The Structure and Functions of Bones

1.

Support

The skeleton is the framework of the body, it supports the softer tissues and provides points of attachment for most skeletal muscles.

2.

Protection

The skeleton provides mechanical protection for many of the body's internal organs, reducing risk of injury to them.

For example, cranial bones protect the brain, vertebrae protect the spinal cord, and the ribcage protects the heart and lungs.

3.

Assisting in Movement

Skeletal muscles are attached to bones, therefore when the associated muscles contract they cause bones to move.

4.

Storage of Minerals

Bone tissues store several minerals, including calcium (Ca) and phosphorus (P). When required, bone releases minerals into the blood - facilitating the balance of minerals in the body.

5.

Production of Blood Cells

The red bone marrow inside larger bones, such as the scapulae, is the site of production of red blood cells.

(Red blood cells, white blood cells and blood platelets are described on structure and functions of blood.)

6.

Storage of Chemical Energy

With increasing age some bone marrow changes from 'red bone marrow' to 'yellow bone marrow'.

Yellow bone marrow consists mainly of adipose cells, and a few blood cells. It is an important chemical energy reserve.

1.

Long bones:

Long bones have greater length than width and consist of a shaft and a variable number of endings (extremities). They are usually somewhat curved for strength.

Examples include femur, tibia, fibula, humerus, ulna and radius.

2.

Short bones:

Short bones are roughly cube-shaped and have approximately equal length and width.

Examples include ankle and wrist bones.

3.

Flat bones:

Flat bones have a thin shape / structure and provide considerable mechanical protection and extensive surfaces for muscle attachments.

Examples include cranial bones (protecting the brain), the sternum and ribs (protecting the organs in the thorax), and the scapulae (shoulder blades).

4.

Irregular bones:

Irregular bones have complicated shapes and so cannot be classified into any of the above (shape-based) categories. Their shapes are due to the functions they fulfill within the body e.g. providing major mechanical support for the body yet also protecting the spinal cord (in the case of the vertebrae).

Examples include the vertebrae and some facial bones.

5.

Sesamoid bones:

Sesamoid bones develop in some tendons in locations where there is considerable friction, tension, and physical stress. They may therefore form in the palms of the hands and the soles of the feet, however their presence and quantity varies considerably from person to person.

Examples common to everyone include the patellae (kneecaps).

6.

Sutural bones:

Sutural bones are classified by their location rather than by their shape. They are very small bones located within the sutural joints between the cranial bones. The number of sutural bones varies considerably from person to person, therefore these are un-named bones.