1. Skeletal Cartilage
Contains no blood vessels or nerves
Surrounded by the perichondrium (dense irregular connective tissue) that resists outward expansion
Three types – hyaline, elastic, and fibrocartilage

2. Provides support, flexibility, and resilience
Hyaline Cartilage
Provides support, flexibility, and resilience
Is the most abundant skeletal cartilage
Is present in these cartilages:
Articular – covers the ends of long bones
Costal – connects the ribs to the sternum
Respiratory – makes up larynx, reinforces air passages
Nasal – supports the nose

3. Elastic Cartilage
Similar to hyaline cartilage, but contains elastic fibers
Found in the external ear and the epiglottis

4. Fibrocartilage
Highly compressed with great tensile strength
Contains collagen fibers
Found in menisci of the knee and in intervertebral discs

5. Calcification of cartilage occurs
Growth of Cartilage
Appositional – cells in the perichondrium secrete matrix against the external face of existing cartilage
Interstitial – lacunae-bound chondrocytes inside the cartilage divide and secrete new matrix, expanding the cartilage from within
Calcification of cartilage occurs
During normal bone growth
During old age

6. Bones and Cartilages of the Human Body
Figure 6.1

7. Classification of Bones
Axial skeleton – bones of the skull, vertebral column, and rib cage
Appendicular skeleton – bones of the upper and lower limbs, shoulder, and hip

8. Classification of Bones: By Shape
Long bones – longer than they are wide (e.g., humerus)
Figure 6.2a

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

10. Classification of Bones: By Shape
Flat bones – thin, flattened, and a bit curved (e.g., sternum, and most skull bones)
Figure 6.2c

11. Classification of Bones: By Shape
Irregular bones – bones with complicated shapes (e.g., vertebrae and hip bones)
Figure 6.2d

12. Function 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

13. Function of Bones
Mineral storage – reservoir for minerals, especially calcium and phosphorus
Blood cell formation – hematopoiesis occurs within the marrow cavities of bones

14. Bulges, depressions, and holes that serve as:
Bone Markings
Bulges, depressions, and holes that serve as:
Sites of attachment for muscles, ligaments, and tendons
Joint surfaces
Conduits for blood vessels and nerves

15. 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

16. 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

17. Bone Markings: Projections – 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

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

19. Gross Anatomy of Bones: Bone Textures
Compact bone – dense outer layer
Spongy bone – honeycomb of trabeculae filled with yellow bone marrow

20. Bone Markings
Table 6.1

21. Long bones consist of a diaphysis and an epiphysis Diaphysis
Structure of Long Bone
Long bones consist of a diaphysis and an epiphysis
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

22. 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

23. Structure of Long Bone
Figure 6.3

24. Structure of Long Bone
Figure 6.3a

25. Structure of Long Bone
Figure 6.3b

26. Structure of Long Bone
Figure 6.3c

27. Periosteum – double-layered protective membrane
Bone Membranes
Periosteum – double-layered protective membrane
Outer fibrous layer is dense regular connective tissue
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
Secured to underlying bone by Sharpey’s fibers

28. Bone Membranes
Endosteum – delicate membrane covering internal surfaces of bone

29. Structure of Short, Irregular, and Flat Bones
Thin plates of periosteum-covered compact bone on the outside with endosteum-covered spongy bone (diploë) on the inside
Have no diaphysis or epiphyses
Contain bone marrow between the trabeculae

30. Structure of a Flat Bone
Figure 6.4

31. Location of Hematopoietic Tissue (Red Marrow)
In infants
Found in the medullary cavity and all areas of spongy bone
In adults
Found in the diploë of flat bones, and the head of the femur and humerus

32. 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

33. 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

34. Microscopic Structure of Bone: Compact Bone
Figure 6.6a, b

35. Microscopic Structure of Bone: Compact Bone
Figure 6.6a

36. Microscopic Structure of Bone: Compact Bone
Figure 6.6b

37. Microscopic Structure of Bone: Compact Bone
Figure 6.6c

38. Chemical Composition of Bone: Organic
Osteoblasts – bone-forming cells
Osteocytes – mature bone cells
Osteoclasts – large cells that resorb or break down bone matrix
Osteoid – unmineralized bone matrix composed of proteoglycans, glycoproteins, and collagen

39. 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

40. Bone Development
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

41. 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

42. Intramembranous Ossification
Formation of most of the flat bones of the skull and the clavicles
Fibrous connective tissue membranes are formed by mesenchymal cells