1. Essentials of Anatomy and Physiology
Fifth edition
Seeley, Stephens and Tate
Skeletal System, Bones and Joints
Slide 2.1
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2. The Skeletal System Components of the skeletal system Bones (skeleton)
Joints
Cartilages
Ligaments
Slide 5.1
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3. The Skeletal System Two subdivisions Axial skeleton
Appendicular skeleton
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4. Appendicular skeleton
Axial skeleton
Skull
Auditory ossicles and hyoid bone
Vertebral column
Thoracic cage
Appendicular skeleton
Pectoral and pelvic girdles
Upper and lower limbs

5. Figure 7.1b

6. Functions of Bones Support of the body Protection of soft organs
Movement due to attached skeletal muscles: “passive”
Storage of minerals and fats
Blood cell formation
Slide 5.2
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7. Bones of the Human Body The skeleton has ~206 bones
Two basic types of bone tissue
Compact bone
Dense
Spongy bone
Small needle-like pieces of bone
Many open spaces
Figure 5.2b
Slide 5.3
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8. Classification of Bones
Long bones
Typically longer than wide
Have a shaft with heads at both ends
Contain mostly compact bone
Examples: Femur, humerus
Slide 5.4a
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9. Classification of Bones
Short bones
Generally cube-shape
Contain mostly spongy bone
Examples: Carpals, tarsals
Slide 5.4b
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10. Classification of Bones on the Basis of Shape
Figure 5.1
Slide 5.4c
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11. Classification of Bones
Flat bones
Thin and flattened
Usually curved
Thin layers of compact bone around a layer of spongy bone
Examples: Skull, ribs, sternum
Slide 5.5a
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12. Classification of Bones
Irregular bones
Irregular shape
Do not fit into other bone classification categories
Example: Vertebrae and hip
Slide 5.5b
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13. Classification of Bones on the Basis of Shape
Figure 5.1
Slide 5.5c
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14. Gross Anatomy of a Long Bone
Diaphysis
Shaft
Made of compact bone
Epiphysis
Expanded ends of long bones
Covered with dense bone
Internal structure is spongy bone
Figure 5.2a
Slide 5.6
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15. Structures of a Long Bone
Periosteum
Outside covering of the diaphysis
Fibrous connective tissue membrane
Arteries
Supply bone cells with nutrients
Figure 5.2c
Slide 5.7
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16. Structures of a Long Bone
Articular cartilage
Covers surface of epiphyses
Hyaline cartilage
Decreases friction at joint surfaces
Figure 5.2a
Slide 5.8a
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17. Structures of a Long Bone
Medullary cavity
Cavity in shaft
Contains yellow marrow in adults
Contains red marrow in infants
Figure 5.2a
Slide 5.8b
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18. Microscopic Anatomy of Bone
Osteon (Haversian System)
A subunit of compact bone
Central (Haversian) canal
Opening in the center of an osteon
Carries blood vessels and nerves
Slide 5.10a
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19. Microscopic Anatomy of Bone
Figure 5.3
Slide 5.10b
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20. Microscopic Anatomy of Bone
Lacuna(e)
Cavities containing osteocytes
Arranged in concentric rings
Lamella(e)
Rings of compact bone
Lacunae lie between rings
Figure 5.3
Slide 5.11a
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21. Microscopic Anatomy of Bone
Canaliculi (-us)
Tiny canals
Radiate from the central canal to lacunae
Form a transport system
Figure 5.3
Slide 5.11b
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22. Types of Bone Cells Osteocytes Osteoblasts Osteoclasts
Mature bone cells (bone maintenance)
Osteoblasts
Bone-forming cells
Osteoclasts
Bone-destroying cells
Break down bone matrix for remodeling and release of calcium
Slide 5.15
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23. Bone Growth: Endochondral
1) A cartilage model is produced by chondrocytes
It is surrounded by perichondrium, a membrane
2) A bone “collar” is produced by osteocytes
The perichondrium of the diaphysis is now termed periosteum
Slide 5.13a
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24. Long Bone Formation and Growth
Figure 5.4a
Slide 5.14a
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25. Bone Growth: Endochondral
3) Chondrocytes hypertrophy (enlarge) and cartilage is calcified
4) A primary ossification center forms
Blood vessels and osteoblasts invade the calcified cartilage
Osteoblasts lay down bone matrix
Trabeculae are formed
Slide 5.13a
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26. Long Bone Formation and Growth
Figure 5.4a
Slide 5.14a
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27. Bone Growth: Endochondral
5) Around the time of birth, secondary ossification centers form in the epiphyses
Bone formation is incomplete at birth
The skeleton is not complete until the late teens (females) or early twenties (males)
Slide 5.13a
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28. Long Bone Formation and Growth
Figure 5.4a
Slide 5.14a
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29. Bone Growth: Endochondral
Epiphyseal plates allow for growth of long bone during childhood
New cartilage is continuously formed
Older cartilage becomes ossified
Cartilage is broken down
Bone replaces cartilage
Slide 5.13a
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30. Long Bone Formation and Growth
Figure 5.4b
Slide 5.14b
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31. Bone Growth: Endochondral
Bones are remodeled and lengthened until growth stops
Bones change shape (how?? DNA!!!)
Bones grow in width (osteoblasts)
Bones are remodeled by osteoclasts
Slide 5.13b
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32. Long Bone Formation and Growth
Figure 5.4a
Slide 5.14a
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33. Changes in the Human Skeleton
In embryos, the skeleton is primarily hyaline cartilage
During development, much of this cartilage is replaced by bone
Cartilage remains in:
Anterior portion of the nose
Parts of ribs
Joints
Slide 5.12
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34. Bone Growth: Intramembranous
“Between membranes”
Compact Bone
Spongy Bone
Trabeculae
Cross-section of a trabecula
Slide 5.12
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35. Bone Formation: Intramembranous
Membranous bones are incomplete at birth
Fontanelles: regions of the skull that remain as membranes
“Little fountains”
Bone formation complete by age ~2
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36. Bone Fractures A break in a bone Types of bone fractures
Closed (simple) fracture –does not penetrate the skin
Open (compound) fracture – broken bone penetrates through the skin
Bone fractures are treated by reduction and immobilization
Slide 5.16
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37. Common Types of Fractures
Table 5.2
Slide 5.17
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38. Repair of Bone Fractures
Hematoma (blood clot) is formed
Break is splinted by fibrocartilage
forms a callus (chondroblasts, other cells, and vessels)
Callus is replaced by a bone (osteoblasts)
Bony callus is remodeled (osteoclasts)
Slide 5.18
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39. Repair of Bone Fractures
Fracture Repair
Hematoma formation (A)
Callus formation (B)
Bone replacement (C )
Bone remodeling (D) A B C D
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40. Bone Fractures: Osteoporosis
Most common in post-menopausal women
Also occurs in males
Due to decrease in estrogen levels
Estrogen receptors on osseous tissue affect calcium deposition
Bone becomes porous, brittle
Weight-bearing exercise, calcium supplements, estrogen will help prevent osteoporosis
Slide 5.16
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