The Skeletal System By: Shawna Salazar

What is the Skeletal System? Your Skeletal system is all of the bones in the body and the tissues such as tendons, ligaments and cartilage that connect them. Your teeth are also considered part of your skeletal system but they are not counted as bones. Your teeth are made of enamel and dentin. Enamel is the strongest substance in your body. The average adult human skeleton consists of 206 bones.

How does the skeletal system help us? Support- The main job of the skeleton is to provide support for our body. Without your skeleton your body would collapse into a heap. Your skeleton is strong but light. Protection- Your skeleton also helps protect your internal organs and fragile body tissues. The brain, eyes, heart, lungs and spinal cord are all protected by your skeleton. Your cranium protects your brain and eyes. Movement- Bones provide the structure for muscles to attach so that our bodies are able to move. Tendons are tough inelastic bands that hold attach muscle to bone.

Who has more bones, a baby or an adult? Babies have more than adults! At birth, you have about 300 bones. As you grow older, small bones join together to make big ones. Adults end up with about 206 bones.

What are bones made of? A typical bone has an outer layer of hard or compact bone, which is very strong, dense and tough. Inside this is a layer of spongy bone, which is like honeycomb, lighter and slightly flexible. In the middle of some bones is bone marrow, where new cells are constantly being produced for the blood. Calcium is an important mineral that bone cells need to stay strong. This is why they tell us to drink low-fat milk for strong, healthy bones.

How do bones break and heal? Bones are tough and usually don't break even when we have some pretty bad falls. Bones will bend a little, but if you fall the wrong way from some playground equipment or maybe your bike or skateboard you can break a bone. Doctors call a broken bone a fracture. There are many different types of fractures. Luckily, bones are made of living cells. When a bone is broken your bone will produce lots of new cells to rebuild the bone. These cells cover both ends of the broken part of the bone and close up the break.

The Skull The skull is not one bone, but is made up of several connected bone plates. The bones of the skull protect the brain from trauma and injury. The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium In humans, the skull is made up of 22 bones.

Ribs Twelve pairs of rib bones wrap around the body to protect organs such as the heart and the lungs. The rib cage is also called the thoracic cage. The rib cage is also known for providing the core portion for the skeleton. The rib cage mainly protects the lungs.

Humerus The humerus is the main bone found in the upper arm. This bone allows the body to push and pull objects. Anatomically, it connects the scapula and the lower arm (consisting of the radius and ulna), and consists of three sections. The upper extremity consists of a rounded head, a narrow neck, and two short processes

Radius and Ulna The forearm, or lower arm, contains two major bones, the radius and ulna. These are parallel to each other and aid in mobility and arm movements.

Spine The spine is composed of 26 individual bones, called vertebrae. These bones work together to support the back and protect the spinal cord from injury.

Pelvis and Leg Bones The bones of the pelvis serve as a solid connection point for the joints of the legs. In the leg, the femur--or thigh bone--connects to the lower fibula and tibia bones. These bones are the largest in the body, supporting both weight and movement.