Bone Types & Composition ANATOMY Unit 4 Notes: Bone Types & Composition

(1) Skeletal Parts Bones Joints Cartilage Marrow

(2) Skeletal Function Support Protection Movement Framework for posture Limbs act as pillars Rib cage supports thoracic wall Protection Ribs protect lungs and heart Skull protects brain Vertebrae protect spinal cord 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: Dislocations: 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: Membranes: 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)