The Skeletal System
Start with the complete skeleton and learn the basic functions that bones, joints, and connective tissue perform together.
What is the skeletal system?
The skeletal system is made up of bones, cartilage, ligaments, and the joints that connect them. It gives the body its shape, protects internal organs, and works with the muscular system to make movement possible.
206 bones, one connected frame
The adult skeleton contains 206 bones of many shapes and sizes, from the tiny bones of the ear to the long bones of the legs.
Framework
Bones form the rigid framework that holds the body upright and gives it shape.
Shielding organs
Bones like the skull and ribcage protect vital organs such as the brain, heart, and lungs.
Attachment points
Muscles attach to bones through tendons, and joints allow bones to move against each other.
Minerals and marrow
Bones store calcium and phosphate and house bone marrow, where blood cells are produced.
Two major divisions
Anatomists divide the skeleton into two main parts based on location and function: the axial skeleton, which forms the body's central axis, and the appendicular skeleton, which forms the limbs and their supporting girdles.
Bone is living tissue
Although bones feel solid and unchanging, they are living tissue, supplied with blood vessels and nerves, and constantly being broken down and rebuilt throughout life.
The skeleton is a dynamic organ system.
Bone tissue is continuously remodeled, allowing the skeleton to repair injuries, adapt to physical stress, and regulate mineral levels in the blood.