Introduction to the skeletal system

What comes to your mind when you hear the word “skeleton”? Maybe last halloween? While you may associate the skeletal system with the dead, it’s actually an integral part of our living bodies.

It is made up of 206 bones that provide form and support, protect the inner organs, and together with muscles, bones also help in performing different types of movements.

Now, our skeleton can be divided into an axial and an appendicular skeleton. Let’s start with the bones of the axial skeleton, which consists of the bones of the head, neck and trunk.

These bones include the skull or the cranium, a small bone in the neck called the hyoid bone, the vertebral column, and the ribs and sternum.

The appendicular skeleton, on the other hand, consists of the bones of the upper and lower limbs.

Now, bones of the axial and appendicular skeletons are further classified based on their shape as long, short, flat, sesamoid, and irregular bones.

Let’s start with long bones, which are tubular in shape, have a long axis and usually two ends that articulate with other bones. An example is the humerus of the upper arm.

Short bones, on the other hand, are cuboidal in shape, and examples include the carpal bones of the wrist.

Next are flat bones, which are flat, thin, and possibly curved bones that usually protect internal organs. An example of flat bones are the cranial bones that protect the brain.

Next are sesamoid bones, which are particularly unique because they lie within tendons.

The largest sesamoid bone is the patella, or the kneecap, which is a triangular bone that covers the anterior side of the knee joint.

Lastly are irregular bones, which are bones that don’t fall into any of these categories, mainly because they have more complex shapes. Examples of irregular bones are the vertebrae which form the spine.