Chapter 6 The Skeletal System

Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 2 FUNCTIONS OF THE SKELETAL SYSTEM  Supports and gives shape to the body  Protects internal organs  Helps make movements possible  Stores calcium  Hemopoiesis, or blood cell formation

Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 3 TYPES OF BONES  Four major types, according to overall shape of the bone  Long—Example: humerus (upper arm)  Short—Example: carpals (wrist)  Flat—Example: frontal (skull)  Irregular—Example: vertebrae (spinal cord)  Some also recognize a sesamoid (round) bone category  Example: patella (kneecap)

Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 4 STRUCTURE OF LONG BONES  Structural components (Figure 6-1)  Diaphysis or shaft—hollow tube of hard compact bone  Medullary cavity—hollow area inside diaphysis bone that contains yellow marrow  Epiphyses, or ends of the bone—spongy bone that contains red bone marrow  Articular cartilage—covers epiphyses and functions as a cushion  Periosteum—strong membrane covering bone everywhere except at joint surfaces  Endosteum—lining of medullary cavity

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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 6 MICROSCOPIC STRUCTURE OF BONE AND CARTILAGE  Bone types (Figure 6-2)  Spongy Texture results from needlelike threads of bone called trabeculae surrounded by a network of open spaces Texture results from needlelike threads of bone called trabeculae surrounded by a network of open spaces Found in epiphyses of bones Found in epiphyses of bones Spaces contain red bone marrow Spaces contain red bone marrow  Compact Structural unit is an osteon—calcified matrix arranged in multiple layers or rings called concentric lamella Structural unit is an osteon—calcified matrix arranged in multiple layers or rings called concentric lamella Composed of osteocytes, lacunae, and canaliculi Composed of osteocytes, lacunae, and canaliculi Covered by periosteum Covered by periosteum

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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 8 MICROSCOPIC STRUCTURE OF BONE AND CARTILAGE  Cartilage (Figure 6-4)  Cell type called chondrocyte  Matrix is gel-like and lacks blood vessels

Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 9 BONE FORMATION AND GROWTH (Figures 6-5 and 6-6)  Early bone development (before birth) consists of cartilage and fibrous structures  Cartilage models gradually replaced by calcified bone matrix—process called endochondral ossification  Osteoblasts form new bone, and osteoclasts resorb bone

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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 11 DIVISIONS OF SKELETON Skeleton composed of the following divisions and their subdivisions:  Axial skeleton  Skull  Spine (vertebral column)  Thorax  Appendicular skeleton  Upper extremities, including shoulder (pectoral) girdle  Lower extremities, including hip (pelvic) girdle  Location and description of bones—see Figures 6-7 to 6-17 and Tables 6-2 to 6-6

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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 22 DIFFERENCES BETWEEN A MAN’S AND A WOMAN’S SKELETON  Size—male skeleton generally larger  Shape of pelvis—male pelvis deep and narrow; female pelvis broad and shallow  Size of pelvic inlet—female pelvic inlet generally wider, normally large enough for baby’s head to pass through it (Figure 6- 18)  Pubic angle—angle between pubic bones of female generally wider

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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 24 JOINT (ARTICULATIONS) Every bone except the hyoid (which anchors the tongue) connects to at least one other bone  Kinds of joints (Figures 6-19 to 6-21)  Synarthroses (no movement)—fibrous connective tissue grows between articulating bones; example: sutures of skull  Amphiarthroses (slight movement)—cartilage connects articulating bones; example: symphysis pubis  Diarthroses (free movement)—most joints belong to this class Structures of freely movable joints—joint capsule and ligaments hold adjoining bones together but permit movement at joint Structures of freely movable joints—joint capsule and ligaments hold adjoining bones together but permit movement at joint Articular cartilage—covers joint ends of bones and absorbs joints Articular cartilage—covers joint ends of bones and absorbs joints Synovial membrane—lines joint capsule and secretes lubricating fluid Synovial membrane—lines joint capsule and secretes lubricating fluid Joint cavity—space between joint ends of bones Joint cavity—space between joint ends of bones  Types of freely movable joints—ball-and-socket, hinge, pivot, saddle, gliding, and condyloid

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