1. Chapter 6: Skeletal System I

2. Bernard Siegfried Albinus 1697 – 1770 Famous for his drawings in the work entitled Tables of the Skeleton and Muscles of the Human Body published in 1747.

3. An example of Albinus’ drawings of the skeleton.

4. Figure 6.1 The bones and cartilages of the human skeleton. Axial skeleton Appendicular skeleton Hyaline cartilages Elastic cartilages Fibrocartilages Cartilages Bones of skeleton Epiglottis Larynx Trachea Cricoid cartilage Lung Respiratory tube cartilages in neck and thorax Thyroid cartilage Cartilage in external ear Cartilages in nose Articular Cartilage of a joint Costal cartilage Cartilage in Intervertebral disc Pubic symphysis Articular cartilage of a joint Meniscus (padlike cartilage in knee joint)

5. Figure 6.2 Classification of bones on the basis of shape. (a)Long bone (humerus) (b)Irregular bone (vertebra), right lateral view (d)Short bone (talus) (c)Flat bone (sternum)

6. Figure 6.3a The structure of a long bone (humerus of arm). Proximal epiphysis (a) Epiphyseal line Articular cartilage Periosteum Spongy bone Compact bone Medullary cavity (lined by endosteum) Diaphysis Distal epiphysis

7. (b) Articular cartilage Spongy bone Compact bone Figure 6.3b The structure of a long bone (humerus of arm).

8. (c) Yellow bone marrow Endosteum Compact bone Periosteum Perforating (Sharpey’s) fibers Nutrient arteries Figure 6.3c The structure of a long bone (humerus of arm).

9. Figure 6.4 Comparison of different types of bone cells. (a) Osteogenic cell(b) Osteoblast(c) Osteocyte Stem cell Mature bone cell that maintains the bone matrix Matrix-synthesizing cell responsible for bone growth (d) Osteoclast Bone-resorbing cell

10. Figure 6.5 Flat bones consist of a layer of spongy bone sandwiched between two thin layers of compact bone. Compact bone Trabeculae Spongy bone (diploë)

11. Figure 6.9 Endochondral ossification in a long bone. 12345 Bone collar forms around hyaline cartilage model. Cartilage in the center of the diaphysis calcifies and then develops cavities. The periosteal bud invades the internal cavities and spongy bone begins to form. The diaphysis elongates and a medullary cavity forms as ossification continues. Secondary ossification centers appear in the epiphyses in preparation for stage 5. The epiphyses ossify. When completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilages. Hyaline cartilage Area of deteriorating cartilage matrix Epiphyseal blood vessel Spongy bone formation Epiphyseal plate cartilage Secondary ossification center Blood vessel of periosteal bud Medullary cavity Articular cartilage Childhood to adolescence Birth Week 9 Month 3 Spongy bone Bone collar Primary ossification center

12. Figure 6.11 Long bone growth and remodeling during youth. Bone growth Bone remodeling Articular cartilage Epiphyseal plate Cartilage grows here. Cartilage is replaced by bone here. Cartilage grows here. Bone is resorbed here. Bone is resorbed here. Bone is added by appositional growth here. Cartilage is replaced by bone here.

13. Figure 6.12 Parathyroid hormone (PTH) control of blood calcium levels. Osteoclasts degrade bone matrix and release Ca 2+ into blood. Parathyroid glands Thyroid gland Parathyroid glands release parathyroid hormone (PTH). Stimulus Falling blood Ca 2+ levels PTH Calcium homeostasis of blood: 9–11 mg/100 ml BALANCE

14. Calcitonin

15. Figure 6.13 Bone anatomy and bending stress. Load here (body weight) Head of femur Compression here Point of no stress Tension here

16. Figure 6.14 Vigorous exercise can lead to large increases in bone strength. Cross- sectional dimension of the humerus Added bone matrix counteracts added stress (b) Serving arm (a) Nonserving arm

18. Steel “Bone Cages” used to lengthen legs. These were originally developed in the Soviet Union in the 1950s to treat dwarfism.

19. Twelve-year-old boy with pituitary gigantism measuring 6'5" with his mother. Note the coarse facial features and prominent jaw.

20. An example of untreated acromegaly.

21. Chelation Therapy – intravenous administration of chemicals designed to absorb toxic substances that have accumulated in the body. Most notably used for exposure to heavy metals such as lead or mercury.

22. Figure 6.15 Stages in the healing of a bone fracture. Hematoma External callus Bony callus of spongy bone Healed fracture New blood vessels Spongy bone trabecula Internal callus (fibrous tissue and cartilage) 1 A hematoma forms. 2 Fibrocartilaginous callus forms. 3 Bony callus forms. 4 Bone remodeling occurs.

23. Figure 6.16 The contrasting architecture of normal versus osteporotic bone.

24. Figure UN 6.1

25. Figure 6.17 Fetal primary ossification centers at 12 weeks. Parietal bone Radius Ulna Humerus Femur Occipital bone Clavicle Scapula Ribs Vertebra Ilium Tibia Frontal bone of skull Mandible

26. Table 6.2 Common Types of Fractures (1 of 3)

27. Table 6.2 Common Types of Fractures (2 of 3)

28. Table 6.2 Common Types of Fractures (3 of 3)