The framework of our body Skeletal System The framework of our body

Purpose: 4 Main Functions Supports the structure of the body Gives the body shape Protects vital organs Serves as attachment for muscles

Composition of Skeletal System Contains 206 bones Divided into two parts: Axial Skeleton Appendicular Skeleton

Axial Skeleton Bones that protect vital organs Skull – protects brain Ribs – protects lungs and heart Spinal column – houses and protects spinal cord

Axial Skeleton

Appendicular Skeleton Appendages – Bones that hang from, or are indirectly attached to axial skeleton Legs Pelvis Arms Shoulders

Appendicular Skeleton

Four Main Shapes of Bones Flat – ribs, shoulder blades Irregular – vertebrae, tiny ear bones Short – wrist and ankle Long – arms, legs, fingers

Flat – Ribs

Flat – Shoulder Blade (Scapula)

Irregular - Vertebrae

Short – Wrist and Ankle

Long – Arms, Legs, & Fingers

Lesson 2: Kinds of Joints Are meeting points between bones Control the amount of movement Are sometimes compared to machines and mechanical gadgets

Number and Types of Joints There are 8 types of joints in the human skeletal system

1. Ball and Socket Allows free movement in all directions Examples: hips, shoulders, largest knuckles

2. Gliding A.K.A. “Plane Joint” and “Washer Joint” Limited tilting with pad of cartilage between bone ends Examples: joints between vertebrae in backbone, wrist, and ankle

3. Hinge Allows the bones to only move back and forth (no side to side) Examples: Elbow, knee, smaller knuckles of fingers, toes

4. Pivot Allows rotation, but no other movement Examples: neck, forearm (ulna/radius)

5. Saddle Allows movement in two directions, but no rotation Shaped like a saddle for tilting and sliding Example: Thumb

6. Ellipsoid Allows circular and bending movement but no rotation Examples: between finger bones

7. Condylar Similar to hinge but with slight rotation to allow the joint to “lock” into an extended position Examples: knee

8. Fixed or Suture Joint Allows no movement at all because the bones are firmly joined together Examples: Between bones of cranium around brain