1.bone and cartilage-final
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Good morning….
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Bone And Cartilage
By Navya P.
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BONE
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In the evolutionary ladder bone is just young to cartilage
!uite young com"ared to a nerve and much younger than acell. Bone evolved just about #$$ millions years ago
in this %&$$ million years old earth
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'hen li(e began All li(eresided in the ocean .
Almost every creature"resent then )ould be)earing some sort o( an
e*ternal armor.
But this armor or
e*os+eleton)as o( either a mi*ture o("rotein , chitin or o( calciumcarbonate e*tracted (romsea )ater.
Ref: SCIENTIFIC AMERICAN; Understanding Origins: SEP 2009:Pg 75 5
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-rue bone
It all started )ith (ishes.
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• -hus the /st evidence o( e*ternal bone )as about #%$
million years ago
• -he (irst to develo" internal bones then (ollo)ed.
• Eventhough evolved later bone no) is one o( the mostim"ortant o( its (unctions.
• -o us )ho are in the orthodontic (ield it matters evenmore.
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• Bone is a living tissue )hich ma+es u" the body
s+eleton and is one o( the hardest structure o( the
animal body.
• In an adult the s+eleton com"rises around /%0 o( the
total body )eight.
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• -he biggest bone in the body is the (emur and the
smallest is the sta"es bone in the middle ear.
• An adult human has around 1$& bones.
• -hese bones are organi2ed into a longitudinal a*is thea*ial s+eleton to )hich the a""endicular s+eleton is
attached
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AIA! S"E!ETON
It consists o( the 3$bones in the head andtrun+ o( the human body#
APPEN$ICU!AR S"E!ETON
Is com"osed o( /1& bones in the human body.
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FUNCTIONS OF S"E!ETON SUPPORT
• 4ha"e
• Protection
• Assisting In 5ovement
• 4torage O( 5inerals
• Production O( Blood Cells
• 5aintenance O( Acid6base Balance
• 7eto*i(ication
•
-ransduction O( 4ound 11
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C8A44I9ICA-ION O9 BONE
BA4E7 ON -:EI; 4:APE8ong bones4hort bone9lat bone
Irregular bone4esamoid bone<Bones that develo" in s"eci(ictendons
BA4E7 ON -E=->;E O9 C;O44 4EC-ION
CorticalCancellous
12;e(? Orban@s Oral :istolo , Embr olo Edited b G.4.umar 5osb Elsevier /1th edt
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BA4E7 ON 5A-;I= A;;ANGE5EN- 8amellar
'ovenCom"actBundle
BA4E7 ON 5A->;I-Immature bone5ature bone
BA4E7 ON 7EDE8OP5EN-A8 O;IGIN
Intramembraneous boneIntracartilagenous bone
13;e(? Orban@s Oral :istology , Embryology Edited by G.4.umar 5osby Elsevier /1th edt
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Long bones
Short bones 14
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%ROSS STRUCTURE OF !ON% &ONE
-he gross structure o( a long bone can be divided intoseveral regions.
E"i"hysis? In the long bones the e"i"hysis is the regionbet)een the gro)th "late and the e*"anded end o( bonecovered by articular cartilage.
An e"i"hysis consists o( abundant trabecular bone and athin shell o( cortical bone.
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•
E"i"hysis is "resent at eachend o( the long limb bones.
• It is (ound at only one endo( the 5etacar"als
metatarsals "halangesclavicles and ribs.
• -he e"i"hysis is the location
o( secondary ossi(icationcenters during develo"ment.
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5eta"hysis? -he junctional region bet)een the gro)th "lateand the dia"hysis.
-he meta"hysis contains abundant trabecular bone but thecortical bone thins here relative to the dia"hysis.
-his region is a common site (or many "rimary bone tumorsand similar lesions.
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7ia"hysis? -he dia"hysis is the sha(t o( long bones andis located in the region bet)een meta"hyses com"osed
mainly o( com"act cortical bone.
