ANATOMY

Unit 4 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)