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ANATOMY
Unit 5 Notes:Bone Types & Composition
(1) Skeletal Parts
• Bones
• Joints
• Cartilage
• Marrow
(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
…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)
(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.
(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
(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
(6) What are the types of bones?
• Long
• Short
• Flat
• Irregular
(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
(8) Short Bones
• Cube Shaped
• Allow for wider range of movement
• Examples:– Wrist – Ankle
(9) Flat Bones
• Thin, flat and curved
• Protect soft tissue (like plates of armor)
• Examples:– Sternum– Shoulder blades– Ribs– Skull bones
(10) Irregular Bones
• Complicated, unusual shapes
• Muscles, tendons, ligaments usually attach to these
• Examples:– Vertebrae– Hip bones
(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
(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
• 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
(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)