-he medullary canal contains marro) and a small amounto( trabecular bone.
Physis e"i"hyseal "late gro)th "lateF? -he "hysis is theregion that se"arates the e"i"hysis (rom themeta"hysis.
It is the 2one o( endochondral ossi(ication in an activelygro)ing bone or the e"i"hyseal scar
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9lat bone
• F'at ()nes are bones )hose "rinci"al (unction iseither e*tensive "rotection or the "rovision o(broad sur(aces (or muscular attachment.
• -hese bones are e*"anded into broad (lat "latesas in the cranium.
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-hese bones are com"osed o( t)o thin layerso( com"act bone enclosing bet)een them a variable!uantity o( cancellous bone )hich is the location o(red bone marro)
In an adult most red blood cells are (ormed in (latbones.
9lat bones in human s+ull
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9lat bones
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Irregular bones
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Irregular bones
• -he irregular bones are bones )hich (rom their"eculiar (orm cannot be grou"ed as long bone shortbone (lat bone or sesamoid bone
• Irregular bones serve various "ur"oses in the bodysuch as "rotection o( nervous tissue a((ordingmulti"le anchor "oints (or s+eletal attachment
maintaining "haryn* and trachea su""ortand tongue attachment.
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• -hey consist o( cancellous tissue enclosed )ithina thin layer o( com"act bone.
•
Irregular bones can also be used (or joining all"arts o( the s"inal column together.
Irregular bones in human s+ull.
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Cortical BoneHCom"act Bone H7ense Bone
• It is one o( t)o main ty"es o( osseous tissue.
• Cortical bone is dense and (orms the sur(ace o(bones.
• It is solid in a""earance and constitutes 3$0 o( totalbone mass.
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• Com"act bone is com"osed o( many cylinder sha"edunits called osteons or :aversian 4ystems and
transverse channels bet)een them called Dol+mannsCanal.
• -here are cavities inside com"act bones )here bone
marro) is stored.
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Cancellous Bone H4"ongy Bone H-rabecular
Bone • It is one o( t)o ty"es o( osseous tissue that
(orm bones. • Com"ared to com"act bone it has a higher
sur(ace area but is less dense so(ter )ea+erand less sti((.
• It ty"ically occurs at the ends o( long bones"ro*imal to joints and )ithin the interior o(vertebrae.
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• Cancellous bone is highly vascular and (re!uentlycontains red bone marro) )here hemato"oiesis the"roduction o( blood cells occurs.
• -he "rimary anatomical and (unctional unit o(cancellous bone is the trabecula.
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8amellar Bone
• 5ature bone.
• 4trong highly organi2ed )ell minerali2ed tissue.
•
5a+es u" more than JJ0 o( the adult humans+eleton.
• 9ull strength o( lamellar bone that su""orts anorthodontically moved tooth is not achieved untila""ro*imately / year a(ter com"letion o( activetreatment.
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'oven Bone
•
It is ne)ly (ormed bone later re"laced by lamellarbone. In contrast to mature bone it does not have alamellar structure.
•
Bundles o( collagen (ibers run randomly in di((erentdirections interlacing )ith each other.:ence name)oven )eave (abric interlacing threadsF.
•
;elatively )ea+ disorgani2ed and "oorly minerali2ed.
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• Crucial role in )ound healing by
• ;a"idly (illing osseous de(ects.
• Provides initial continuity (or (ractures and
osteotomy segments.
• 4trengthening a bone )ea+ened by surgery or
trauma.
Ne)ly or (irst (ormed bone in res"onse to
orthodontic load.
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Com"osite Bone
• Osseous tissue (ormed by the de"osition o( lamellar
bone )ithin a )oven bone lattice a "rocess calledcancellous com"action.
•
Kuic+est means o( "roducing relatively strong bone.
• An im"ortant intermediary ty"e o( bone in "hysiologicres"onse to orthodontic loading.
• It usually is the "redominant osseous tissue (orstabili2ation during early "rocess o( retention.
