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Chapter Opener 6 © 2013 Pearson Education, Inc. Figure 6.1 The bones and cartilages of the human skeleton. Cartilage in external ear Cartilage in intervertebral disc Cartilages in nose Articular cartilage of a joint Costal cartilage Epiglottis Thyroid cartilage Cricoid cartilage Larynx Trachea Lung Respiratory tube cartilages in neck and thorax Pubic symphysis Meniscus (padlike cartilage in knee joint) Articular cartilage of a joint © 2013 Pearson Education, Inc. Bones of skeleton Axial skeleton Appendicular skeleton Cartilages Hyaline cartilages Elastic cartilages Fibrocartilages Figure 6.2 Classification of bones on the basis of shape. Flat bone (sternum) Long bone (humerus) Irregular bone (vertebra), right lateral view © 2013 Pearson Education, Inc. Short bone (talus) Figure 6.2a Classification of bones on the basis of shape. Long bone (humerus) © 2013 Pearson Education, Inc. Figure 6.2b Classification of bones on the basis of shape. Irregular bone (vertebra), right lateral view © 2013 Pearson Education, Inc. Figure 6.2c Classification of bones on the basis of shape. Flat bone (sternum) © 2013 Pearson Education, Inc. Figure 6.2d Classification of bones on the basis of shape. Short bone (talus) © 2013 Pearson Education, Inc. Figure 6.3 Flat bones consist of a layer of spongy bone sandwiched between two thin layers of compact bone. Spongy bone (diploë) Compact bone Trabeculae of spongy bone © 2013 Pearson Education, Inc. Figure 6.4 The structure of a long bone (humerus of arm). Articular cartilage Proximal epiphysis Compact bone Spongy bone Epiphyseal line Periosteum Endosteum Endosteum Compact bone Medullary cavity (lined by endosteum) Diaphysis Yellow bone marrow Compact bone Periosteum Perforating (Sharpey’s) fibers Nutrient arteries Distal epiphysis © 2013 Pearson Education, Inc. Figure 6.4a The structure of a long bone (humerus of arm). Articular cartilage Proximal epiphysis Spongy bone Epiphyseal line Periosteum Compact bone Medullary cavity (lined by endosteum) Diaphysis Distal epiphysis © 2013 Pearson Education, Inc. Figure 6.4b The structure of a long bone (humerus of arm). Articular cartilage Compact bone Spongy bone Endosteum © 2013 Pearson Education, Inc. Figure 6.4c The structure of a long bone (humerus of arm). Endosteum Yellow bone marrow Compact bone Periosteum Perforating (Sharpey’s) fibers Nutrient arteries © 2013 Pearson Education, Inc. Figure 6.5 Comparison of different types of bone cells. Osteogenic cell Stem cell © 2013 Pearson Education, Inc. Osteoblast Matrix-synthesizing cell responsible for bone growth Osteocyte Mature bone cell that monitors and maintains the mineralized bone matrix Osteoclast Bone-resorbing cell Figure 6.5a Comparison of different types of bone cells. Osteogenic cell Stem cell © 2013 Pearson Education, Inc. Figure 6.5b Comparison of different types of bone cells. Osteoblast Matrix-synthesizing cell responsible for bone growth © 2013 Pearson Education, Inc. Figure 6.5c Comparison of different types of bone cells. Osteocyte Mature bone cell that monitors and maintains the mineralized bone matrix © 2013 Pearson Education, Inc. Figure 6.5d Comparison of different types of bone cells. Osteoclast Bone-resorbing cell © 2013 Pearson Education, Inc. Table 6.1 Bone Markings (1 of 2) © 2013 Pearson Education, Inc. Table 6.1 Bone Markings (2 of 2) © 2013 Pearson Education, Inc. Figure 6.6 A single osteon. Artery with capillaries Structures in the central canal Vein Nerve fiber Lamellae Collagen fibers run in different directions Twisting force © 2013 Pearson Education, Inc. Figure 6.7 Microscopic anatomy of compact bone. Compact bone Spongy bone Central (Haversian) canal Perforating (Volkmann’s) canal Endosteum lining bony canals and covering trabeculae Osteon (Haversian system) Circumferential lamellae Lamellae Nerve Vein Artery Canaliculi Osteocyte in a lacuna © 2013 Pearson Education, Inc. Perforating (Sharpey’s) fibers Periosteal blood vessel Periosteum Lamellae Central canal Lacunae Interstitial Lacuna lamella (with osteocyte) Figure 6.7a Microscopic anatomy of compact bone. Compact bone Spongy bone Central (Haversian) canal Perforating (Volkmann’s) canal Endosteum lining bony canals and covering trabeculae Osteon (Haversian system) Circumferential lamellae Lamellae © 2013 Pearson Education, Inc. Perforating (Sharpey’s) fibers Periosteal blood vessel Periosteum Figure 6.7b Microscopic anatomy of