The skeleton is a mobile framework of bones. It provides a ridged support structure for the body. The bones also serve as levers for the action of muscles.
The human skeleton consists of 206 bones. At birth, bones are made up of cartilage. However, as the baby grows into a child, calcium forms. This hardens the cartilage to become bone. Bones that are developed have a compact outer layer and a honeycomb-like structure. The bones are complex and re-model themselves according to the stress that they are put under. The skeleton renews itself every two years.
About two thirds of bone tissue is made up of mineral components, in other words calcium and salt. These two are responsible for bones’ rigidity. One third of the tissue of bones is organic compounds which give them elasticity. Both minerals and organic compounds are essential to the make-up of bones. If bones aren’t rigid, they would not keep their shape. If bones aren’t elastic, they would break and shatter.
Three forces that bones of the skeleton undergo
- Gravitational strain as bones support the weight of the entire body,
- Muscle contraction as they move against resistance, and
- External pressure from objects, such as lifting boxes or suitcases.
Functions of bones
- To provide attachment points for muscles,
- To protect soft body parts,
- To store calcium and other minerals,
- To synthesise blood cells, and
- To give the body shape and form.
What are the types of bones?
There are five types of bones that make up the human skeleton. These are:
- Flat bones which are compressed and thin. They have two compact bone surfaces. Examples are the scapular, sternum and skull.
- Irregular bones do not have a regular shape. Examples of these types of bones are the vertebrae as well as some hip and skull bones.
- Short bones are cube like and are spongy in nature, for example wrists and ankles.
- Long bones have a shaft and two extremities. Examples of these bones are bones of the limb such as the femur and humerus.
- Sesamoid bones are cartilage-covered bones that develop in a tendon. These occur in areas where the tendon is compressed against a body surface. The sesamoid bone can slide on the surface and prevent occlusion of the blood supply during compression. The patella, or the knee cap, is a good example of this type of bone.
How are bones structured?
Cartilage covers articulating surfaces of bones (where joints are found). It is the non-calcified tissue of the skeleton and protects the underlying bone tissue. Joint cartilage (like all cartilage) does not contain blood vessels. It receives nutrients from the synovial fluids in the bone that surrounds it.
Cartilage can become damages by trauma or excessive wear. Rheumatoid arthritis and osteoarthritis are the two main diseases involving damage to the joint cartilage. It causes pain and stiffness of the joint and surrounding muscles.
The hollow part of the bone contains bone marrow. The marrow is red in children but becomes yellow in adults as much is replace by fatty tissue.
This is the membrane which covers the external bone.
The vertebral bones are some of the most important in the human body as they house your spinal cord which is responsible for conducting nerve impulses to various parts of the body to help you move. Thus, personal trainers need to be very aware of how these function. Trifocus Fitness Academy’s Dissection of the Vertebrae Course will give you an in-depth understand of how these vital parts of the body work.