Introduction to Bone
The human body is made up of so many things like bone, cartilages, bone marrow, muscles, blood, etc. Among all these things, bone is considered most important for making our body. In a newly born baby, there are approx 300 bones which because of fusion are converted into 206 bones in adult humans. There are so many functions which are performed by bones like they provide shape to the body, they also protect internal organs like brain, heart, lungs, etc. they also store various important minerals like calcium and phosphate as they help in making bone strong from both inside and outside. It is bone only where red blood cell formation takes place. And apart from this one of the most important functions of bone is by providing movement.
Bones of Foot
The bones which are present in foot provide mechanical support for all the soft tissues which are present in foot and also help the foot withstand the weight of the body whilst standing and in motion. There are mainly three types of bones present in the foot, they are:
Tarsals – It is a combination of seven irregularly shaped bones. They are located proximally in the foot in the ankle area of the foot.
Metatarsals – They act as a connection between the phalanges to the tarsals. They are mainly five in number i.e. one for each digit.
Phalanges – The bone is commonly known as bones of the toes. Each toe of a human being has three phalanges – proximal, intermediate, and distal.
Division of Foot
The foot is mainly divided into three regions, they are:
1. Hindfoot: talus and calcaneus
2. Midfoot: navicular, cuboid and cuneiforms
3. Forefoot: metatarsals and phalanges
Anatomy of Foot
A. Tarsals: This bone of foot is organised in three rows, they are proximal, intermediate and distal.
Proximal is commonly known as hindfoot. The proximal tarsal is made up of talus and calcaneus. And they are made up of the hindfoot, forming the bony framework around the proximal ankle and heel.
Talus: Talus is considered as the most superior of the tarsal bones. Its main function is the distribution of whole body weight to the foot. Talus mainly has three articulation they are:
Superiorly – ankle joint i.e. between the talus and the bones of the leg (the tibia and fibula).
Inferiorly – subtalar joint i.e. between the talus and calcaneus.
Anteriorly – talonavicular joint i.e. present between the talus and the navicular.
Main Function of Talus:
1. One of the main functions of the talus is to transmit forces from the tibia to the heel bone (known as the calcaneus).
2. There are various ligaments which are attached to the talus.
Calcaneus: it is considered as the largest tarsal bone and lies just beneath the talus where it makes the heel portion. Calcaneus mainly has two articulations, they are: superiorly (between calcaneus and talus) and anteriorly ( between the calcaneus and the cuboid).
B. Metatarsals
They are located in the forefoot i.e. area between the tarsals and phalanges. They are numbered I-V (medial to lateral). The structures of each metatarsal are similar in nature.
They are of convex shape from the dorsal side and have head, neck, shaft, and base from distal to the proximal end.
Metatarsals mainly have three or four articulations:
Proximally (tarsometatarsal joints) i.e. they are present between the metatarsal bases and the tarsal bones.
Laterally (intermetatarsal joint) i.e. they are present between the metatarsal and the adjacent metatarsals.
Distally (metatarsophalangeal joint) i.e. they are present between the metatarsal head and the proximal phalanx.
C. Phalanges
They are mainly the bones of the toes. They are similar in structure to the metatarsals as each phalanx consists of a base, shaft, and head.
FAQs on Bones of The Foot
1. How many bones are in a single human foot, and what are their main groups?
A single human foot contains 26 bones, which are organised into three main groups to provide structure and support. These groups are:
- Tarsals (7 bones): These form the ankle and upper part of the foot.
- Metatarsals (5 bones): These long bones connect the tarsals to the toes.
- Phalanges (14 bones): These are the bones that make up the toes.
2. What are the seven tarsal bones and what is their function?
The seven tarsal bones form the posterior part of the foot (the ankle and heel). They are irregularly shaped and crucial for bearing weight. The seven bones are the talus, calcaneus (heel bone), navicular, cuboid, and three cuneiforms (medial, intermediate, and lateral). The talus and calcaneus carry the most body weight.
3. What is the role of the five metatarsal bones?
The five metatarsals are long bones located between the tarsals and the phalanges. Their primary role is to form the arches of the foot, which are essential for absorbing shock during activities like walking and running. They also act as a rigid lever to help propel the body forward.
4. How are the 14 phalanges arranged in the toes?
The 14 phalanges are the bones of the toes. The arrangement is specific: the big toe (hallux) has two phalanges (a proximal and a distal phalanx), while the other four toes each have three phalanges (proximal, middle, and distal). This structure allows for flexibility and balance.
5. Why are the arches of the foot structurally important for movement?
The arches, formed by the tarsal and metatarsal bones, are critical for two main reasons. First, they act as natural shock absorbers, distributing body weight and reducing the impact on joints during movement. Second, they provide a spring-like action, or propulsion, which is essential for efficient walking, running, and jumping.
6. What are sesamoid bones and what is their significance in the foot?
Sesamoid bones are small, independent bones that are embedded within a tendon or muscle. In the foot, two prominent sesamoid bones are typically found in the tendon that runs to the big toe, just beneath the first metatarsal head. Their main function is to reduce friction and increase the mechanical advantage of the tendon, improving the toe's leverage and strength.
7. Is there a simple mnemonic to remember the names of the tarsal bones?
Yes, a common mnemonic to remember the seven tarsal bones is: "Tiger Cubs Need MILC". This helps recall the bones in a specific order:
- T - Talus
- C - Calcaneus
- N - Navicular
- M - Medial cuneiform
- I - Intermediate cuneiform
- L - Lateral cuneiform
- C - Cuboid
8. How do the bones of the foot differ from the bones of the hand?
While structurally similar, the bones of the foot and hand are adapted for different primary functions. The tarsals in the foot are larger and stronger than the carpals in the wrist to support body weight. The metatarsals are more rigid and form arches for stability, whereas the metacarpals in the hand are more mobile to allow for grasping. Finally, the phalanges of the hand are longer and more dexterous for fine motor skills, while those in the foot are shorter and primarily provide balance.