compact bone. Nerve Vein Artery Canaliculi Osteocyte in a lacuna © 2013 Pearson Education, Inc. Lamellae Central canal Lacunae Figure 6.7c Microscopic anatomy of compact bone. Lamellae Central canal Lacunae Interstitial Lacuna lamella (with osteocyte) © 2013 Pearson Education, Inc. Figure 6.8 Endochondral ossification in a long bone. Week 9 Month 3 Birth Secondary ossification center Epiphyseal blood vessel Area of deteriorating cartilage matrix Hyaline cartilage Spongy bone formation Bone collar Primary ossification center 1 Bone collar forms around the diaphysis of the hyaline cartilage model. © 2013 Pearson Education, Inc. Childhood to adolescence Articular cartilage Spongy bone Epiphyseal plate cartilage Medullary cavity Blood vessel of periosteal bud 2 Cartilage in the center of the diaphysis calcifies and then develops cavities. 3 The periosteal bud invades the internal cavities and spongy bone forms. 4 The diaphysis elongates and a medullary cavity forms. Secondary ossification centers appear in the epiphyses. 5 The epiphyses ossify. When completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilages. Figure 6.8 Endochondral ossification in a long bone. (1 of 5) Week 9 Hyaline cartilage Bone collar Primary ossification center 1 Bone collar forms around the © 2013 Pearson Education, Inc. diaphysis of the hyaline cartilage model. Figure 6.8 Endochondral ossification in a long bone. (2 of 5) Area of deteriorating cartilage matrix 2 Cartilage in the center of the diaphysis calcifies and then develops cavities. © 2013 Pearson Education, Inc. Figure 6.8 Endochondral ossification in a long bone. (3 of 5) Month 3 Spongy bone formation Blood vessel of periosteal bud 3 The periosteal bud invades the internal cavities and spongy bone forms. © 2013 Pearson Education, Inc. Figure 6.8 Endochondral ossification in a long bone. (4 of 5) Birth Epiphyseal blood vessel Secondary ossification center Medullary cavity 4 The diaphysis elongates and a medullary cavity forms. Secondary ossification centers appear in the epiphyses. © 2013 Pearson Education, Inc. Figure 6.8 Endochondral ossification in a long bone. (5 of 5) Childhood to adolescence Articular cartilage Spongy bone Epiphyseal plate cartilage The epiphyses ossify. When completed, hyaline cartilage remains only in the epiphyseal plates and articular © 2013 Pearson Education, Inc. cartilages. 5 Figure 6.9 Intramembranous ossification. Mesenchymal cell Osteoblast Collagen fibril Osteoid Ossification center Osteocyte Newly calcified bone matrix Osteoid Osteoblast 1 Ossification centers appear in the fibrous connective tissue membrane. • Selected centrally located mesenchymal cells cluster and differentiate into osteoblasts, forming an ossification center that produces the first trabeculae of spongy bone. 2 Osteoid is secreted within the fibrous membrane and calcifies. • Osteoblasts begin to secrete osteoid, which calcifies in a few days. • Trapped osteoblasts become osteocytes. Mesenchyme condensing to form the periosteum Trabeculae of woven bone Blood vessel 3 Woven bone and periosteum form. • Accumulating osteoid is laid down between embryonic blood vessels in a manner that results in a network (instead of concentric lamellae) of trabeculae Called woven bone. • Vascularized mesenchyme condenses on the external face of the woven bone and becomes the periosteum. © 2013 Pearson Education, Inc. Fibrous periosteum Osteoblast Plate of compact bone Diploë (spongy bone) cavities contain red marrow 4 Lamellar bone replaces woven bone, just deep to the periosteum. Red marrow appears. • Trabeculae just deep to the periosteum thicken. Mature lamellar bone replaces them, forming compact bone plates. • Spongy bone (diploë), consisting of distinct trabeculae, persists internally and its vascular tissue becomes red marrow. Figure 6.9 Intramembranous ossification. (1 of 4) Mesenchymal cell Collagen fibril Ossification center Osteoid Osteoblast 1 Ossification centers appear in the fibrous connective tissue membrane. • Selected centrally located mesenchymal cells cluster and differentiate into osteoblasts, forming an ossification center that produces the first trabeculae of spongy bone. © 2013 Pearson Education, Inc. Figure 6.9 Intramembranous ossification. (2 of 4) Osteoblast Osteoid Osteocyte Newly calcified bone matrix 2 Osteoid is secreted within the fibrous membrane and calcifies. • Osteoblasts begin to secrete osteoid, which calcifies in a few days. • Trapped