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• Although the com"osite bone may be o( high !uality load
bearing osseous tissue is eventually remodeled into
secondary osteon.
;e(? -. 5 . Graber ;.8. Danarsdall orthodontics current "rinci"les and techni!ues Lrd edition
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Bundle bone
• It is a (unctional ada"tation o( lamellar structure toallo) attatchment o( tendons and ligaments.
•
Per"endicular striations called 4har"ey (ibers are themajor distinguishing characteristics o( bundle bone.
• Bundle bone is the mechanism o( ligament and tendonattachment throughout the body
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Immature Bone Primary Bone -issueF
Immature bone is )oven bone.
5ature bone secondary bone tissueF
5ature bone is characteristically lamellar bone.
Almost all bones in adults are lamellar bones.
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Intramembranous Bone 5esenchymal BoneF
Intramembranous bone develo"s (rom directtrans(ormation o( condensed mesenchyme.
9lat bones are (ormed in this )ay.
Intracartilaginous Bone Cartilage Bone EndochondralBoneF
Intracartilaginous bone (orms by re"lacing a
"re(ormed cartilage model.
8ong bones are (ormed in this )ay
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:istology o( bone
• -he osteon is the (undamental (unctional unit o(com"act bone.
• Each osteon consists o( concentric layers or lamellaeo( com"act bone tissue that surround a central canal
the haversian canal.
• -he haversian canal contains the bones nerve andblood su""lies.
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• -he boundary o( an osteon is the cement line.
• 4ome o( the osteoblasts develo" into osteocytes each
living )ithin its o)n small s"ace or lacuna.
• Osteocytes ma+e contact )ith cyto"lasmic "rocesseso( their counter"arts via a net)or+ o( small transverse
canals or canaliculi. -his net)or+ (acilitates thee*change o( nutrients and metabolic )aste.
• Collagen (ibers in a "articular lamella run "arallel toeach other
• Osteons are connected to each other andthe "eriosteum by obli!ue channels called Dol+mannscanals.
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Parts O( Bone
Periosteum
Periosteum is the highly vascular membranous tissuecovering the bone that brings blood and lym"h vessels
as )ell as nerves to it .
9unctions o( "eriosteum
Bone nutrition8ongitudinal and transverse gro)th o( bone;egeneration
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Periosteum has t)o layers
M E*ternal<(ibrous made o( dense irregular
connective tissue.
M Internal<cellular contains many osteoblasts andblood vessels some osteocytes as )ell.
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Endosteum
• It is a lining covering a bone (rom the marro) side
made o( loose irregular connective tissue )ithosteoblasts and osteoclasts in addition to morecommon cell ty"es o( this tissue.
•
It is a highly vascular condensation o( areolar tissuelining the various medullary s"aces
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Com"act bone
• Consists o( dense de"osits o( minerals<chie(ly calcium"hos"hate and -y"e I collagen.
• -hese are arranged in concentric circles around acentral :aversian canal through )hich blood lym"h
vessels as )ell as nerves "ass through.
4"ongy bone
• -he mineral de"osits are arranged as a system o(struts.
• Bone marro) (ills the s"aces bet)een.
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Bone marro)• 4ome bones such as the (emur also contain a central
cavity (illed )ith bone marro).
• Bone marro) contains the stem cells that give rise to allthe ty"es o( blood cells.
E"i"hyseal "late
• >ntil the end o( "uberty this dis+ o( cartilage "roducesmore cartilage )hich then is converted into bone.
• In this )ay the bone gro)s length)ise.
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4chematic re"resentation o( structure o( a ty"ical long bone
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Com"osition O( Bone
Cellular com"onents/$0F
OsteoblastOsteoclast
Osteocytes8ining cellsosteo"rogenitors
E*tracellular com"onentsJ$0F
OrganicL#0FGround substance
Collagen (ibers
Inorganic�FCalciumPhos"horous
4odiummagnesium
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Osteo"rogenitors
•
-hese are stem cells o( mesenchymal origin , they canconvert into osteoblast )hen ever there is a need.
