The Skeletal SystemEvery movement is possible because
of the muscles working with the bones – skeletal system.
Functions of the Skeletal System:
1. Anchor for body’s movement2. Provides support3. Protects soft organs inside the
body.
Classification of Bones
• Long bones – arms and legs
• Short bones – feet and hands
• Irregular bones – spine
• Flat bones – ribs and skull
What are Bones Made Of???
• Bones are made of soft and hard material
• Are living tissue
• They have spaces inside – allow blood and nutrients to pass through
Two Types of Bone Tissue
Compact Bone – Outside of the boneSupportive tissue of the
bodyIs the part we call the skeleton
Spongy Bone – Tissue inside the boneStrong, but lightweight
Marrow and Blood Cells
• Marrow – inside the spongy bone tissue, produces blood cells
• The blood brings nutrients to the bone cells and carries waste materials away.
Two Main Divisions in the Skeleton
Axial Skeleton – Central part of the Skeleton
Forms the axisProvides support and
protectionIncludes the skull, spinal column, ribs
Appendicular Skeleton – attached to the axis skeleton.
Allows movementShoulder, legs, arms, knees,
etc.
The Skeleton Changes as We Grow
• Infancy – Skull is made up of several bones that have spaces between them – The spaces gradually grow together.
• Childhood – Bone growth occurs at growth plates, a flexible, firm connective tissue. The length and shape of bones is determined by growth plates.
• Adolescence – Bones stop growing at the end of adolescence – the growth plate becomes hard, then arms and legs stop growing and the skull plates fuse together.
• Adulthood – As people age, more bone is broken down than is formed. Bones become less dense and can break more easily.
Joints Connect Parts of the Skeletal System
• Joint – A place at which two parts of the skeletal system meet.
Three Types of Joints:Immoveable – locks bones together like
puzzle pieces. Ex: bones of skullSlightly moveable – enables you to flex
slightly. Ex: ribs connected to sternumFreely Moveable – joints that allow your
body to bend and to move. Ligaments hold the bones together at moveable joints.
Ligaments & Tendons• A ligament is a strong,
flexible band.• A ligament links or
connects bones together.
• A tendon is a cord made of tough, white tissue that attaches muscles to bones.
• A tendon connects muscles to bones.