1. ANATOMY
Unit 4 Notes:
Bone Types &
Composition

2. (1) Skeletal Parts
• Bones
• Joints
• Cartilage
• Marrow

3. (2) Skeletal Function
1. Support
– Framework for posture
– Limbs act as pillars
– Rib cage supports thoracic wall
2. Protection
- Ribs protect lungs and heart
- Skull protects brain
- Vertebrae protect spinal cord
3. Movement
- Attachment sites for muscles and tendons
- Muscles use bones as levers
- Joints between allow for range of motion

4. …Function Cont’d…
4. Mineral & Growth Factor Storage
- Reservoir for calcium and phosphate
- Releases minerals into blood
- Growth factors (insulin, transforming factor,
morphogenic proteins) in bone
5. Blood Cell Formation
- Marrow within cavities of bones (primarily long)
- Marrow initiates hematopoeisis (blood cell
formation)

5. (3) How are bones hinged together?
• Joints: Connection between two bones.
– Filled with cartilage (padding)
• Allow for wider range of movement.
– Circular
– Angular
• Reduce rigidity of bone structure.
• *Cartilage within joints (in between bones) provides shock
absorption, and decreases friction.

6. (4) Injuring Joints
• Sprains:
– Ligaments reinforcing a joint are stretched or torn
– If torn badly, can be replaced with muscle
– Usually result from inflexibility or irregular
movement
• Dislocations:
– Bones are forced out of alignment
– Usually result from serious falls and contact sports
– Results in stretching of joint ligaments, leading to
future dislocations

7. (5) What are the Bone Regions?
• Axial
– Down the center of body
– Skull, vertebral column, rib cage, center pelvis
• Appendicular
– Off the sides of body
– Upper and lower limbs, shoulder and hip bones

9. (6) What are the types of bones?
• Long
• Short
• Flat
• Irregular

11. (7) Long Bones
• Longer than they are wide
• Has a shaft and 2 ends
• Weight bearing bones (like steel beams)
• Provide the greatest structure and support
• Examples:
– All limb bones
– Except…. Kneecap, Wrist and Ankle bones

13. (8) Short Bones
• Cube Shaped
• Allow for wider range of movement
• Examples:
– Wrist
– Ankle

15. (9) Flat Bones
• Thin, flat and curved
• Protect soft tissue (like plates of armor)
• Examples:
– Sternum
– Shoulder blades
– Ribs
– Skull bones

17. (10) Irregular Bones
• Complicated, unusual shapes
• Muscles, tendons, ligaments usually
attach to these
• Examples:
– Vertebrae
– Hip bones

19. (11) Bone Structure
• Unique based on location + bone type.
• Compact Bone (Outer Layer):
– Dense
– Smooth and Solid to naked eye
• Spongy Bone (Inner Layer):
– Hole-y (like a honeycomb)
– Made of small needle-like, flat pieces called “trabeculae”
– Open spaces between trabeculae are filled with red or
yellow bone marrow

22. (12) Structure of a Long Bone
• Diaphysis:
– Center, main shaft
– Long part of bone
– Made of very thick compact bone surrounding a central
marrow cavity
• Epiphysis:
– Ends of bone
– Wider than diaphysis
– Made of compact bone which surrounds spongy bone.
– Joint surface of each epiphysis is covered with hyaline
cartilage

23. • Epiphyseal Line:
– Remnant of Epiphyseal Plate
– Found in adult bones
– Shows amount of cartilage growth during
adolescence
• Membranes:
– Periosteum = Around the outside
• Richly supplied with nerve fibers, lymphatic vessels and
blood vessels
• Provides anchoring points for tendons and ligaments
– Endosteum = Around the inside
• Surrounds the spongy bone

25. (13) Chemical Composition of Bone
• Contains organic & inorganic components
• Organic:
– Cells (osteoblasts, osteocytes, osteoclasts)
– Osteoid
• Made of glycoproteins and collagen fibers
• Secreted by osteoblasts
• “filler matrix” around cells
– Contribute to flexibility and tensile strength
• Inorganic:
– Mineral Salts (calcium phosphates)
– Contribute to hardness of bone (allowing for compression
resistance)