• ;esemble young (ibroblasts.
• -hey are more in (etus at the site )here bone
(ormation is to ta+e "lace.
•
In adult they are "resent over both "eriosteal ,endosteal sur(aces.
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• Also "resent in "erichondrium
• -)o ty"es
• Committed osteo"rogenitor 6 di((erentiate into
"reosteoblasts6osteoblasts
• Inducible osteo"rogenitor may di((erentiate
into (ibroblasts myoblasts adi"ose cellschondroblasts etc
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Osteoblast
•
7erived (rom osteo"rogenitor cells o( mesenchymalorigin )hich are "resent in bone marro)
• Periosteum serves as the im"ortant reservoir o(osteoblasts es"ecially in gro)ing children.
• Are baso"hilic varied in sha"es oval triangularCuboidalF.
•
-hey are res"onsible (or synthesis de"osition andminerali2ation o( bone matri*
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Osteoclasts
• Osteoclasts arise by (usion o( monocytes derived (rom
bone marro).
• -y"e o( bone cell that removes bone tissue.
• 8arge cell %6/$$ m in diameter.
• Numerous nuclei ? u" to 1$ or more.
• Dariable in sha"e due to their motility.
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Osteocyte
• -he osteocyte is estimated to ma+e u" more than J$0o( the bone cells in an adult s+eleton.
• -hey "lay an essential role in maintenance o( bone.
• 5ore in young decreasing )ith age.
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B 8i i C ll
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Bone 8ining Cells
• Bone lining cells are thin elongated cells that cover most
bone sur(acesE,PF in the mature s+eleton .
• Cyto"lasmic e*tensions or ga" junctions o(ten lin+ them
to each
other or to osteocytes.
• 5etabolically inactive cells.
• ;esting osteoblastsQ or Qsur(ace osteocytes.
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• In the "resence o( "arathyroid hormone these cells
secrete en2ymes that remove the osteoid covering o( the
bone matri* in "re"aration (or osteoclastic removal o(
bone.
• Bone lining cells may be "recursors (or osteoblasts
regulate the crystal gro)th in bone or (unction as a
barrier bet)een e*tracellular (luid and bone.
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Organic constituents
CO88AGEN
• -y"e I collagen (ibers about J#0F
•
-y"e D R#0• -he elasticity o( these im"arts ;E4I8IENC to the
tissue and hel"s to resist (racture.
.
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I i C tit t
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Inorganic Constituents
• Consists mainly hydro*ya"atite crystals )ith
carbonate content .
• :ydro*ya"atite crystals are thin "late or lea( li+estructure "ac+ed "arallel to collagen (ibrils.
• Ga"s bet)een crystals contains )ater and organicmolecules .
• 4mall amount o( calcium "hos"hate magnesium(luoride sodium "otassium (luoride iron 2inc etc.
• -hese minerals give bone its characteristic hardness and
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• -hese minerals give bone its characteristic hardness and
the ability to resist com"ression.
• Bone has to be #$0 minerali2ed to be seen in
radiogra"hs.
• Pea+ bone mass is reached bet)een ages 1$6L$ A(ter
this age bone loss begins.
• 3$0 o( the (actors that determine "ea+ bone mass are
genetic.
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BONE 7EDE8OP5EN-
BONE 9O;5A-ION H O4-EOGENE4I4 H O44I9ICA-ION
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BONE 9O;5A-ION H O4-EOGENE4I4 H O44I9ICA-ION
Bone (ormation occurs by three co6ordinated "rocesses?-he "roduction o( osteoid matri*-he maturation o( osteoid matri*5inerali2ation o( the matri*.
In the embryo bone tissue arises through t)o "rocesses
Intramembraneous Endochondral
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• In both ossi(ication "rocesses "re6e*isting connectivetissue is re"laced by bone.
• In intramembranous ossi(ication 6 some mesenchyme cellsare trans(ormed into osteoblasts and start laying do)nbone.
