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Skeletal System. Components. - Cartilage - Bone - Joints - Ligaments (bone to bone) - Tendons (muscle to bone). Functions. - Support - Movement - Protection - Mineral storage - Blood cell synthesis - hematopoiesis. Cartilage. Hyaline
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Components - Cartilage - Bone - Joints - Ligaments (bone to bone) - Tendons (muscle to bone)
Functions - Support - Movement - Protection - Mineral storage - Blood cell synthesis - hematopoiesis
Cartilage • Hyaline • Elastic • Fibrocartilage
Hyaline cartilage - Articular cartilage – covers ends of bones and moveable joints - Costal cartilage – attach ribs to the sternum - Respiratory cartilage – forms respiratory passages and larynx - Nasal cartilage – forms external nose
Elastic cartilage - Forms external ear - Forms epiglottis
Fibrocartilage Withstands heavy pressure & tensile forces - Intervertebral disks - Knees and elbows
Bone • Cell, tissue, organ • Skeleton – Greek for dried up body • Composed of 206 bones 1.Axial skeleton – 80 bones 2.Appendicular skeleton – 126 bones
Classification of bone • Long bones • Short bones • Sesamoid bones • Flat bones • Irregular bones
Long bones - Diaphysis – shaft - Epiphysis – ends of bone; contain red marrow - Medullary cavity – contains yellow marrow - Epiphyseal plate – found between diaphysis and epiphysis; long bone growth
Short bones • Roughly cuboidal in shape
Sesamoid bones form within a tendon e.g. patella
Flat bones Thin, flattened, and slightly curved Diploe – spongy bone found between compact bone layers
Irregular bones • complicated shapes e.g. vertebrae, pelvis
Bone cells • Osteoclast – cells which dissolve bone (puts calcium into the blood for muscular contraction, nerve transmission, blood clotting, etc…) • Osteoblast – cells which build bone by removing calcium and phosphates from the blood in the presence of the enzyme alkaline phosphatase secreted by osteoblasts • Osteocyte – mature cells found within compact bone (living bone)
Bone remodeling Occurs under the periosteum (White, double layered membrane) which is held to bone by Sharpey’s fibers
Osseous tissue • Compact bone (Lamellar bone) – Dense and hard; found on the external surfaces of bones • Spongy bone - contain trabeculae (little beams) which align along lines of stress; and open spaces filled with red or yellow marrow
Lamellar bone Osteon or Haversian System – structural unit of compact bone (cylindrical in shape) which bear weight - Lamella –each ring of an osteon - Haversian canal – contains blood vessels & nerve fibers which travel vertically in bone -Volkmann’s canal – contain blood vessels and nerve fibers which travel horizontally in bone
Lamellar bone • Lacuna – spaces found in compact bone occupied by osteocytes - Canaliculi – lateral canals which connect lacunae which allow osteocytes to diffuse nutrients and wastes into or out of bone tissue through gap junctions
Chemical composition - Hydroxyapatites 60-70% of bone weight mineral salts; mainly calcium phosphates *source of stiffness and compressive strength - Collagen fibers~ 10% of bone weight made up of glycoproteins *source of flexibility & tensile strength Aging causes decrease in collagen & an increase in fragility - Water~ 25-30% important contributor to bone strength
Bone markings Sites of tendon and ligament attachment Projections that help form joints Depressions and openings allowing blood vessels and nerve fibers to pass
Sites of muscle and ligament attachment - Tuberosity – large rounded projection - Crest – narrow prominent ridge - Trochanter – large, blunt, irregularly shaped process (Only found on the femur)
Sites of muscle and ligament attachment • Tubercle – small rounded projection or process - Epicondyle – raised area above a condyle - Spine – sharp, slender, often pointed projection - Process – any bony prominence
Projections that help form joints - Head – bony expansion carried on a narrow neck - Condyle – rounded articular projection - Ramus – arm like bar of bone
