The Skeletal System?
Due the help of the 206 bones in our body, our body will neither be saggy nor shapeless. Bones are the primary organs of the skeletal system, providing a rigid and support framework for the whole body. They are moist living organs that are strong and light, hence permitting easy movement.
Of the Skeletal System
The skeleton gives us support with its bones, forming the body’s support framework. Our delicate organs such as the heart are protected by our bones. For example, the skull protects our brain. Also, with the aid of the muscular system, our bones which have muscles anchored on them provide us with movement. This happens when the muscles contract and shorten, pulling on bones and therefore move them.
Types of Bones
Some bones are solid with an area of spongy bone on the inside, while others are filled with juicy jelly-like red marrow. Though bones come in many shapes and sizes, there are classified under four types-long, short, flat and irregular bones. Here is some brief information about the more important bones in our body:
Skull: Protects the brain.
Shoulder Blade: Also known as scapula.
Ulna: One of two long bones found in the lower arm.
Radius: Shorter than Ulna (The second bone found in the lower arm).
Upper Arm Bone: Also known as humerus (funny bone), linking the shoulder to the lower arm.
Sternum: Known as breastbone, some of the ribs are attached to it by cartilage.
Ribs: Protects the heart and lungs.
Pelvic: Known as hip or gridle, supports organs in the abdomen and anchors the legs.
Thigh Bone: Largest bone in the body.
Shin Bone: A strong bone connecting the knee to foot.
Fibula: A long narrow bone supporting the ankle.
A long bone has 6 main parts, consisting of:
1. Diaphsys (dye-AF-i-sis): A hollow tube made of hard compact bone, hence a rigid and strong structure light enough in weight to permit easy movement.
2. Medullary Cavity: The hollow area inside the diaphysis of a bone, containing soft, yellow bone marrow, an inactive, fatty form of marrow found in the adult skeleton.
3. Epiphyses (eh-PIF-i-sees): Red bone marrow fills in small spaces in the spongy bone composing the epiphyses.
4. Articular cartilage: A thin layer of cartilage covering each epiphysis, acting like a small rubber cushion.
5. Perosteum: A strong fibrous membrane covering a long bone apart from the joint surfaces.
6. Endosteum: A thin membrane that lines the medullary cavity.
A joint is formed when bones of a skeleton are fitted together. Although we have over 200 joints in our bodies, here are the main types of joints:
1. Ball and Socket Joint: These allow movement in all directions.
2. Ellipsoidal Joint: These allow movement from side to side.
3. Hinge Joint: These allow bending and straightening.
4. Pivot Joint: These allow the head to turn.
5. Plane Joint: These allow limited sliding movements.
6. Saddle Joint: These allow rotation in two directions.