Bones, bones, bones
By Joanna George-Johnson, Contributor

Students preparing for the CSEC examinations taken by thousands of Caribbean students each year. This is one of the significant achievements of CARICOM. - Rudolph Brown/Chief Photographer

• Many activities of the human body depend on its bones.
  
  
• The full complement of bones that make up the human body is called its skeleton.
• The human skeleton is made up of about 206 bones.
  
  
• Unlike some other organisms, such as crabs, insects, etc., we have our skeleton on the inside.
  
  
• Skeletons that are on the inside of the organism are called endoskeletons.

Functions of the skeleton

The skeleton provides four main functions:

• Protection: The heart and lungs are protected by the ribs.
  
  
• Support: It holds us upright and provides a place for tissues and organs.
  
  
• Movement: Working together with our muscles, we are able to move parts of our anatomy where joints are found, e.g. legs for walking.
  
  
• Making red blood cells: Both red and white blood cells are made in the bone marrow. (This can be found in the centre of most long bones. i.e., that 'stuff' that oozes out of chicken bones when you bite into it.)

Our backbone

Our backbone is made up of 33 short bones. All together they are called the vertebrae. The vertebra is a very important set of bones in the human body. They serve many functions:

• Protect the spinal column
• Keep us upright
• Allows for bending and twisting movements of our head and upper body.

The typical vertebral bone

All bones found in the vertebrae share similar features. Depending on the position of the bone, the parts vary in shape and size.

The diagram below shows a typical bone found in the vertebrae: Part 1 is called the neural spine, part 2 is called the transverse process, part 3 is called centrum, and part 4 is called neural canal.

There are three main types of vertebrae bones that you will need to know for your exams. They are: 1) Cervical, 2) Thoracic, and 3) Lumbar.

They each vary in size and shape depending on their position in the vertebral column. The diagram below shows the three types of vertebrae.

The job of moving by the vertebrae cannot be attributed to the bones alone. There are extremely strong muscles that are associated with each of these bones that assist with both movement and the job of support.

The Long bones

A next set of bones that are needed for your exams are the bones of the limbs. They are sometimes called long bones because of their structure. They tend to be the largest bones found in an organism. They function mainly for movement or locomotion.

• Those of the lower limbs are: femur - thigh bone; tibia and fibula - leg bones.
  
  
• Those of the upper limbs are: humerus - upper arm bone; ulna and radius - lower arm bones.
  
  

Questions to try:

1. What part of the skeleton protects the a) brain b) spinal cord?

2. What part of the skeleton provides support for our upper body?

3. What is the function of the following: neural canal and transverse process?

4. The centrum is made of solid bone; it functions mainly for support and to withstand the pressure from standing. The lower vertebral bones tend to have very large centrum, explain why this is so.

5. From the diagrams of the vertebrae bones above, identify features that distinguish one from the other.

6. Label the bones of the forelimb.

Joanna George-Johnson teaches at Ardenne High School masterbio@gmail.com.