MUSCULOSKELETAL SYSTEM PBM 218 Sunday, October 11, 15 PBM 218 WEBSITE http://users.bmap.ucla.edu/~amg/web/pbm_218.html Sunday, October 11, 15 BONE STRUCTURE & DEVELOPMENT Sunday, October 11, 15 MANY KINDS OF BONES • Living organ system • Blood supply • Many shapes • Long • Flat • Sutures Sunday, October 11, 15 BONE MORPHOLOGY • Epiphysis Cortical (hard) bone Trabecular Periosteum • Trabecular bone (spongy) bone (membrane covering bone) • Diaphysis • Cortical bone Articular cartilage • Periosteum • Medulla • Red medulla Blood Marrow vessels Epiphyseal plate • Yellow medulla Medullary cavity Sunday, October 11, 15 BONE MARROW • Red • Hematopoiesis • Red blood cells • White blood cells • Platelets • Yellow • Adipocytes Sunday, October 11, 15 BONE CELL TYPES • Osteoblasts • Bone forming cells • Osteocytes • Mature bone cells • Osteoclasts • Breakdown and resorb bone Sunday, October 11, 15 BONE STRUCTURE • Osteon • Osteonal canal • Haversian canal • Medullary canal • Blood vessels • Periosteal • Endosteal Sunday, October 11, 15 OSTEOGENESIS • 8 weeks after conception • Skeletal model formed from cartilage and connective tissue membranes • Endochrondrial ossification • Long bones • Intramembraneous ossification • Flat bones • Repair Sunday, October 11, 15 ENDOCHONDRAL OSSIFICATION • Begins in 3rd month after conception • Penetration of blood vessels into cartilage model of the bone • Osteoblasts form collar of hard bone around the diaphysis (lengthwise middle of bone) • Central cartilage disintegrates • Osteoblasts penetrate and form central spongy bone • Ossification continues from diaphysis to epiphysis (end of bone) Sunday, October 11, 15 ENDOCHONDRAL OSSIFICATION • Osteoclasts open the spongy bone to form the medullary cavity • Cartilage in the epiphysis continues to grow ahead of the ossification • Postnatal ossification centers around the epiphysis • Except interior remains spongy Sunday, October 11, 15 ENDOCHONDRAL OSSIFICATION • Cartilage at the ends remains and becomes articular cartilage • Cartilage remains between epiphysis and diaphysis (growth plate) • Growth region • Postnatal ossification occur here to allow growth (lengthening) • Completely hardens by early adult years Sunday, October 11, 15 EPIPHYSEAL PLATE • Epiphyseal plate (or line) • bone growth/elongation • fracture • infection Sunday, October 11, 15 ENDOCHONDRAL OSSIFICATION • In adult years bones can grow in diameter • Compact bone forms around the outer surface by osteoblast infiltration • Osteoclasts enlarge the medullary cavity Sunday, October 11, 15 BONES TO KNOW Calavera de Don Quixote by José Guadalupe Posada Sunday, October 11, 15 Sunday, October 11, 15.