The Skeletal System

The Skeletal System The skeletal system protects and supports the body. Skeleton = Greek word meaning “a dried body” Functions: Provides shape Provides support and protection Allows movement Stores minerals Produces blood

Bones Bones are living tissues that can grow and repair themselves, Connective tissue. Connective tissue provides support for your body and connects all its parts. Types of Connective Tissue: Bone – provides support and shape. Blood – delivers food and oxygen to the cells and carries away wastes. Fat – keeps the body warm, cushions structures and stores energy.

Formation of Bone At birth humans have more than 300 bones. As humans grow and develop, bones grow longer and fuse together. By age 18 bones are completely ossified (hardened) and stop growing longer. An average adult has 206 bones.

Bone Composition Bones are composed of three layer of connective tissue: Periosteum – outermost layer contains blood vessels that bring nutrients and oxygen to the bone. Compact bone – dense layer of bone consists of blood vessels, nerve cells, and living bone cells. Spongy bone – located in the ends and middle of long bones. Porous and lightweight but strong and supportive. Contains bone marrow.

Bone Composition

Other Components of Bone Red Blood Cells White Blood Cells Bone Marrow Located inside the spongy bone. 2 Types: Red Marrow – produces red and white blood cells. Produces 500 billion red blood cells per day! Yellow Marrow – fat cells that store energy. Fat Fat

Cranium Mandible Clavicle Scapula Sternum Humerus Ribs Vertebral Column Pelvic Girdle Radius Ulna Carpals Metacarpals Phalanges Femur Patella Tibia Fibula Tarsals Metatarsals Phalanges

Total Bone Count by Category

Bone Classification Flat Bones Long Bones Irregular Bones Sesamoid Bones Short Bones

Bone Classification Long Bones Examples: longer than they are wide. have a shaft with heads at both ends. Contain mostly compact bone. Examples: Humerus, Radius, Ulna, Femur, Tibia, Fibula, Clavicle, Metacarpals, Metatarsals and Phalanges

Bone Classification 2. Short Bones Examples: Carpals and Tarsals Cube shaped. Generally spongy bone. Examples: Carpals and Tarsals Tarsals

Bones of the Hands & Feet Carpals Tarsals Metacarpals Metatarsals Phalanges Phalanges

Bone Classification 3. Flat Bones Thin and flat. Usually curved.

Male vs. Female Pelvic Girdles

Bone Classification 4. Irregular Bones Examples: Irregularly shaped. Do not fit into any other bone classification. Examples: Vertebrae Sacrum Mandible

Bone Classification 5. Sesamoid Bones Examples: embedded in tendons and usually related to joint surfaces. modify pressure, to diminish friction, and occasionally to alter the direction of a muscle pull. Examples: Patella

Joints A place where two or more bones meet – Joint 2types: A. Immovable Immovable Joints – NO movement Cranium B. Movable Ball-and- Socket = widest range of movement Shoulder and hip Gliding – some movement in all directions Wrist and ankles Hinge – only back and forth Elbow and knee Pivot – one bone rotates around another Forearm, neck

Joint Types Immovable Pivot Ball and Socket Hinge Gliding Knee - Hinge Hip - Ball and Socket

Tendons & Ligaments

Cartilage Located between two adjoining bones. Cushions bones from sudden jolts Provides a slippery surface to reduce friction. Cartilage between Femur and Tibia Cartilage Cartilage