base of the metatarsal I bone. The intermediate sphenoid bone (os cuneiforme intermedium) is articulated with the II metatarsal bone, the lateral sphenoid bone (os cuneiforme laterale) - with the III metatarsal bone.

The cuboid bone (os cuboideum) lies in the lateral part of the foot, between the calcaneus and the last two metatarsal bones with which it forms joints. On the medial side of the cuboid bone is an articulation site for the lateral sphenoid bone, and somewhat posteriorly for articulation with the scaphoid bone. On the lower (plantar) side of the cuboid bone is the groove of the tendon of the long fibular muscle (sulcus tendinis m. Peronei longi).

Plusset bones (ossa metatarsi). They include five tubular short bones. The shortest and thickest I metatarsal bone, the longest - II. Each bone has a body (corpus), a caput and a base. The bodies of the metatarsal bones have a convexity, turned in the back side. The bases are provided with articular surfaces for articulation with tarsal bones. The head I of metatarsal bone from the plantar side is divided into two sites, to which contiguous sesamoid bones. The base of I metatarsal bone forms a joint with a medial wedge bone. The bases of the II and III bones are articulated with the intermediate and lateral wedge-shaped bones, and the bases of the IV and V metatarsal bones are with the cuboid bone. On the lateral side of the V metatarsal bone is the tuberosity V of the metatarsals (tuberositas ossis metatarsals) for attachment of the short fibular muscle.

The toes of the foot, like the fingers of the hand, have a proximal phalanx (phalanx proximalis), an average phalanx (phalanx media) and a distal phalanx (phalanx distalis). The skeleton of the 1st toe (hallux) consists of only two phalanges: proximal and distal. Phalanges distinguish between body, head and base. The base of each proximal phalanx has a flattened fossa that serves to articulate with the head of the corresponding metatarsal bone. On the basis of middle and distal phalanges there are pits for articulation with a phalanx head located more proximally. Each distal (nail) phalanx ends with a tubercle (tuberositas phalangis distalis).

The bones of the tarsus and metatarsus do not lie in the same plane. The talus bone is located on the heel, and the scaphoid bone is above the heel and cuboid bones. The bones of the medial edge of the tarsus are elevated in comparison with its lateral margin. With this arrangement of bones, the arches of the foot are formed, which provide a spring support for the lower limb. The arch of the foot has a convex, turned upward. The lateral margin of the foot is lower than the medial edge, which is slightly elevated and open to the medial side. In fact, only a few points serve in the foot for the support: the heel of the calcaneus - at the back, the metatarsal heads, mostly I and V, - in the front. Phalanges of fingers only touch the ground lightly.

Stop as a whole. The foot is adapted to perform a supporting function, which is facilitated by the presence of "tight" joints and powerful ligaments. The bones of the foot are connected, forming arched upward arcs oriented in the longitudinal and transverse directions. All five longitudinal arches start on the calcaneus, fanwise go forward, along the bones of the tarsus to the heads of metatarsal bones. In the transverse direction, all the arches have different heights. At the level of the highest points of the longitudinal arches, an arcuate transverse arch forms. Due to the vigilance of the foot, the foot does not rest on the whole surface of the sole, but has three points of support: the calcaneal tubercle, the head I and V of the metatarsal bones in the front.

The arches of the foot are held by the shape of adjacent bones, ligaments (the so-called passive "puffs" of arches) and muscle tendons (active "puffs"). The most powerful passive puffs of the longitudinal arches of the foot are a long plantar ligament, a plantar calcaneus-navicular and other ligaments. The transverse arch of the foot is strengthened by a deep and transverse metatarsal and other ligaments located in the transverse direction.