Structure of bone
• Bone is a specialized form of
• It consists of :
1. Bone matrix
60% by weight
In the form of
25% by weight
90% Type I collagen.
Ground substance of
small amount of
proteins and lipids.
a) Ostoprogenator cells.
b) Osteoblasts .
c) Osteocytes .
d) Osteoclasts .
e) Bone lining cells.
• Bone forming cells
• Extensive endoplasmic reticulum
• Numerous mitochondria and vesicle
• Active in collagen and ground substance formation
• Produce intercellular substance called osteoid
• Large multinucleated cells
• Responsible for resorbtion of bone
• Found in depressions in the bone called
• An osteocyte, a star shaped cells is the most
commonly found cell in mature bone
• Osteocytes have an average half life of 25
years, they do not divide
• Occupy a space called lacuna
• Few organelles
• Play role in calcium homeostasis
• Mesenchymal fibroblast like cells
• Form stem cell population to generate
Bone lining cells
• Undifferentiated flattened cells
• Line the surface of bone when there is no
deposition or resorbtion
Periosteum and endosteum
• Layers of bone forming cells and connective
tissue cover the external and internal surface
• Provide nutrition to bone tissue
• supply new osteoblasts
Types of bone
1. Mature (Lamellar) bone:
Collagen fibers within each lamella are
Osteocytes are evenly distributed
a) compact bone
b) Spongy (Cancellous) bone
2. Immature (woven) bone
3. Bundle bone
• Denser than cancellous bone.
• Thick and solid
• Lamellae are organized in the form of concentric
cylinder surrounding a narrow canal
• 5-20 lamellae surround each canal
• The central vascular canal called Haversian
• Haversian canals are connected by transversely
running Volkmann’s canals
• Bony tissue characteristic
of the embryonic skeleton
in which the collagen
fibers of the matrix are
arranged irregularly in the
form of interlacing
• Less ground substance
and less calcified
• Healing sockets after teeth
• Collagen fibers of PDL
(Sharpey’s fibers) are
embedded in it
• More calcified
• Restricted to alveolar
The alveolar bone ( process )
• The part of maxilla or mandible which
supports and protect teeth.
• Dependent on the presence of teeth .
• Forms the bony socket to hold the root of tooth
and attach it through the PDL
• It gives attachment to muscle
• Framework for bone marrow
• Reservoir for calcium
Alveolar bone proper
• Forms the socket inner wall
• Gives attachment to periodontal ligament
• Perforated by many openings that carry
branches of interalveolar nerves and blood
vessels into PDL
• Consists of lamellated and bundle bone
Supporting alveolar bone
• Compact bone
• Thinner in the maxilla
• Thickest in molar and premolar region
lingual plate (inner plate)
labial plate (outer plate)
supporting spongy bone (Cancellous bone
between cortical plates and alveolar bone proper)
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