•-his is an ossi(ication "rocess that trans(orms membraneinto bone.
• Intramembraneous ossi(ication is seen in areas li+eCranial vault5a*illa5andible e*ce"t condylar cartilage
• Occurs in areas e*"osed to tension.
• In endochondral ossi(ication 6 a hyaline cartilage model o(
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In endochondral ossi(ication 6 a hyaline cartilage model o(the bone is ossi(ied.
•
Endochondral ossi(ication is the "rocess associated )ith(oetal bone develo"ment day6to6day bone gro)th and to acertain e*tent 6 (racture re"air.
• -his is the ty"e o( bone (ormation (ound in
8ong bones such as the (emur and humerus4ynchondroses o( cranial baseCondylar cartilageNasal se"tal cartilage.
• Occurs in regions e*"osed to high level o( com"ression.
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• -hese t)o +inds o( ossi(ication do not lead to di((erencesin the structure o( mature bones.
• -hey sim"ly indicate di((erent methods a bone (ormation.
• Both mechanisms involve the re"lacement o( a "ree*istingconnective tissue )ith bone.
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• -he (irst stage in the develo"ment o( bone is themigration o( mesenchymal cellsembryonic connective
tissue cellsF into the area )here bone (ormation isabout to begin.
• -hese cells increase in number and si2e.
• In some s+eletal structures )here ca"illaries arelac+ing they become chondroblasts.
• -he C:ON7;OB8A4-4 )ill be res"onsible (orcartilage (ormation.
4-EP4 O9 IN-;A5E5B;ANO>4 O44I9ICA-ION
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4-EP4 O9 IN-;A5E5B;ANO>4 O44I9ICA-ION
/. 4elected mesenchymal cellscluster and (orm osteoblasts.
1. -his (orms an ossi(icationcenter.
L. Osteoblasts begin to secrete
osteoid )hich minerali2ed.%. -he osteoblasts are tra""ed
di((erentiate into osteocytes.
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#. Accumulating osteoid islaid do)n bet)een
embryonic blood vessels.&. -his (orms a net)or+ o(trabulae.
S. Dasculari2ed mesenchymecondenses on the e*ternal
sur(ace o( the )ovenbone and becomes the"eriosteum.
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3. -rabeculae just dee" tothe "eriosteum thic+en(orming a bone collar.
J. -he bony collar is laterre"laced )ith maturecom"act bone.
/$. 4"ongy bone consistingo( distinct trabeculaeare "resent internally.Blood vesselsdi((erentiate into redbone marro).
4-EP4 O9 EN7OC:ON7;A8 O44I9ICA-ION
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• Early in embryonic li(e a cartilage model or tem"late o(the (uture bone is laid do)n. -his model is covered by amembrane called the PE;IC:ON7;I>5.
• 5id)ay along the sha(t o( this model a blood vessel"enetrates the "erichondrium stimulating cells in the
internal layer o( the "erichondrium to enlarge andbecome osteoblasts.
• -he osteoblasts begin to (orm a collar o( com"act bone
around the middle o( the dia"hysis o( the cartilagemodel.
• Once the "erichondrium starts to (orm bone it is calledthe PE;IO4-E>5.
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/. -he "erichondriumcovering the hyalinecartilage model o(boneTis in(iltrated )ith bloodvessels.
1. Osteoblasts secreteosteoid against thehyaline cartilage
dia"hysis encasing it ina bony collar.
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L. Chondrocytes )ithin thedia"hysis hy"ertro"hyand signal thesurrounding cartilagematri* to calci(y.
%. -he chondrocytesho)ever die and the
matri* begins todeteriorate.
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#. In month L the
(orming cavities areinvaded by a collectiono( elements called the"eriosteal bud.
&. -he enteringosteoclasts "artiallyerode the calci(ied
cartilage matri*.
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S. Osteoblasts secreteosteoid around the
remaining (ragmentso( hyaline cartilage(orming trabeculae.
