Bone Academia

8/3/2019 Bone Academia

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Bones are characterized anatomically as:

lon bones e. . humerus femur

flat bones (e.g. sternum and ribs )

. .

Dr Masharawi youssef1


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generally classified into two types:

ort ca compact

trabecular (cancellous, spongy)

of porosity and the unit microstructure.

Trabecular bone contributes about 20% of theo a s e e a mass w n e o y w ecortical bone contributes the remaining 80%.



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COMPACT, CORTICAL,

LAMELLAR BONE: Bone arranged in

concentric layerscalled lamellae ,with Haversian

Canals containingblood vessels in thecenter. Often found

around the outsideof large bones .



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A ears as a mass of bon tissue

lacking spaces visible to the unaided

eye Much denser with a porosity ranging

between 5% and 10%.

Found primary in the shaft of long bonesand forms the outer shell aroundcance ous one at t e en o o nts an

the vertebrae. The basic first level structure of corticalbone are osteons



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,

,B NE

Often found on inside, composed of

, of bone, around the bone-marrow

spaces .



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Trabecular cancellous, s on bone

The second type of bone.

Its basic first levels ruc ure s etrabeculae

=

irregular three-

dimensional arra ofboney rods and plates

Bone marrow fills the

Dr Masharawi youssef13 spaces of the pores


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.

makes up the majority of vertebral bodies

Trabecular bone is more com liant than

cortical bone and it is believed to distribute

contact loads.



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Trabecular (cancellous) bone

(cont.)

ra ecu ar one as a muc grea er

surface area than cortical bone

Trabecular bone is much more

porous w t poros ty rang nganywhere from 50% to 90%.

It is found in the end of long bones invertebrae and in flat bones like thepelvis.



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The substantial modulus reduction upon

that trabecular bone is a damaging material.



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A trabecular bone from

a human vertebral body

Note that the

volume fraction(ratio of bone to

very low.

Typical volume

fractions forvertebral bodies


and 20%.


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From fetal to 9 years old

ra ecu ar s ruc ure



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Stress on cortical bone


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