1. The Skeletal System
Chapter 6

2. Skeletal System
Introduction
Functions of the skeleton
Framework of bones
The skeleton through life

3. Functions of the Skeleton
Support
Protection
Movement
Storage areas
Minerals
Lipids
Hemopoiesis
Red marrow

4. Histology of Bones Bone = osseous tissue (connective tissue)
Intercellular substance
Hydroxyapatite crystals
Collagenous fibers

5. Human Anatomy, 3rd edition
Anatomy of a Long Bone
Diaphysis – shaft
Epiphysis – extremity of bone
Articular cartilage – covers epiphysis
Periosteum – covering around surface of bone
Medullary cavity – marrow cavity in diaphysis
Endosteum – lines medullary cavity
Human Anatomy, 3rd edition
Prentice Hall, © 2001

6. Human Anatomy, 3rd edition
The Periosteum
Two layers
Fibrous layer
Osteogenic layer
Osteoblasts
Human Anatomy, 3rd edition
Prentice Hall, © 2001

7. Human Anatomy, 3rd edition
The Endosteum
Single layer
Osteoclasts
Osteoblasts
Human Anatomy, 3rd edition
Prentice Hall, © 2001

8. Structure of Bone Tissue
Pores
Living cells
Channels for blood vessels
Decrease weight of bone
Degree of porosity
Spongy (cancellous) bone
Compact bone
Human Anatomy, 3rd edition
Prentice Hall, © 2001

9. Human Anatomy, 3rd edition
Compact Bone
Haversian system (Osteon)
Volkmann’s canals
Haversian canals
Lamellae
Lacunae
Canaliculi
Human Anatomy, 3rd edition
Prentice Hall, © 2001

10. Human Anatomy, 3rd edition
Spongy Bone
Composed of trabeculae
Penetrated by blood vessels from periosteum
Human Anatomy, 3rd edition
Prentice Hall, © 2001

11. Ossification Embryo skeleton 2 types Begins as cartilage & membrane
Bone formation begins about 6 weeks after fertilization
2 types
Intramembranous ossification
Endochondral ossification

12. Ossification
1st stage – embryonic mesenchyme cells migrate into future bone sites
Become chondroblasts or
Become osteoblasts

13. Intramembranous Ossification
Mostly in flat bones
Osteoblasts in the fibrous membrane secrete intercellular substances (matrix)
Matrix becomes mineralized
Formation of spongy bone
Original layer of connective tissue remains as periosteum

14. Intramembranous Ossification
FG05_05A.JPG
Title: A Three-Dimensional View of the Intramembranous Ossification
Notes: Stepwise formation of intramembranous bone from mesenchymal cell aggregation to spongy bone; spongy bone might form compact bone.
Keywords: ossification, osteocyte, matirx, osteoblast, osteod, mesenchyme, stem cell, spicules, osteoblast

15. Intramembranous Ossification
FG05_05B.JPG
Title: A Three-Dimensional View of the Intramembranous Ossification
Notes: Stepwise formation of intramembranous bone from mesenchymal cell aggregation to spongy bone; spongy bone might form compact bone.
Keywords: ossification, osteocyte, matirx, osteoblast, osteod, mesenchyme, stem cell, spicules, osteoblast

16. Intramembranous Ossification
FG05_05C.JPG
Title: A Three-Dimensional View of the Intramembranous Ossification
Notes: Stepwise formation of intramembranous bone from mesenchymal cell aggregation to spongy bone; spongy bone might form compact bone.
Keywords: ossification, osteocyte, matirx, osteoblast, osteod, mesenchyme, stem cell, spicules, osteoblast

17. Endochondral Ossification
Occurs within a hyaline cartilage model
Occurs in most bones of the body
Periosteum forms at about week 8
Calcification begins in center of diaphysis
Primary ossification center
Secondary ossification centers at epiphyses
Medullary cavity forms

18. Endochondral Ossification
FG05_07A.JPG
Title: Endochondral Ossification
Notes: Steps in the formation of a long bone.
Keywords: chondrocytes, matrix, epiphysis, diaphysis, osteogenic, marrow, periosteal, spongy bone, metaphysis, ossification

19. Endochondral Ossification
FG05_07B.JPG
Title: Endochondral Ossification
Notes: Light micrograph showing the zones of cartilage ad the advancing osteoblasts at a epiphyseal plate.
Keywords: osteoblasts, osteoid, marrow cavity, epiphyseal cartilage matrix, cartilage cells, zone of proliferation, zone of hypertrophy

20. Fetus. 10 weeks

21. Fetus, 16 weeks

22. Remaining Cartilage Articular cartilage Epiphyseal plate
Bone grows in length

23. Homeostasis Remodeling Factors affecting bone growth
Different rates in body
Balance between osteoclasts and osteoblasts
Factors affecting bone growth
Calcium & phosphorus in diet
Vitamins A, C, & D
Hormones
Growth hormone, thyroxine
Calcitonin
Parathyroid hormone
Sex hormones

24. Fracture Repair Hematoma formation
Formation of fibrocartilagenous callus
Formation of bony callus
Remodeling of bony callus

25. Fracture Repair FG05_11.JPG Title: Fracture Repair
Notes: Steps involved in the repair of a fracture.
Keywords: spongy bone, callus, periosteum, hematoma

26. Disorders
Vitamin deficiencies
Scurvy
Rickets
Osteoporosis

27. Scurvy

28. Scurvy Blood Vessels

29. Rickets

30. Osteoporosis