3. As the "rimaryossi(ication centerenlarges osteoclastsbrea+ do)n the ne)ly(ormed s"ongy bone
and o"en u" amedullary cavity in thecenter o( thedia"hysis.
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J. -he e"i"hyses remain(ormed o( cartilage until
shortly be(ore or a(terbirth.
/$. 4econdary ossi(icationcenters (orm in the
e"i"hyses. -he eventso( ossi(ication are li+ethe events o( thedia"hysis e*ce"t thats"ongy bone mains in theinternal and nomedullary cavity (orms.
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5inerali2ation
•
-he matri* is initially laid do)n as unminerali2ed osteoid
• 5inerali2ation involves osteoblasts secreting vesiclescontaining al+aline "hos"hatase.
• -his cleaves the "hos"hate grou"s and acts as the (oci (orcalcium and "hos"hate de"osition.
• -he vesicles then ru"ture and act as a centre (or crystals
to gro) on.
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MEC*ANISM OF &ONE %RO+T*
-here are three basic mechanisms by )hich gro)th ta+es"lace at the cellularHtissue level. -hey are?
M :y"er"lasia ? Gro)th due to increase in number o( cells.
M :y"ertro"hy ? Gro)th due to increase in si2e o( the cells.
M E*tracellular 5atri* 4ecretion ? In this "rocess there
is increase in si2e because o( the secretions o( thecells into the e*tracellular matri*
Post natal gro)th o( bone ta+es "lace in the (ollo)ing
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Post natal gro)th o( bone ta+es "lace in the (ollo)ingthree )ays?
M Chondral gro)th6achieved by interstitial gro)th o(cartilage originating in cartilage. E*am"le includessynchondroses.
M 4utural gro)th is a""ositional gro)th and occurs inthe s+ull and (acial sutures on the edge o( bones.
M Periosteal gro)th )hich is also a""ositional and occursin the "eriosteum. Periosteal gro)th unli+e the
chondral and sutural gro)th continues into advancedage.
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5EC:ANI45 O9 BONE G;O'-:
5odeling and remodeling7ri(t7is"lacement
Primary4econdary
-rabecular and cortical bone gro) ada"t and turn over bymeans o( t)o (undamentally distinct mechanisms modelingand remodeling.
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• Bone modeling is a mechanically mediated ada"tive"rocess (or changing a bones si2e sha"e or "osition.
• It is an uncou"led "rocess meaning anabolic and catabolicsites are controlled inde"endently.
• Its an im"ortant element o( s+eletal gro)th (unctions asa li(elong o"timi2ation "rocess (or ada"ting bone mass andarchitecture to (unctional needs.
• 5odeling also called as macro modeling by some authors is
an activity "rimarily (ound during gro)th and is res"onsible(or the (inal sha"e o( the bones.
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• Bone remodeling is the "hysiologic term (or internalturnover o( a minerali2ed tissue )ithout a change in its
overall (orm.
• It is a cou"led se!uence o( catabolic resor"tiveF andanabolic osteogenicF events to su""ort calcium homeostasisand re"air rene)F aged or damaged minerali2ed tissue.
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• Both modeling and remodeling are the result o( thecontrolled activity o( osteoblasts and osteoclasts.
• -he di((erence is in modeling both these t)o cells actover a large sur(ace area removing or (orming largevolumes o( bone mass )hich is active during gro)th "eriod.
• ;emodeling on the other hand is active throughout li(e and
serves to modi(y sha"e o( s+eleton architecture bonevolume and to re"air microdamage.
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+)'ff,s 'a- is a theory develo"ed by the German
anatomist and surgeon Uulius 'ol((/3L&/J$1F
It that states that bone in a healthy "erson or animal )illada"t to the loads under )hich it is "laced.
I( loading on a "articular bone increases the bone )illremodel itsel( over time to become stronger to resist thatsort o( loading.
