BONES OF FOOT

BONES OF FOOT

• Tibia, Fibula

• Tarsus (7): talus, calcaneus, cuneiformes (3), cuboid, and navicular

• Metatarsus (5): first, second, third, fourth, and fifth metatarsal bone

• Phalanges (14)

• There can be many sesamoid bones near the metatarsophalangeal joints, although they are only regularly present in the distal portion of the first metatarsal bone.

TIBIA:

• Larger (20% of height) and stronger of the two bones in the leg below the knee in vertebrates (the other being the fibula), and it connects the knee with the ankle bones.

• The tibia is found on the medial side of the leg next to the fibula, and closer to the median plane or centre-line.

• The tibia is connected to the fibula by the interosseous membrane of the leg, forming a type of fibrous joint called a syndesmosis with very little movement.

• The tibia is named for the flute tibia.

• It is the second largest bone in the human body next to the femur.

• The leg bones are the strongest long bones as they support the rest of the body.

FIBULA:

• Fibula or calf bone is a leg bone located on the lateral side of the tibia, with which it is connected above and below. 

• It is the smaller of the two bones, and, in proportion to its length, the slenderest of all the long bones. 

• Its upper extremity is small, placed toward the back of the head of the tibia, below the level of the knee joint, and excluded from the formation of this joint. 

• Its lower extremity inclines a little forward, so as to be on a plane anterior to that of the upper end; it projects below the tibia, and forms the lateral part of the ankle-joint.

TARSUS:

• Tarsus is a cluster of seven articulating bones in each foot situated between the lower end of tibia and fibula of the lower leg and the metatarsus. 

• The tarsus articulates with the bones of the metatarsus, which in turn articulate with the proximal phalanges of the toes. 

• The joint between the tibia and fibula above and the tarsus below is referred to as the ankle joint.

• Largest bone in the tarsus is the calcaneus, which is the weight-bearing bone within the heel of the foot.

• Following are the tarsus bones:

1. Talus or ankle bone :

• Forms the lower part of the ankle joint through its articulations with the lateral and medial malleoli of the two bones of the lower leg, the tibia and fibula.

• Within the tarsus, it articulates with the calcaneus below and navicular in front within the talocalcaneonavicular joint (Ball and socket joint)

• The second largest of the tarsal bones, it is also one of the bones in the human body with the highest percentage of its surface area covered by articular cartilage.

• It have no muscles attachments.

• Through these articulations, it transmits the entire weight of the body to the foot. 

2. Calcaneus or hell bone: 

• Largest of the tarsal bones and the largest bone of the foot.

• The talus bone, calcaneus, and navicular bone are considered the proximal row of tarsal bones.

• Articulates with cuboid bone.

3. Cuneiformes:

• There are three cuneiform bones in the human foot.

– First or medial cuneiform

– Second or intermediate cuneiform also known as the middle cuneiform

– Third or lateral cuneiform

• They are located between the navicular bone and the first, second and third metatarsal bones and are medial to the cuboid bone.

4. Cuboid:

• It 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 inferior (or plantar) surface, the tuberosity of the cuboid.

• The bone provides a groove where the tendon of the peroneus longus muscle passes to reach its insertion in the first metatarsal and medial cuneiform bones.

• First or medial cuneiform

• Second or intermediate cuneiform also known as the middle cuneiform

• Third or lateral cuneiform

5. Navicular:

• It is located on the medial side of the foot, and articulates proximally with the talus, distally with the three cuneiform bones, and laterally with the cuboid.

METATARSALS:

• The metatarsal bones, or metatarsus are a group of five long bones in the foot, located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes.

• They are numbered from the medial side (the side of the great toe): the first, second, third, fourth, and fifth metatarsal.

• The lengths of the metatarsal bones in humans are, in descending order: second, third, fourth, fifth and first.

• The base of each metatarsal bone articulates with one or more of the tarsal bones at the tarsometatarsal joints, and the head with one of the first row of phalanges at the metatarsophalangeal joints. 

• Their bases also articulate with each other at the intermetatarsal joints.

 PHALANGES:

• There are 14 phalanges on each foot

• Three phalanges are present on each toe, with the exception of the large toe, which possess only two.

• The middle and far phalanges of the fourth and fifth toes are often fused together (symphalangism).

• The proximal phalanges are those that are closest to foot join with metatarsals of the foot at metatarsophalangeal joint.

• The intermediate phalanx is not only intermediate in location, but usually also in size.Large toe do not possess a middle phalanx.

• The distal phalanges are the bones at the tips of toes.

• The proximal, intermediate, and distal phalanges articulate with one another through interphalangeal articulations.

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