2. Chapter 6
The Skeletal System

3. Functions of Bone Supports and gives shape to the body
Protects internal organs
Helps make movements possible
Stores calcium & phosphorus
Hemopoiesis-formation of blood cells by red bone marrow

4. Types of Bones Long—example: humerus (upper arm)
Short—example: carpals (wrist)
Flat—example: frontal (skull)
Irregular—example: vertebrae (spinal cord)

5. Structure of Long Bones
Structural components
Diaphysis - shaft
Medullary cavity - contains yellow marrow
Epiphyses - ends of the bone; spongy bone contains red bone marrow
Articular cartilage—cushions and covers epiphyses
Periosteum—strong membrane covering bone except at joint surfaces
Endosteum—lines medullary cavity

7. Microscopic Structure of Bone and Cartilage
Bone types
Spongy
Texture results from needlelike threads of bone called trabeculae surrounded by a network of open spaces
Found in epiphyses of bones
Spaces contain red bone marrow
Compact
Structural unit is Haversian system (or osteon)—composed of concentric lamella, lacunae containing osteocytes and canaliculi, all covered by periosteum
(Cont’d…)

10. Microscopic Structure of Bone and Cartilage
(…Cont’d)
Cartilage
Cell type called chondrocyte
Matrix is gel-like and lacks blood vessels

11. Bone Formation and Growth
Sequence of development early—cartilage models replaced by calcified bone matrix
Osteoblasts form new bone, and osteoclasts resorb bone

13. Division of Skeleton Skeleton composed of the following
divisions and their subdivisions:
Axial skeleton
Skull
Spine
Thorax
Hyoid bone
(Cont’d…)

14. Division of Skeleton Appendicular skeleton
(…Cont’d)
Appendicular skeleton
Upper extremities, including shoulder girdle
Lower extremities, including hip girdle
Location and description of bones

18. 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
Pubic angle—angle between pubic bones of female generally wider

19. Joint (Articulations)
Kinds of joints
Synarthrosis (no movement)—fibrous connective tissue grows between articulating bones; for example, sutures of skull
Amphiarthrosis (slight movement)—cartilage connects articulating bones; for example, symphysis pubis
(Cont’d…)

20. Joint (Articulations)
(…Cont’d)
Diarthrosis (free movement)—most joints belong to this class
Structures of freely movable joints—joint capsule and ligaments holding 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
(Cont’d…)

22. Joint (Articulations)
(…Cont’d)
Types of freely movable (diarthrotic) joints
ball-and-socket (hip & shoulder)
hinge (finger, knee, elbow)
pivot (vertebrae--axis)
saddle (finger base--opposing the thumb to the fingers)
gliding: limited movement at superior & inferior art. processes(vertebrae)
condyloid: oval projection fits in an elliptical socket (wrist)

23. The End