1. Do Now: 1. How many bones can you name in 60 seconds?
(Time yourself on the clock- Be Honest!
2. Make a guess for what 3 of the functions the skeletal system are.
3. If “osteo” means bone, then what is an osteocyte? What about an osteoblast?

2. Ch 5: The Skeletal System
Axial Skeleton, Skull, Vertebrae,
Appendicular Skeleton,
Skeletal Conditions
Joints

4. The Skeletal System 1. Bones (skeleton) 2. Joints 3. Cartilages
Parts of the skeletal system
1. Bones (skeleton)
2. Joints
3. Cartilages
4. Ligaments

5. Axial vs. Appendicular Divided into two divisions:
Axial skeleton – bones that form the longitudinal axis of the body
Example: skull, bony thorax, & vertebral column
Appendicular skeleton – bones of the limbs and girdles
Example: arms, shoulder, legs, hips

6. Functions of Bones 1. Support of the body 2. Protection of soft organs
3. Movement due to attached skeletal muscles
4. Storage of minerals and fats
5. Blood cell formation

7. Bones of the Human Body Two basic types of bone tissue Compact bone
The adult skeleton has 206 bones
Two basic types of bone tissue
Compact bone
Homogeneous
Spongy bone
Small needle-like pieces of bone
Many open spaces
Figure 5.2b

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

9. Classification of Bones
Short bones
Generally cube-shape
Contain mostly spongy bone
Examples: Carpals, tarsals

10. Classification of Bones
Flat bones
Thin and flattened
Usually curved
Thin layers of compact bone around a layer of spongy bone
Ex: Skull, ribs, sternum

11. Classification of Bones
Irregular bones
Irregular shape
Do not fit into other bone classification categories
Example: Vertebrae and hip

12. Classification of Bones on the Basis of Shape
Figure 5.1

13. Intro to Skeletal System Video
05 _Human Body
Skeletal System
2:30-5:30

14. Bone Markings Surface features of bones
Sites of attachments for muscles, tendons, and ligaments
Passages for nerves and blood vessels
Categories of bone markings
Projections and processes – go out
Depressions or cavities – go in

15. Gross Anatomy of a Long Bone
Diaphysis
Shaft
Composed of compact bone
Epiphysis
Ends of the bone
Composed mostly of spongy bone
Figure 5.2a

16. Structures of a Long Bone
Medullary cavity
Cavity of the shaft
Contains yellow marrow (mostly fat) in adults
Contains red marrow (for blood cell formation) in infants
Figure 5.2a

17. Structures of a Long Bone
Periosteum
Outside covering of the diaphysis
Fibrous connective tissue membrane
Arteries
Supply bone cells with nutrients
Figure 5.2c

18. Structures of a Long Bone
Articular cartilage
Covers the external surface of the epiphyses
Made of hyaline cartilage
Decreases friction at joint surfaces
Figure 5.2a

19. Microscopic Anatomy of Bone
Osteon (Haversian System)
A unit of bone
Central (Haversian) canal
Opening in the center of an osteon
Carries blood vessels and nerves
Perforating (Volkman’s) canal
Canal perpendicular to the central canal

20. Microscopic Anatomy of Bone
Figure 5.3

21. Microscopic Anatomy of Bone
Figure 5.3

22. Microscopic Anatomy of Bone
Lacunae
Cavities containing bone cells (osteocytes)
Arranged in concentric rings
Lamellae
Rings around the central canal
Sites of lacunae
Detail of Figure 5.3

23. Canaliculi Microscopic Anatomy of Bone Tiny canals
Radiate from the central canal to lacunae
Form a transport system
Detail of Figure 5.3

24. Types of Bone Cells Osteocytes Osteoblasts Osteoclasts
Mature bone cells
Osteoblasts
Bone-forming cells
Osteoclasts
Bone-destroying cells
Break down bone matrix for remodeling and release of calcium
Bone remodeling is a process by both osteoblasts and osteoclasts

25. Bone Structure

26. 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 isolated areas
Bridge of the nose
Parts of ribs
Joints

28. Long Bone Formation and Growth
Figure 5.4a

29. Bone Growth
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

30. Do Now What are the major parts of the skeletal system?
What are the four types of bones?
Why do you think there needs to be four different types of bones?

31. Bone Growth Bones are remodeled and lengthened until growth stops
Bones change shape somewhat
Bones grow in width

32. Long Bone Formation and Growth
Figure 5.4b

33. Remodeling The adult skeleton: maintains itself
replaces mineral reserves
Remodeling:
recycles and renews bone matrix
**** involves osteocytes, osteoblasts, and osteoclasts

34. Bone Remoldeling cont’d
Bone continually remodels, recycles, and replaces
Turnover rate varies
If deposition is greater than removal, bones get stronger
If removal is faster than replacement, bones get weaker

35. Bone Growth

36. Effects of Exercise on Bone
Mineral recycling allows bones to adapt to stress
Heavily stressed bones become thicker and stronger

37. Bone Degeneration Bone degenerates quickly
Up to 1/3 of bone mass can be lost in a few weeks of inactivity

38. Fractures-
cracks or breaks in bones
caused by physical stress

39. Bone Fractures A break in a bone
Healing time is approx. six to eight weeks for simple fractures
Healing time varies

40. Types of fractures Simple (closed) – clean break, does not break skin
Compound (open) – broken ends of the bone protrude through soft tissue and skin
Comminuted – bone breaks into many fragments

44. Bone Fragments Compression - bone is crushed
Depressed – broken bone is pressed inward
Impacted – broken bone end are forced into each other

45. Bone Fragments Spiral – ragged break caused by twisting forces
Greenstick – incomplete break, common in children
Figure 6–16 (9 of 9)

46. Common Types of Fractures
Table 5.2

47. Treatment
Two Steps:
1. Bone fractures are treated by reduction and then immobilization

48. Treatment continued 2. Realignment of the bone
Closed reduction – bone ends are forced back into normal position by doctor’s hands
Open reduction – surgery is needed to put bone ends together using pins or wires
3. After reduction, it is immobilized by a cast or traction to allow for healing

49. Repair of Bone Fractures
Hematoma (blood-filled swelling) is formed
Break is splinted by fibrocartilage to form a callus
Fibrocartilage callus is replaced by a bony callus
Bony callus is remodeled to form a permanent patch

50. Stages in the Healing of a Bone Fracture
Figure 5.5

51. Age and Bones Bones become thinner and weaker with age Osteopenia
weakening of bones’ mass
begins between ages 30 & 40
Bone mass loss per decade
Women lose 8%
Men lose 3%

52. Sec 1 Review

53. The End of Section 1
Assignments for this section: Review Questions from Notes Numbers 1-9 Ch5 Handout ｷPg1-2