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BONE ARCHITECTURE
Dnyanesh Lad
• Hardest structures• Toughness and elasticity Externally: Pink white Internally: Red• On section (1) Compact tissue-porous + dense like ivory (2) Cancellous tissue
MICROSCOPY SUBTYPE FEATURES EXAMPLE
LAMELLAR Cortical (80%)
Strong; slow turnoverAlong Lines Of Stress
Femoral shaft
Cancellous/ Spongy
>elastic; > turnover; < Young’s modulus
Distal femoral epiphysis
WOVEN Immature Non stress oriented
Embryonic skeleton# callus
Pathologic
Weak, Flexible,High turnover, Random
OsteosarcomaFibrous dysplasia
Periosteum
• Encloses bone
• Supplies blood vessels
• 2 layers (1)Outer-connective tissue+fat (2)Inner-elastic fibres forming a dense membranous network
• Medullary membrane/ Internal periosteum
Periosteum
In young • Thick• Vascular, • Loosely attached• Separated by soft
tissue with osteoblasts
• ossification on exterior of bone
In adults • Thin• Less vascular• Closely attached• Osteoblasts
converted to epitheloid layer.
• Carry lymph from bone
• RAMIFICATION OF VESSELS
• LIABILITY OF BONE EXFOLIATION OR NECROSIS.
BONE MARROW ADULT • yellow colour• Long bones• Composition: 96% fat 1% areolar tissue +
vessels 3 % fluida. fibrous tissueb. blood vesselsc. cells
CHILD1. Red colour2. Short flat bones3. Composition: 75% water 25% solid mattera. Cell globulinb. Nucleoproteidc. Extractivesd. Salte. Less fat
• TRUE “MARROW CELLS” OF KOLLIKER
red marrow Majority of the cells Roundish nucleated cells smallest-erythroblasts
• GIANT CELLS-MYELOPLAQUES- OSTEOCLASTS more in red marrow large multinucleated protoplasmic mass‘integrin’-attachTRAP + CA
Fn: absorbtion of bone matrix Evacuate pits/cavities-”HOWSHIPS LACUNAE”
VESSELS
• Compact bone- more numerous
• Cancellous bone-less numerous larger size. Come through compact tissue
• Largest and most numerous apertures for veins of cancellous tissue.
MEDULLARY / NUTRIENT ARTERY
High pressure system nutrient foramen; shaft accompanied by 1 or 2 veins branches in both directions to
medullary membrane anastamoses with br. Of compact
and cancellous tissue.
• METAPHYSEAL/EPIPHYEAL VESSELS From periarticular vascular plexus-
geniculate arteries
• PERIOSTEAL SYSTEM Low pressure system
• Arterial flow in mature bone is centrifugal d/t high pressure endosteal system
• In case of displaced fracture flow is reversed-becomes centripetal.
• Arterial flow in immature bone-centripetal since periosteum is highly vascularised.
VEINSEmerge from 3 places1. Accompany artery2. At the articular extremities.3. Arising in compact tissue
Venous flow in mature bone-centripetal
Cortical vessels-venous sinusoids-emissary venous system.
LYMPHATICS1. In periosteum2. Within bone in Haversian system
NERVES1. Freely distributed in periosteum2. Accompany nutrient vessels to interior3. Most numerous in –articular extremities vertebrae larger flat bones
MINUTE ANATOMY
Studied on transverse section Haversian systems1. Haversian canal 2. Lamallae 3. Lacunae4. Canaliculi
Haversian Canal / Volkmanns Canal• // to long axis of bone• Branch + communicate• Average diameter: 1/500th of an inch• Larger near medullary cavity• Contains- 2 blood vessels delicate connective tissue nerve filaments lymphatics
LAMELLAE
Primary / Fundamental / Circumferential-medullary cavity of bone would be the HC
Secondary / Special-Those laid down around actual HC
Interstitial -between the various circular systems, filling
the irregular intervals
LACUNAEbranched bone cell / corpuscleProcesses of cell pass through
canaliculiFn: fluids for nutrition brought in
contact with bone CANALICULI Do not communicate with the lacunae
of neighboring HS.
CHEMICAL STRUCTURE• Animal Part / Organic Part: 25% Bone Cells (4%) Matrix (20%)
• Earthy / Inorganic Part 65%
crystalline hydroxyappetite amorphous Ca2(PO4)3 Remainder: CaCO3, CaCl2 and MgSO4 Trapped ions: citrate, fluoride, Na K Mg
OSSIFICATION
• Intramembranous skull, maxilla, mandible, clavicle mesenchymal tissue-scaffold for ossifn
• Intracartilaginous
• Ring of Lacroix-epiphsial ring formed. Does not further extend to epiphysis
• Zone of Ranvier- ROL + lateral part of physis + mesenchymal cells
Ossification Centres
• Short bones: single point; in the centre
• Long bone: central point for diaphysis (1st) 1 or more for each extremity-epiphysis
• Union of epiphysis with shaft occurs in reverse order to that in which ossification began (exception : fibula)
• Regulated by direction of nutrient artery (knee-away ; elbow-towards)
• When 1 epiphysis; medullary artery is directed towards it.
• Eg: acromial end of clavicle distal end of the metacarpal bone of thumb and great toe proximal end of other metacarpals and metatarsals
THANK
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