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Bones. Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. The.

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Presentation on theme: "Bones. Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. The."— Presentation transcript:

1 Bones

2 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. The bones and cartilages of the human skeleton Epiglottis Larynx Trachea Lung Respiratory tube cartilages in neck and thorax = Hyaline cartilages Key: = Fibrocartilages = Elastic cartilages = Bones of axial skeleton = Bones of appendicular skeleton 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)

3 Hyaline cartilage (a)H [amp ] E ×150 (b) Thin epoxy resin section, toluidine blue ×1200; (b)Cb chondroblasts Cc chondrocytes L lipid droplet M cartilage matrix N nucleus P perichondrium

4 Fibrocartilage H [amp ] E/Alcian blue ×320

5 Elastic cartilage Elastic van Gieson ×128

6 Cortical (compact) bone Ground sections, unstained (a)TS ×80 (b) TS ×600 (c) LS ×150; C bone canaliculi (b) H1 and H2 Haversian systems HC Haversian canals I interstitial system (c)L lacunae V Volkmann's canal

7 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Classification of bones on the basis of shape (a) (b) (d) (c) Long bone (humerus) Short bone (triquetral) Irregular bone (vertebra), left lateral view Flat bone (sternum)

8 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. The structure of a long bone (humerus of arm) (b) (c)(a) Proximal epiphysis Articular cartilage Yellow bone marrow Endosteum Epiphyseal line Spongy bone Periosteum Compact bone Medullary cavity Spongy bone Compact bone Articular cartilage Compact bone Periosteum Perforating (Sharpey’s) fibers Nutrient arteries Diaphysis Distal epiphysis

9 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. A single osteon Lamellae Collagen fibers Twisting force Nerve fiber Vein Artery with capillaries Structures in the central canal

10 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Microscopic anatomy of compact bone (a) (b) (c) Perforating (Sharpe’s) fibers Compact bone Periosteal blood vessel Periosteum Lacuna Blood vessel Endosteum lining bony canals and covering trabeculae Central (Haversian) canal Spongy bone Blood vessel continues into medullary cavity containing marrow Central (Haversian) canal Canaliculus Lacuna Lamella Osteocyte Osteon (Haversian system) Circumferential lamellae Lamellae Osteon Interstitial lamellae Central canal Perforating (Volkmann’s) canal

11 Periosteum (a) Inactive: H [amp ] E ×128 (b) Active: H [amp ] E ×200

12 Ossification Intramembranous: patelas Endochondral: epiphysis

13 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Intramembranous ossification Mesenchymal cell Collagen fiber Ossification center Osteoid Osteoblast Osteoid Osteocyte Newly calcified bone matrix Osteoblast An ossification center appears in the fibrous connective tissue membrane. Selected centrally located mesenchymal cells cluster and differentiate into osteoblasts, forming an ossification center. Bone matrix (osteoid) is secreted within the fibrous membrane. Osteoblasts begin to secrete osteoid, which is mineralized within a few days. Trapped osteoblasts become osteocytes. 1 2

14 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Intramembranous ossification (continued) Mesenchyme Condensing to form the periosteum Blood vessel Trabecula of woven bone Fibrous periosteum Osteoblast Plate of compact bone Diploë (spongy bone) cavities contain red marrow Woven bone and periosteum form. Accumulating osteoid is laid down between embryonic blood vessels, which form a random network. The result is a network (instead of lamellae) of trabeculae. Vascularized mesenchyme condenses on the external face of the woven bone and becomes the periosteum. Bone collar of compact bone forms and red marrow appears. Trabeculae just deep to the periosteum thicken, forming a woven bone collar that is later replaced with mature lamellar bone. Spongy bone (diploë), consisting of distinct trabeculae, persists internally and its vascular tissue becomes red marrow. 3 4

15 Intramembranous ossification H [amp ] E ×75; B woven bone M primitive mesenchyme Ob osteoblas

16 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Endochondral ossification in a long bone Formation of bone collar around hyaline cartilage model. Hyaline cartilage Cavitation of the hyaline carti- lage within the cartilage model. Invasion of internal cavities by the periosteal bud and spongy bone formation. Formation of the medullary cavity as ossification continues; appearance of sec- ondary ossification centers in the epiphy- ses in preparation for stage 5. Ossification of the epiphyses; when completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilages. Deteriorating cartilage matrix Epiphyseal blood vessel Spongy bone formation Epiphyseal plate cartilage Secondary ossificaton center Blood vessel of periosteal bud Medullary cavity Articular cartilage Spongy bone Primary ossification center Bone collar

17 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Growth in length of a long bone Calcified cartilage spicule Osseous tissue (bone) covering cartilage spicules Growth (proliferation) zone Cartilage cells undergo mitosis Resting (quiescent) zone Hypertrophic zone Older cartilage cells enlarge Ossification (osteogenic) zone New bone formation is occurring Calcification zone Matrix becomes calcified; cartilage cells die; matrix begins deteriorating Osteoblast depositing bone matrix

18 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Long bone growth and remodeling during youth Growth Bone grows in length because: Cartilage grows here Cartilage grows here Cartilage replaced by bone here Cartilage replaced by bone here Remodeling Growing shaft is remodeled by: Articular cartilage Bone resorbed here Bone added by appositional growth here Bone resorbed here Epiphyseal plate

19

20 Epiphysial growth plate H [amp ] E/Alcian blue ×40

21 Endochondral ossification - metaphysis H [amp ] E/Alcian blue ×198

22 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Stages in the healing of a bone fracture Hematoma External callus Bony callus of spongy bone Healed fracture New blood vessels Spongy bone trabeculae Internal callus (fibrous tissue and cartilage) Hematoma formation Fibrocartilaginous callus formation Bony callus formation Bone remodeling

23 Bone remodelling and repair H [amp ] E ×480; B bone D cartilage degeneration E epiphyseal cartilage GP epiphysial growth plate H hypertrophy zone M maturation zone O osteogenic zone Ob osteoblast Oc osteoclast P proliferative zone R reserve cartilage zone SC secondary ossification centre V blood vessels WB woven bone

24 Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Bone anatomy and stress Load here (body weight) Head of femur Compression here Point of no stress Tension here


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