osteoblasts become osteocytes. © 2013 Pearson Education, Inc. Figure 6.9 Intramembranous ossification. (3 of 4) Mesenchyme condensing to form the periosteum Trabeculae of woven bone Blood vessel 3 Woven bone and periosteum form. • Accumulating osteoid is laid down between embryonic blood vessels in a manner that results in a network (instead of concentric lamellae) of trabeculae called woven bone. • Vascularized mesenchyme condenses on the external face of the woven bone and becomes the periosteum. © 2013 Pearson Education, Inc. Figure 6.9 Intramembranous ossification. (4 of 4) Fibrous periosteum Osteoblast Plate of compact bone Diploë (spongy bone) cavities contain red marrow 4 Lamellar bone replaces woven bone, just deep to the periosteum. Red marrow appears. • Trabeculae just deep to the periosteum thicken. Mature lamellar bone replaces them, forming compact bone plates. • Spongy bone (diploë), consisting of distinct trabeculae, persists internally and its vascular tissue becomes red marrow. © 2013 Pearson Education, Inc. Figure 6.10 Growth in length of a long bone occurs at the epiphyseal plate. Resting zone 1 Proliferation zone Cartilage cells undergo mitosis. 2 Hypertrophic zone Older cartilage cells enlarge. Calcified cartilage spicule Osteoblast depositing bone matrix Osseous tissue (bone) covering cartilage spicules © 2013 Pearson Education, Inc. 3 Calcification zone Matrix calcifies; cartilage cells die; matrix begins deteriorating; blood vessels invade cavity. 4 Ossification zone New bone forms. Figure 6.11 Long bone growth and remodeling during youth. Bone growth Cartilage grows here. Bone replaces cartilage here. Cartilage grows here. Bone replaces cartilage here. Bone remodeling Articular cartilage Epiphyseal plate Bone that was here has been resorbed. Appositional growth adds bone here. Bone that was here has been resorbed. © 2013 Pearson Education, Inc. Figure 6.12 Parathyroid hormone (PTH) control of blood calcium levels. Calcium homeostasis of blood: 9–11 mg/100 ml BALANCE BALANCE Stimulus Falling blood Ca2+ levels Thyroid gland Osteoclasts degrade bone matrix and release Ca2+ into blood. Parathyroid glands PTH © 2013 Pearson Education, Inc. Parathyroid glands release parathyroid hormone (PTH). Figure 6.13 Bone anatomy and bending stress. Load here (body weight) Head of femur Compression here Tension here Point of no stress © 2013 Pearson Education, Inc. Figure 6.14 Vigorous exercise can strengthen bone. Crosssectional dimension of the humerus Added bone matrix counteracts added stress Serving arm © 2013 Pearson Education, Inc. Nonserving arm Table 6.2 Common Types of Fractures (1 of 3) © 2013 Pearson Education, Inc. Table 6.2 Common Types of Fractures (2 of 3) © 2013 Pearson Education, Inc. Table 6.2 Common Types of Fractures (3 of 3) © 2013 Pearson Education, Inc. Figure 6.15 Stages in the healing of a bone fracture. Hematoma Internal callus (fibrous tissue and cartilage) 1 A hematoma forms. © 2013 Pearson Education, Inc. External callus Bony callus of spongy bone New blood vessels Healed fracture Spongy bone trabecula 2 Fibrocartilaginous callus forms. 3 Bony callus forms. 4 Bone remodeling occurs. Figure 6.15 Stages in the healing of a bone fracture. (1 of 4) Hematoma © 2013 Pearson Education, Inc. 1 A hematoma forms. Figure 6.15 Stages in the healing of a bone fracture. (2 of 4) External callus Internal callus (fibrous tissue and cartilage) New blood vessels Spongy bone trabecula 2 Fibrocartilaginous callus forms. © 2013 Pearson Education, Inc. Figure 6.15 Stages in the healing of a bone fracture. (3 of 4) Bony callus of spongy bone © 2013 Pearson Education, Inc. 3 Bony callus forms. Figure 6.15 Stages in the healing of a bone fracture. (4 of 4) Healed fracture © 2013 Pearson Education, Inc. 4 Bone remodeling occurs. Figure 6.16 The contrasting architecture of normal versus osteoporotic bone. Normal bone © 2013 Pearson Education, Inc. Osteoporotic bone Figure 6.16a The contrasting architecture of normal versus osteoporotic bone. Normal bone © 2013 Pearson Education, Inc. Figure 6.16b The contrasting architecture of normal versus osteoporotic bone. Osteoporotic bone © 2013 Pearson Education, Inc. Figure 6.17 Fetal primary ossification centers at 12 weeks. Parietal bone Frontal bone of skull Mandible Occipital bone Clavicle Scapula Radius Ulna Humerus Femur Tibia Ribs Vertebra Ilium © 2013 Pearson Education, Inc. System Connections 6.1 © 2013 Pearson Education, Inc.