Body SystemsBody SystemsBones and MusclesBones and Muscles

Skeletal Systems

4 functions

Key role in movement

Provides a strong, stable, and mobile framework on which muscles can act

Supports and protects internal organs

Storage center for essential body materials (ex: calcium and phosphorous)

Manufactures blood cells

Structure of Skeletal System

206 bones

Axial skeleton

80 bones around the core of the body:

examples: skull, spine, ribs, and sternum

Appendicular skeleton

126 bones outside the core frame (appendicular - appendices)

examples: shoulders, arms, hands, hips, legs, and feet

Types of Bones

Four types of bones:

Long - femur

Short - wrist

Flat - rib

Irregular - vertebrae

Cartilage and Joints

Cartilage: strong, flexible connective tissue (tip of your nose)

Joints: the point at which two bones meet

Ball and socket joint: shoulder

Pivot joint: head and shoulders

Ellipsoidal joint: wrist

Hinge joint: elbow

Ligaments and tendons

Ligaments

Tough bands of fibrous, slightly elastic tissue that bind the bone ends at the joint

Tendons

Fibrous cord that join muscle to bone or to other muscles

Types of Muscles

Cardiac Muscles:

Special type of striated tissue that forms the walls of the heart

Smooth Muscles:

Concerned with internal movements of internal organs (involuntary, like intestines)

Skeletal Muscles:

Striped muscles (striated) that are attached to bones that cause body movements (voluntary)

Flexors: muscles that close a joint

Extendors: muscles that open out a joint

Muscles: Use it or lose it

Atrophy: unused muscles waste away

Muscle tone: the natural tension in the fibers of a muscle