The Skeletal System

Definition: –all the bones in the body

The Skeletal System Function –forms an internal, living framework that provides shape and support protects internal organs moves bones forms blood cells stores calcium and phosphorous compounds for later use

Bones Made of layers of living tissue Covered with a tough, tight-fitting membrane called the periosteum

Compact Bone Directly under the periosteum Hard, strong layer Gives bones strength Contains deposits of calcium phosphate Contains bone cells and blood vessels

Spongy Bone Located at the ends of long bones Has many small, open spaces that make bones lightweight Filled with a substance called marrow –yellow composed of fat cells –red produces red blood cells

Cartilage Smooth, slippery, thick layer of tissue Covers the ends of bones Does not contain blood vessels or minerals Flexible and acts as a shock absorber Makes movement easier by reducing friction

Joints Definition: –Any place where two or more bones come together

Joints Kept far enough apart by a thin layer of cartilage so that they do not rub against each other as they move Bones are held in place at joints by a tough band of tissue called ligament

Types of Joints Immovable –Skull –Pelvis Moveable –Pivot –Ball & socket –Hinge –Gliding

Types of Joints Ball and Socket Joint Bone with a rounded end that fits into a cuplike cavity on another bone

Types of Joints Pivot Joint One bone rotates in a ring of another bone that does not move

Types of Joints Hinge Joint Back-and- forth movement like hinges on a door

Type of Joints Gliding Joint One part of a bone slides over another bone