1. Slide 1 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Chapter 6 The Skeletal System

2. Slide 2 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. FUNCTIONS OF THE SKELETAL SYSTEM  Supports and gives shape to the body  Protects internal organs  Helps make movements possible when bones at moveable joints are pulled by muscles  Stores calcium—hormones regulate calcium storage: calcitonin (CT) increases storage and parathyroid hormone (PTH) reduces stores of calcium  Hemopoiesis—blood cell formation in red bone marrow

3. Slide 3 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. TYPES OF BONES  Four major types, according to overall shape of the bone  Long—Example: humerus (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)

4. Slide 4 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. TYPES OF BONES (cont.)  Structure of long bones (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—thin membrane lining medullary cavity

5. Slide 5 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc.

6. Slide 6 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. TYPES OF BONES (cont.)  Structure of flat bones (Figure 6-2)  Spongy bone layer sandwiched between two compact bone layers  Diploe—spongy bone layer of a flat bone

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8. Slide 8 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. MICROSCOPIC STRUCTURE OF BONE AND CARTILAGE  Bone types (Figure 6-3)  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 (Figure 6-4) Structural unit is an osteon—calcified matrix arranged in multiple layers or rings called concentric lamella (Figure 6-4) Bone cells are called osteocytes and are found inside spaces called lacunae, which are connected by tiny tubes called canaliculi Bone cells are called osteocytes and are found inside spaces called lacunae, which are connected by tiny tubes called canaliculi

9. Slide 9 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc.

10. Slide 10 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc.

11. Slide 11 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. MICROSCOPIC STRUCTURE OF BONE AND CARTILAGE (cont.)  Cartilage (Figure 6-5)  Cell type called chondrocyte  Matrix is gel-like and lacks blood vessels

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13. Slide 13 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. BONE FORMATION AND GROWTH  Early bone development (before birth) consists of cartilage and fibrous structures  Osteoblasts form new bone, and osteoclasts reabsorb bone; osteocytes are inactive osteoblasts (Figure 6-6)  Cartilage models gradually replaced by calcified bone matrix—process called endochondral ossification (Figures 6-7 and 6-8)

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17. Slide 17 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. DIVISIONS OF SKELETON Skeleton composed of the following divisions and subdivisions: Skeleton composed of the following divisions and subdivisions:  Axial skeleton  Skull  Spine (vertebral column)  Thorax  Hyoid bone  Appendicular skeleton  Upper extremities, including shoulder (pectoral) girdle  Lower extremities, including hip (pelvic) girdle  Location and description of bones—see Figures 6-9 to 6-20 and Tables 6-2 to 6-6

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31. Slide 31 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. 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 6-21)  Pubic angle—angle between pubic bones of female generally wider

32. Slide 32 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc.

33. Slide 33 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. JOINT (ARTICULATIONS)  Every bone except the hyoid (which anchors the tongue) connects to at least one other bone  Kinds of joints (Figures 6-22 to 6-24)  Synarthroses (no movement)—fibrous connective tissue grows between articulating bones; example: sutures of skull  Amphiarthroses (slight movement)—cartilage connects articulating bones; example: symphysis pubis

34. Slide 34 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. JOINT (ARTICULATIONS) (cont.)  Kinds of joints (cont.)  Diarthroses (free movement)—most joints belong to this class Structure Structure  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  Synovial membrane—lines joint capsule and secretes lubricating fluid  Joint cavity—space between joint ends of bones  Bursa—fluid-filled pouch that absorbs shock; inflammation of bursa is called bursitis Functions of freely moveable joints—ball-and-socket, hinge, pivot, saddle, gliding, and condyloid—allow different kinds of movements determined by the structure of each joint (Table 6-7) Functions of freely moveable joints—ball-and-socket, hinge, pivot, saddle, gliding, and condyloid—allow different kinds of movements determined by the structure of each joint (Table 6-7)

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