Types of Bones in Body

Bones can be classified by many methods. Here we discuss different types of bones one by one

Types of Bones According to Shape

Long bones

Each long bone has an elongated shaft or diaphysis and two expanded ends (epiphyses) which are smooth and articular. The shaft typically has 3 surfaces separated by 3 borders, a central medullary cavity, and a nutrient foramen directed away from the growing end. Examples of typical long bones are humerus, radius, ulna, femur, tibia and fibula, metacarpals, metatarsals and phalanges

Short bones

Their shape is usually cuboid, cuneiform, trapezoid, or scaphoid. Examples: carpal and tarsal bones.

Flat Bones

Flat bones resembles shallow plates and form boundaries of certain body cavities. Examples: bone in the vault of the skull, ribs, sternum and scapula.

Irregular Bones

Vertebra, hip bone, and bones in the base of the skull.

Pneumatic Bones

Certain irregular bones contain large air spaces lined by epithelium. Examples: maxilla, sphenoid, ethmoid, etc. they make the skull light in weight, help in resonance of voice, and act as air conditioning chambers for the inspired air.

classification of Bones Of Body

Human Skeleton

Sesamoid Bones.

These are bony nodules found embedded in the tendons or joint capsules. They have no periosteum and ossify after birth. They are related to an articular or nonarticular bony surface, and the surfaces of contact are covered with hyaline cartilage and lubricated by a bursa or synovial membrane.

Examples: patella, pisiform, fabella, etc.

Function of the sesamoid bones are not definitely known. Their possible function are:
* To resist pressure;
* To minimize friction;
* To alter the direction of pull of the muscle; and
* To maintain the local circulation.

Accessory (Supernumerary) Bones

These are not always present. They may occur as ununited epiphyses developed from extra centres of ossification. Examples: sutural bones, os trigonum, os vesalianum, etc. In medicolegal practice, accessory bones may be mistaken for fractures. However, these are often bilateral, and have smooth surfaces without any callus.

Developmental Classification

Membrane (Dermal) Bones

THhese types of bones ossify in membrane (intramembranous or mesenchymal ossification), and are thus derived from mesenchymal condensations. Examples: bones of the vault of skull and facial bones.

A defect in membranous ossification causes a rare syndrome called cleidocranial dysostosis. It is characterized by three cardinal features:

* Varying degrees of aplasia of the clavicles;
* Increase in the transverse diameter of cranium, and
* Retardation in fontanelle ossification. It may be hereditary or environmental in origin.

Cartilaginous Bones

These types of bones ossify in cartilage (intracartilaginous or endochondral ossification), and are thus derived from performed cartilaginous models. Examples: bone of limbs, vertebral column and thoracic cage.

A defect in endochondral ossification causes a common type of dwarfism called achondroplasia, in which the limbs are short, but the trunk is normal. It is transmitted as a Mendelian dominant character.

Membrano-Cartilaginous Bones

These ossify partly in membrane and partly in cartilage. Examples: clavicle, mandible, occipital, temporal, sphenoid.

Types of Bones Based on Bone structure

Cortical and Cancellous Bone

Text adapted from BD Chaurasia

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Comments

  1. Akene amos says

    Please,I'd like to know if there are any more classifications of the human bones other than shape and development?

  2. Dr Arun Pal Singh says

    @musa kabiru sulaiman,

    I think you would be better served by consulting books on anatomy.

  3. Dr Arun Pal Singh says

    @Hauwa mohammed,

    I would love to help you but the thing you have asked falls into domain of pure anatomists.

    If you could provide details of the requirement, may be I would be able to guide you.

  4. Jodian Thompson says

    Your information was well read, accurate, it has provide the necessary research that i was seeking. Thank you

  5. A. Mohammed says

    There is a further type of classification which is Internal Organisation I.e. dense (compact/cortical) and spongy (cancellous/trabecular). I think you have failed to include this?