C1/30/15 BONE I I. INTRODUCTIONA. Osteology: - the study of bones B. Bones are organs (two or more tissue types in each bone)C. Adult skeleton: 206 bones1. Skeleton subdivided into:a. Axial skeleton –bones of the head, neck and trunk b. Appendicular skeleton – bones of upper and lowerextremeties II. GROSS ANATOMY OF BONESA. Bone Shape1. Long Bonesa. longer than they are wide (fibula, tibia, philanges, femur, etc) 2. Short Bonesa. approx. as long as they are wide (carpel bones, tarsal bones, etc) 3. Flat Bonesa. relatively thin, have broad surface (sternum, etc)4. Irregular Bonesa. have irregular and varied shapes B. Gross Anatomy of a Long Bone1. Diaphysis - cylindrical shaft (ex:dumbbell—thin shaft diaphysis)2. Medullary Cavity - hollow inside of diaphysisa. lined with endosteum b. contains yellow bone marrow (adipose) 3. Epiphysis (plural: epiphyses) - ends of the bonea. outside layer of compact bone surrounding spongy boneb. in the spaces of the spongy bone =red bone marrow (hemopoietic tissue)-for blood cell production 4. Articular Cartilage - hyaline cartilage on the epiphysesa. helps joints move easily5. Epiphyseal Plate - hyaline cartilage plate between diaphysis and epiphysisa. Function: lengthwise bone growth 6. Periosteum - dense irregular connective tissue that covers outside of bonea. exception: periosteum not found on articular surfaces of boneb. Sharpey's fibers (perforating fibers)c. there are cells (osteoblasts) associate with the periosteum which are responsible for bone width growth III. BONE HISTOLOGYA. 3 kinds of cells:1. Osteoblasts: create bone2. Osteocytes: maintain bone matrix (osteoblast that surrounds itself with bone) 3. Osteoclasts: break down/reabsorb bone B. Compact bone: Made up of osteons = Haversian Systems 1. Osteons (Haversian Systems) consist of:a. Central Canal (Haversian Canal): opening that runs parallel to length of diaphysis; contains blood vessels/nervesb. Concentric Lamellae: rings of bone matrix around a central canal (3 concentric rings) 2. Lamellae: 3. Osteocytes: mature bone cells4. Lacunae: spaces where osteocytes reside5. Canaliculi: tiny channels that radiate from lacunae. Contain cytoplasmic projections of osteocytes for diffusion of nutrients 6. Perforating (Volkmann's) Canals: canals that run perpendicular to the central canals (long axis); connect central canals (have artery vein nerves in Volkmann canals)7. Interstitial Lamellae (Interstitial Systems): incomplete remnants of osteons 8. Circumferential Lamellae: rings of bone that run the entire circumference of the shaft; made by cells (osteoblasts) of periosteum. All of the following are part of a Haversian (osteon) system EXCEPT:a. Lamellaeb. Canaliculic. Haversian canald. Lacunaee.
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