1. Bones and Skeletal Tissue
Chapter 6,7 & 8
Bones and Skeletal Tissue

2. Bones and Cartilages of the Human Body
Figure 6.1

3. How are bones classified?
Axial skeleton – bones of the skull, vertebral column, and rib cage
Appendicular skeleton – bones of the upper and lower limbs, shoulder, and hip

5. Long bones Long bones – longer than they are wide (e.g., humerus)
Figure 6.2a

6. Short bones Short bones Cube-shaped bones of the wrist and ankle
Bones that form within tendons (e.g., patella)
Figure 6.2b

7. Flat bones
Flat bones – thin, flattened, and a bit curved (e.g., sternum, and most skull bones)
Figure 6.2c

8. Irregular bones
Irregular bones – bones with complicated shapes (e.g., vertebrae and hip bones)
Figure 6.2d

9. What are the functions of bones?
Support – form the framework that supports the body and cradles soft organs
Protection – provide a protective case for the brain, spinal cord, and vital organs
Movement – provide levers for muscles
Mineral storage – reservoir for minerals, especially calcium and phosphorus
Blood cell formation – hematopoiesis occurs within the marrow cavities of bones

10. What is the Gross Anatomy of Bones?
Compact bone – dense outer layer
Spongy bone – honeycomb of trabeculae (little beams) filled with red bone marrow

12. What is the structure of a long bone?
Diaphysis
Tubular shaft that forms the axis of long bones
Composed of compact bone that surrounds the medullary cavity
Yellow bone marrow (fat) is contained in the medullary cavity

13. Structure of Long Bone Epiphyses Expanded ends of long bones
Exterior is compact bone, and the interior is spongy bone
Joint surface is covered with articular (hyaline) cartilage
Epiphyseal line separates the diaphysis from the epiphyses

14. Structure of Long Bone
Figure 6.3a,b

15. What are the bone membranes?
Periosteum – double-layered protective membrane
Outer fibrous layer is dense regular CT
Inner osteogenic layer is composed of osteoblasts and osteoclasts
Richly supplied with nerve fibers, blood, and lymphatic vessels, which enter the bone via nutrient foramina
Sharpey’s fibers: secures the underlying bone to the periosteum. They are tufts of collagen fibers.
Endosteum – delicate membrane covering internal surfaces of bone

16. Structure of Long Bone
Figure 6.3a, c

17. What is the structure of short, irregular, and flat bones?
Thin plates of periosteum-covered compact bone on the outside with endosteum-covered spongy bone on the inside
Have no diaphysis or epiphyses
Contain bone marrow between the trabeculae
Figure 6.4

18. Where is the location of hematopoietic tissue (Red Marrow)?
In infants
Found in the medullary cavity and all areas of spongy bone
In adults
Found in the middle of flat bones, and the head of the femur and humerus

19. What is microscopic structure of bone: compact bone?
Haversian system, or osteon – the structural unit of compact bone
Lamella – weight-bearing, column-like matrix tubes composed mainly of collagen
Haversian, or central canal – central channel containing blood vessels and nerves
Volkmann’s canals – channels lying at right angles to the central canal, connecting blood and nerve supply of the periosteum to that of the Haversian canal

20. Microscopic Structure of Bone: Compact Bone
Osteocytes – mature bone cells
Lacunae – small cavities in bone that contain osteocytes
Canaliculi – hairlike canals that connect lacunae to each other and the central canal

21. Microscopic Structure of Bone: Compact Bone
Figure 6.5a, b

23. What is the chemical composition of bone? (Organic)
Osteoblasts – bone-forming cells
Osteocytes – mature bone cells
Osteoclasts – large cells that reabsorb or break down bone matrix

24. Chemical Composition of Bone: Inorganic
Hydroxyapatites, or mineral salts
Sixty-five percent of bone by mass
Mainly calcium phosphates
Responsible for bone hardness and its resistance to compression

25. What are the types of markings found on bones?
Bulges, depressions, and holes that serve as:
Sites of attachment for muscles, ligaments, and tendons
Joint surfaces
Conduits for blood vessels and nerves

26. Bone Markings: Projections – Sites of Muscle and Ligament Attachment
Tuberosity – rounded projection
Crest – narrow, prominent ridge of bone
Trochanter – large, blunt, irregular surface
Line – narrow ridge of bone

27. Bone Markings: Projections – Sites of Muscle and Ligament Attachment
Tubercle – small rounded projection
Epicondyle – raised area above a condyle
Spine – sharp, slender projection
Process – any bony prominence

28. Bone Markings: Projections That Help to Form Joints
Head – bony expansion carried on a narrow neck
Facet – smooth, nearly flat articular surface
Condyle – rounded articular projection
Ramus – armlike bar of bone

29. Bone Markings: Depressions and Openings
Meatus – canal-like passageway
Sinus – cavity within a bone
Fossa – shallow, basinlike depression
Groove – furrow
Fissure – narrow, slitlike opening
Foramen – round or oval opening through a bone

30. How do bones develop?
Osteogenesis and ossification – the process of bone tissue formation, which leads to:
The formation of the bony skeleton in embryos
Bone growth until early adulthood
Bone thickness, remodeling, and repair

31. Formation of the Bony Skeleton
Begins at week 8 of embryo development
Intramembranous ossification – bone develops from a fibrous membrane
Endochondral ossification – bone forms by replacing hyaline cartilage

32. Intramembranous ossification

34. Functional Zones in Long Bone Growth
Growth zone – cartilage cells undergo mitosis, pushing the epiphysis away from the diaphysis
Transformation zone – older cells enlarge, the matrix becomes calcified, cartilage cells die, and the matrix begins to deteriorate
Osteogenic zone – new bone formation occurs

38. Long Bone Growth and Remodeling
Growth in length – cartilage continually grows and is replaced by bone as shown
Remodeling – bone is reabsorbed and added by appositional growth as shown
Figure 6.10

39. Fracture Repair