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Osseous Tissue• Categories of bone
• Functions of bone
• Histology of osseous tissue
• Bone development (osteogenesis)
• Select Bone disorders
General Bone Classifications
Examples
Long bones (i.e.)
Short bones
Flat bones
Sesamoid bones
Irregular bones
Wormian bones
Figure 6.3a-b
Proximalepiphysi
s
(b)
Epiphyseal
line
Articulacartilag
e
Periosteum
Spongy bone
Compact boneMedullary
cavity (linedby
endosteum)
Compact bone
Diaphysis
Distalepiphysi
s
Diaphysis
Epiphysis
Metaphysis
Epiphyseal Growth Plate (line)
Structure of a Flat Bone• External and internal surfaces of
flat bone are composed of compact bone
• Middle layer is spongy bone (diploe).
Copyright © 2010 Pearson Education, Inc. Figure 6.4a-b
(a) Osteogenic cell (b) Osteoblast
Stem cellcell responsiblefor bone growth
Bone Anatomy Outside Periosteum 2 layered membrane
1. Outer fibrous layer (Sharpey’s Fibers~see image)
2. Inner osteogenic layer contains osteoblasts, osteoclasts, and osteogenic cellsInside Medullary Cavity (inside?)
EndosteumContains osteoblasts, osteoclasts, and osteoprogenitor or osteogenic cells
Bone Histology
2 types of Bone (Compact and Spongy) 1. Compact Bone
consists of organized lamellae (layers or plates) 3 arrangements---and associated descriptive term
1. Concentric lamellae2. Interstitial lamellae3. Circumferential lamellae (All with collagen inside)
Canals central canals perforating canals canaliculi
Figure 6.7a-c
Perforating (Volkmann’s) canal
Perforating (Sharpey’s) fibersPeriosteal blood
vesselPeriosteum
Lacuna (withosteocyte)
(a)
(b)
(c)
Lacunae
Lamellae
NerveVein
ArteryCanaliculi
Osteocytein a lacuna
Circumferentiallamellae
Osteon(Haversian
system)
Central(Haversian)
canal
Central
canalInterstitial lamellae
Lamellae
Compact
bone
Spongy bone
Figure 6.6
Structures
in thecentralcanal
Artery with
capillariesVeinNerve
fiber
Lamellae
Collagenfibersrun in
differentdirection
s
Twistingforce
Bone Histology
2. Cancellous or Spongy Lamellae
Trabeculae---no Osteons!
These are oriented along lines of stress and provide structural strength to the bone.
Fig. 6.4
Ossification or Osteogenesis (bone formation)
1. Intramembranous ( skull bones and mandible)
Osteoblasts differentiate directly from mesenchyme (embryonic tissue) and secrete osteoid
2. Endochondral (most other bones) Ossification takes place within a piece of hyaline cartilage, the shape resembling the bone.
Bone RemodelingWolff’s law: A bone grows or remodels in response to forces or demands placed
upon it.Observations supporting Wolff’s law:
Handedness Larger bony projections
Hormonal influences of calcium and bone deposition/resorption/plate closure
Calcitonin (from, target, action)
PTH (from, target, action)
Estrogen and Testosterone
Injury to plate?
GREENSTICK FRACTURE
Mettler: Essentials of Radiology, 2nd ed., Copyright © 2005 Saunders, An Imprint of Elsevier