2. Skeletal System
Anatomy

3. Bones of the Cranium
Some are thicker
than others!!!

4. Cranium Bones Parietal Bone Parietal Bone Frontal Bone Temporal Bone
Occipital Bone

5. Maxilla and Mandible ?
Maxilla
Mandible

6. Clavicle or Collarbone
The clavicle, or collar bone, holds the shoulder joint away from the rest of the upper body and is only as thick as your little finger.

7. Scapula
The scapula is located on the back side of the ribcage and helps provide part of the shoulder joint and movement for the arms.

8. Vertebral Column or Spinal Cord
1) The cervical region (neck bones) 
2) The thoracic region (what the ribs attach to)
3) The lumbar region (the lower part of the back) 

9. Coccyx and Sacrum

10. Humerus (Upper Arm Bone)

11. Radius and Ulna
Radius on Top
Ulna on Bottom

12. Carpals or (Wrist Bones)

13. Metacarpals (Top of Hands)

14. Phalanges (Little Fingers)

15. Rib Cage

16. Sternum (Breastbone)

17. Pelvis (Dancing Bone)

18. Femur (Largest Bone in the Body)

19. The Tibia and Fibula

20. Tarsals

21. Metatarsals

22. Phalanges

23. Calcaneous

24. The Skeletal System in Action !!

25. 5 Functions of the Skeletal System
1. Movement: Skeletal system provides points of attachment for muscles. Your legs and arms move when the muscles pull on the bones. 2. Support: The backbone is the main support center for the upper body. It holds your head up and protects your spinal cord.
Muscle attached to bones!!

26. 5 Functions of the Skeletal System
3. Protection: The bones of your skull protect your brain. Your ribs protect your lungs and heart from injury. 4. Makes Blood: Red and white blood cells are formed by tissue called marrow, which is in the center of the bone.

27. 5 Functions of the Skeletal System
5. Storage: Bones store minerals, such as calcium and phosphorus, for use by the body

28. Two Major Skeletal System Parts
Axial Skeleton (80): The axial skeleton includes the skull, hyoid bone, spine, ribs and sternum.
Appendicular Skeleton (126): The appendicular skeleton includes the appendages of the body, which are the shoulders, arms, hips, and legs.

30. 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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31. Skeletal System Bones Four basic bone shapes
1. Long- arms, legs and fingers
2. Short- wrist and ankles
3. Flat- skull and sternum
4. Irregular- spine

32. Classification of Bones
Long bones
Typically longer than wide
Have a shaft with heads at both ends
Contain mostly compact bone
Examples: Femur, humerus, radius, ulna, tibia, fibula, phalanges
Slide 5.4a
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33. Classification of Bones
Short bones
Generally cube-shape
Contain mostly spongy bone
Examples: Carpals, tarsals
Slide 5.4b
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34. Classification of Bones on the Basis of Shape
Figure 5.1
Slide 5.4c
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35. Classification of Bones
Flat bones
Broad and thin
Usually curved or flattened
Thin layers of compact bone around a layer of spongy bone
Examples: Skull, ribs, sternum, scapula, clavicles
Slide 5.5a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

36. Classification of Bones
Irregular bones
Irregular shape, often in groups
Do not fit into other bone classification categories
Example: Vertebrae, facial, pelvis, sacrum, coccyx
sesamoid “sesame seed shaped”- connect to tendons
ex. Patella, pisiform
Slide 5.5b
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37. Classification of Bones on the Basis of Shape
Figure 5.1
Slide 5.5c
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38. Bone Structure Typical Four Layers: Periosteum: Covers Bones
Compact Bone: Lies beneath the periosteum
Spongy Bone: Lies beneath the compact bone
Bone Marrow: Fills the gaps between the spongy bone

39. 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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40. 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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41. 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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42. 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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43. Microscopic Anatomy of Bone

44. Types of Bone Cells Osteocytes Osteoblasts Osteoclasts
Mature bone cells (bone maintenance), found within hard, rigid connective tissue
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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45. Microscopic Anatomy of Bone
Osteon (Haversian System)
A subunit of compact bone, circular arrangement of lacunae, lamellae, and a Haversian canal
Central Haversian/Osteonic canal
Opening in the center of an osteon, runs vertically in long bone
Carries blood vessels and nerves
Supply oxygen and nutrients for osteocytes
Slide 5.10a
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47. Microscopic Anatomy of Bone
Figure 5.3
Slide 5.10b
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48. Microscopic Anatomy of Bone
Lamella(e)
Rings of compact bone around central canal
Lacunae lie between rings
Lacuna(e)
Cavities containing osteocytes
Arranged in concentric rings
Figure 5.3
Slide 5.11a
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49. Microscopic Anatomy of Bone
Canaliculi (-us)
“little” canals
Contain cytoplasmic extension of osteocytes
Form a transport system- oxygen and nutrients from Haversian canal osteocytes via canaliculi
Figure 5.3
Slide 5.11b
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50. Microscopic Anatomy of Bone
Volkmann’s canal/Perforating Canal
Transverse canal- runs horizonatally in the long bone
Contains larger blood vessels
Connected to blood vessels in medullary cavity and in the Haversian Canal
Figure 5.3
Slide 5.10b
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51. Checkpoint 1 2 7 6 5 3 4

52. BONE GROWTH

53. 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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54. Long Bone Formation and Growth
Figure 5.4a
Slide 5.14a
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55. 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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56. Long Bone Formation and Growth
Figure 5.4a
Slide 5.14a
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57. 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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58. Long Bone Formation and Growth
Figure 5.4a
Slide 5.14a
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59. 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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60. Long Bone Formation and Growth
Figure 5.4b
Slide 5.14b
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61. 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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62. Long Bone Formation and Growth
Figure 5.4a
Slide 5.14a
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63. 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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64. Bone Growth: Intramembranous
“Between membranes”
Compact Bone
Spongy Bone
Trabeculae
Cross-section of a trabecula
Slide 5.12
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65. 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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66. 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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67. Common Types of Fractures
Table 5.2
Slide 5.17
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68. 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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69. 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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70. 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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