Essentials of Anatomy and Physiology Fifth edition Seeley, Stephens and Tate Skeletal System, Bones and Joints Slide 2.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Skeletal System Components of the skeletal system Bones (skeleton) Joints Cartilages Ligaments Slide 5.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Skeletal System Two subdivisions Axial skeleton Appendicular skeleton Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Appendicular skeleton Axial skeleton Skull Auditory ossicles and hyoid bone Vertebral column Thoracic cage Appendicular skeleton Pectoral and pelvic girdles Upper and lower limbs

Figure 7.1b

Functions of Bones Support of the body Protection of soft organs Movement due to attached skeletal muscles: “passive” Storage of minerals and fats Blood cell formation Slide 5.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Classification of Bones Long bones Typically longer than wide Have a shaft with heads at both ends Contain mostly compact bone Examples: Femur, humerus Slide 5.4a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Classification of Bones Short bones Generally cube-shape Contain mostly spongy bone Examples: Carpals, tarsals Slide 5.4b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Classification of Bones on the Basis of Shape Figure 5.1 Slide 5.4c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Classification of Bones Flat bones Thin and flattened Usually curved Thin layers of compact bone around a layer of spongy bone Examples: Skull, ribs, sternum Slide 5.5a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Classification of Bones Irregular bones Irregular shape Do not fit into other bone classification categories Example: Vertebrae and hip Slide 5.5b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Classification of Bones on the Basis of Shape Figure 5.1 Slide 5.5c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Structures of a Long Bone Articular cartilage Covers surface of epiphyses Hyaline cartilage Decreases friction at joint surfaces Figure 5.2a Slide 5.8a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Microscopic Anatomy of Bone Osteon (Haversian System) A subunit of compact bone Central (Haversian) canal Opening in the center of an osteon Carries blood vessels and nerves Slide 5.10a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Microscopic Anatomy of Bone Figure 5.3 Slide 5.10b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Microscopic Anatomy of Bone Lacuna(e) Cavities containing osteocytes Arranged in concentric rings Lamella(e) Rings of compact bone Lacunae lie between rings Figure 5.3 Slide 5.11a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Microscopic Anatomy of Bone Canaliculi (-us) Tiny canals Radiate from the central canal to lacunae Form a transport system Figure 5.3 Slide 5.11b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Types of Bone Cells Osteocytes Osteoblasts Osteoclasts Mature bone cells (bone maintenance) Osteoblasts Bone-forming cells Osteoclasts Bone-destroying cells Break down bone matrix for remodeling and release of calcium Slide 5.15 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Long Bone Formation and Growth Figure 5.4a Slide 5.14a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Long Bone Formation and Growth Figure 5.4a Slide 5.14a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Long Bone Formation and Growth Figure 5.4a Slide 5.14a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Long Bone Formation and Growth Figure 5.4b Slide 5.14b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Long Bone Formation and Growth Figure 5.4a Slide 5.14a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Bone Growth: Intramembranous “Between membranes” Compact Bone Spongy Bone Trabeculae Cross-section of a trabecula Slide 5.12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Common Types of Fractures Table 5.2 Slide 5.17 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Repair of Bone Fractures Fracture Repair Hematoma formation (A) Callus formation (B) Bone replacement (C ) Bone remodeling (D) A B C D Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings