Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Human Anatomy & Physiology, Sixth Edition Elaine N. Marieb PowerPoint ® Lecture Slides prepared by Vince Austin, University of Kentucky 6 Bones and Skeletal Tissues

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Functions of Skeletal System A. Support B. Protection C. Movement D. Mineral Storage (Calcium + Phosphorus) E. Hematopoiesis (blood cell formation in red marrow) F. Energy Storage (lipids/fat stored in yellow marrow)

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Hyaline Cartilage  Provides support, flexibility, and resilience  Is the most abundant skeletal cartilage  Is present in these cartilages: Articular – covers the ends of long bones Costal – connects the ribs to the sternum Respiratory – makes up the larynx and reinforces air passages Nasal – supports the nose

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Hyaline Cartilage

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Elastic Cartilage  Similar to hyaline cartilage but contains elastic fibers  Found in the external ear and the epiglottis

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Elastic Cartilage

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Fibrocartilage  Highly compressed with great tensile strength  Contains collagen fibers  Found in intervertebral discs

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Fibrocartilage

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Bones and Cartilages of the Human Body Figure 6.1

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Histology of Skeletal Tissue (Osseous Tissue) A. Different Cell Types 1. osteoprogenitor cells give rise to osteoblasts a. found in periosteum, endosteum, and canals 2. osteoblasts secrete proteins, Ca, P a. found on bone surface (where growth occurs) 3. osteocytes maintain bone integrity a. in the bone tissue itself, matrix surrounds 4. osteoclasts degrade and absorb bone during growth a. derived from white blood cells, on surface

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings B. Chemical Composition 1. 33% collagenous fibers as in connective tissue 2. 67% mineral salts - calcium phosphate + carbonate 3. hardening depends on correct amount of each

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings General Anatomy of a Long Bone (eg. humerus) A. Diaphysis - main shaft of the bone B. Epiphysis - large end of the bone C. Metaphysis - where above meet during bone growth D. Articular Cartilage - covers epiphysis, reduce friction E. Periosteum - dense, white covering around the bone a. fibrous layer - blood, lymph, nerves pass through b. osteogenic layer - where bone cells originate F. Medullary (marrow) Cavity - adults, yellow marrow G. Endosteum - lines medullary cavity, houses bone cells

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 6.3

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Classification of Bones  Axial skeleton – bones of the skull, vertebral column, and rib cage  Appendicular skeleton – bones of the upper and lower limbs, shoulder, and hip

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Classification of Bones: By Shape  Long bones – longer than they are wide (e.g., humerus) Figure 6.2a

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Classification of Bones: By Shape Figure 6.2b  Short bones  Cube-shaped bones of the wrist and ankle  Bones that form within tendons (e.g., patella)

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Classification of Bones: By Shape  Flat bones – thin, flattened, and a bit curved (e.g., sternum, and most skull bones) Figure 6.2c

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Classification of Bones: By Shape  Irregular bones – bones with complicated shapes (e.g., vertebrae and hip bones) Figure 6.2d

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Depressions and Openings fissure - cleft-like opening between adjacent parts of bones through which vessels & nerves pass foramen - hole through which blood vessels, nerves, ligaments can pass meatus - tunnel-like passageway through a bone sinus - cavity within a bone with narrow opening sulcus - groove or depression that accommodates a soft structure such as vessels, nerve, tendon fossa - depression in/on a bone; generally at a joint process - prominent projection or point of attachment

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Articular Processes (of the joints) condyle - large, rounded articular (joint) prominence head - rounded articular projection supported by a more constricted portion of a bone (neck) facet - smooth, flat surface on a bone

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Processes for Attachment tubercle - small, rounded process tuberosity - large, rounded, usually rough process trochanter - large, blunt projection; only on the femur line - less prominent ridge than a crest spine - sharp, slender process epicondyle - prominence found "above" a condyle

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Gross Anatomy of Bones: Bone Textures  Compact bone – dense outer layer  Spongy bone – honeycomb of trabeculae filled with yellow or red bone marrow

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Structure of Long Bone Long bones consist of a diaphysis (shaft) and an epiphysis (head) Diaphysis(es)  Tubular shaft that forms the axis of long bones  Composed of compact bone that surrounds the medullary cavity  Yellow bone marrow (fat) is contained in the medullary cavity

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Structure of Long Bone Epiphysis(es)  Expanded ends of long bones  Exterior is compact bone, and the interior is spongy bone  Joint surface is covered with articular (hyaline) cartilage  Epiphyseal line separates the diaphysis from the epiphyses

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Bone Membranes Periosteum – double-layered protective membrane  Outer fibrous layer is dense regular connective tissue  Inner osteogenic layer is composed of osteoblasts and osteoclasts  Richly supplied with nerve fibers, blood, and lymphatic vessels, which enter the bone via nutrient foramina  Secured to underlying bone by Sharpey’s fibers Endosteum – delicate membrane covering internal surfaces of bone

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Microscopic Structure of Bone: Compact Bone Haversian system, or “osteon” – the structural unit of compact bone  Lamella – weight-bearing, column-like matrix tubes composed mainly of collagen  Haversian or “central” canal – central channel containing blood vessels and nerves  Volkmann’s canals – channels lying at right angles to the central canal, connecting blood and nerve supply of the periosteum to that of the Haversian canal  Osteocytes – mature bone cells  Lacunae – small cavities in bone that contain osteocytes  Canaliculi – hair-like canals that connect lacunae to each other and the central canal

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Figure 6.6a, b

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Chemical Composition of Bone: Inorganic Hydroxyapatites, or mineral salts  Sixty-five percent of bone by mass  Mainly calcium phosphates  Responsible for bone hardness and its resistance to compression

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Bone Development Osteogenesis and ossification – the process of bone tissue formation, which leads to:  The formation of the bony skeleton in embryos  Bone growth until early adulthood  Bone thickness, remodeling, and repair

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Formation of the Bony Skeleton  Begins at week 8 of embryo development (1) Intramembranous ossification – bone develops from a fibrous membrane (2) Endochondral ossification – bone forms by replacing hyaline cartilage

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings (1) Intramembranous Ossification  Formation of most of the flat bones of the skull and the clavicles  Fibrous connective tissue membranes are formed by mesenchymal cells

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Stages of Intramembranous Ossification  An ossification center appears in the fibrous connective tissue membrane  Bone matrix is secreted within the fibrous membrane  Woven bone and periosteum form  Bone collar of compact bone forms, and red marrow appears  5 stages for intramembranous ossification

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 6.7.1

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 6.7.2

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 6.7.3

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 6.7.4

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings (2) Endochondral Ossification  Begins in the second month of development  Uses hyaline cartilage “bones” as models for bone construction  Requires breakdown of hyaline cartilage prior to ossification

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Stages of Endochondral Ossification  Formation of bone collar  Invasion of internal cavities by the periosteal bud, and spongy bone formation  Formation of the medullary cavity; appearance of secondary ossification centers in the epiphyses  Ossification of the epiphyses, with hyaline cartilage remaining only in the epiphyseal plates

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Formation of bone collar around hyaline cartilage model Cavitation of the hyaline cartilage within the cartilage model. Invasion of internal cavities by the periosteal bud and spongy bone formation. 5 Ossification of the epiphyses; when completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilages Formation of the medullary cavity as ossification continues; appearance of secondary ossification centers in the epiphyses in preparation for stage 5. Hyaline cartilage Primary ossification center Bone collar Deteriorating cartilage matrix Spongy bone formation Blood vessel of periostea l bud Secondary ossification center Epiphyseal blood vessel Medullary cavity Epiphyseal plate cartilage Spongy bone Articular cartilage Stages of Endochondral Ossification Figure 6.8

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Functional Zones in Long Bone Growth  Growth zone – cartilage cells undergo mitosis, pushing the epiphysis away from the diaphysis  Transformation zone – older cells enlarge, the matrix becomes calcified, cartilage cells die, and the matrix begins to deteriorate  Osteogenic zone – new bone formation occurs

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Long Bone Growth and Remodeling  Growth in length – cartilage continually grows and is replaced by bone as shown  Remodeling – bone is resorbed and added by appositional growth as shown

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 6.10

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Osteoblasts beneath the periosteum secrete bone matrix, forming ridges that follow the course of periosteal blood vessels As the bony ridges enlarge and meet, the groove containing the blood vessel becomes a tunnel. The periosteum lining the tunnel is transformed into an endosteum and the osteoblasts just deep to the tunnel endosteum secrete bone matrix, narrowing the canal. As the osteoblasts beneath the endosteum form new lamellae, a new osteon is created. Meanwhile new circumferential lamellae are elaborated beneath the periosteum and the process is repeated, continuing to enlarge bone diameter. Artery Periosteum Penetrating canal Central canal of osteon Periosteal ridge Appositional Growth of Bone Figure 6.11

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Bone Deposition a. Ca and P in proper amount in diet b. trace amounts of Boron and Manganese c. Vitamin D - regulates Ca metabolism d. Vitamin C - maintenance of bone matrix e. Vitamin A - osteoclast/blast function f. Vitamin B12 - osteoblast function g. Human Growth Hormone (HGH) - pituitary h. Calcitonin - thyroid, Ca absorption to bone i. Parathormone - parathyroid, Ca release to blood j. Sex Hormones - Testosterone + Estrogen

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Bone Resorption  Accomplished by osteoclasts  Resorption bays – grooves formed by osteoclasts as they break down bone matrix  Resorption mostly involves osteoclast secretion of: --- Lysosomal enzymes that digest organic matrix

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Chemical Composition of Bone: Organic  Osteoblasts – bone-forming cells  Osteocytes – mature bone cells  Osteoclasts – large cells that resorb or break down bone matrix