Classification of bones in the human body

By shape, bones are classified into five main types: long , short , flat , irregular and sesamoid .

In relation to location, the bones of the human body are classified as axial , making up the vertical axis of the body (head, trunk and neck). The other bones are appendicular , which form the upper and lower limbs.

Long bones

These are bones whose length, although variable, is greater than their width and thickness. In addition, they are resistant due to their slightly curved structure to absorb the stress generated by body weight.

These bones are made up of a diaphysis, a body formed by compact bone tissue, and epiphysis, which are the ends in spongy bone tissue.

Examples : femur, humerus, radius, ulna, fibula and phalanges.

Short bones

These are bones formed by spongy tissue, whose surface has a thin covering of compact tissue. The shape of these bones is similar to a cube, since the length, height and width are practically the same.

Examples : Wrist bones (carpus) and ankle bones (tarsus).

Pneumatic bones

Pneumatic bones have characteristics that are distinct from other groups and are therefore classified in a specific way. They have cavities, called sinuses, and are lined with air-filled mucous membranes.

Examples : Bones that are part of the skull, such as the jaw and temporal bones.

Laminar bones

They are also called flat or flat bones and provide protection. They are generally formed by two sheets of compact tissue that are almost parallel and separated by a layer of spongy tissue, characterizing them as thin and compact bones in the body.

Examples : Bones of the skull, such as the frontal and parietal bones, ribs and scapula.

Irregular bones

They are bones with a complex structure and a variable composition of spongy bone tissue and compact bone tissue.

Examples : Vertebrae and calcaneus.

Sesamoid bones

These are bones whose diameter can vary from millimeters to centimeters when they develop in certain tendons of the body, providing protection to regions that withstand friction, tension and physical stress.

A person may have a different number of sesamoid bones, however, normally everyone has patellas, the largest sesamoid bones.

Examples : Patellas located in the tendon of the quadriceps femoris muscle.

Sutural bones

Also called Wormian bones , they are classified as such because they are located between the joints, also called sutures, of the cranial bones. These are supernumerary or accessory bones , which can grow in some people and not in others.

Read about the Bones of the Human Body

Skeletal System Summary

The skeletal system, in addition to bones, is composed of other structures, such as cartilage, ligaments and tendons.

Its main functions are:

• Support : provides support for soft tissues, as well as structuring the human body;
• Protection : prevents internal organs from being injured;
• Movements : bones and skeletal muscles act together, allowing movement;
• Mineral storage : Calcium and phosphorus are stored to give strength to bones.

Learn more about the Skeletal System

Bone structure

Bones are living structures that make up the skeletal system of the human body, being formed mainly by bone connective tissue.

There are two types of bone: compact , the rigid part, and spongy , which is a less dense layer.

The anatomy of long bones, for example, is made up of:

• Diaphysis : body of the bone;
• Epiphases : ends of the bone;
• Metaphyses : intermediate region located between diaphysis and epiphysis;
• Cartilage : located above the epiphase and is responsible for reducing friction;
• Periosteum : thin membrane that covers the bone;
• Medullary cavity : space inside the bone;
• Endosteum : thin lining that surrounds the medullary cavity.

Learn more about Bone Tissue

Division of the human skeleton

In total, the 206 bones that make up the bone structure of the human body are divided into two parts: axial skeleton and appendicular skeleton.

The axial skeleton is made up of 80 bones located along the central axis of the body and divided between the head, rib cage and spine. Its main function is to protect the central nervous system and organs in the rib cage region.

The appendicular skeleton is made up of 126 bones divided between the upper and lower limbs, and is responsible for carrying out movements and supporting the body.