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-he internal architecture o( the trabeculae undergoes
ada"tive changes (ollo)ed by secondary changes to thee*ternal cortical "ortion o( the boneV "erha"s becomingthic+er as a result.
-he inverse is true as )ell? i( the loading on a bonedecreases the bone )ill become )ea+er due to turnover.
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• Cortical dri(t is gro)th movement relocation or
shi(tingF o( an enlarging "ortion o( a bone by theremodeling action o( its osteogenic tissues.
• -he cortical "late can be relocated by simultaneousa""osition and resor"tion "rocesses on the o""osing
"eriosteal and endosteal sur(aces
• -he bony cortical "late dri(ts by de"ositing and resorbingbone substance on the outer and inner sur(aces
res"ectively in the direction o( gro)th.
• I( resor"tion and de"osition ta+e "lace at the same rate
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" " " the thic+ness o( the bone remains constant. i( more boneis de"osited than resorbed the thic+ness o( the structure
increases
• 7uring the develo"mental "eriod de"osition ta+es "lace ata slightly (aster rate than resor"tion so that the individualbones slo)ly enlarge.
7i l
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7is"lacement
• 7is"lacement is movement o( the )hole bone as a unit.
• It is a translatory movement o( the )hole bone caused bythe surrounding "hysical (orces and is the second
characteristic mechanism o( s+ull gro)th• -)o ty"es
• Primary dis"lacement• 4econdary dis"lacement
Primary dis"lacement
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• As a bone enlarges it is simultaneously carried a)ay (romthe other bones in direct contact )ith it.
• -his creates s"ace )ithin )hich bony enlargement ta+es"lace.
•
It is the "hysical movement o( the )hole bone as thebone gro)s and remodels by resor"tion and a""osition.
4econdary dis"lacement
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4econdary dis"lacement
• It is the movement o( a )hole bone caused by the
se"arate enlargement o( other bones )hich may be nearbyor !uite distant.
• It is the movement o( bone related to enlargement o(
other bones.
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CA;-I8AGE
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•
Cartilage is a s"ecial ty"e o( connective tissue that has asti(( (irm but not hard intercellular matri*.
• It "rovides rigid su""ort but it is so so(t that it can becut )ith a (ingernail.
• Cartilage is a nonvascular connective tissue and it isordinarily noncalci(ied.
• Cartilage is com"osed o( cells and an intercellular matri*containing (ibers and ground substance.
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9unctions o( cartilage
• 9le*ible su""ort in a""ro"riate anatomic "laces the nasal
ti" ear lobe thoracic cage tracheal ringsF
• Pressure tolerant tissue located in s"eci(ic s+eletal areas
)here direct "ressure occurs articular cartilageF
• Gro)th cartilage in conjunction )ith certain enlargingbones synchondrosis condylar cartilage e"i"hyseal "lateF.
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Inter cellular matri*
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• ;ich in "roteoglycans consisting o( a core "rotien6
+eratin sul(ate or chondrotin sul(ate )ith numerous
glycosaminoglycans attached around it in bottle brush
"attern
• Proteoglycans themselves are attatched by hyaluronic
acid.
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• Bet)een &$ and 3$ "ercent o( the net )eight o(
cartilage is )ater and this large com"onent o( )ateraccounts (or the resilient nature o( cartilage.
• 'ater is attracted to the negative charges in the
abundant sul(ate and carbo*yl grou"s on the GAGs.
• -his hydration "ermits di((usion o( )ater6solublemolecules in the ground substance.
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Perichondrium
• :as 1 layers?
E*ternal 6 (ibrous made o(dense irregular connective
tissueInternal 6 cellularchondrogenicF contains many(ibroblasts and blood
• 9unctions? cartilage nutritiona""ositional gro)th andregeneration
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Chondroblast
• 8ess di((erentiated cartilagecell
• Originate (rom non6
di((erentiated mesenchyme.
• :ave a (lattened sha"e
• A )ell6develo"ed roughendo"lasmic reticulum in abaso"hilic cyto"lasm Cb Chondroblasts
PC 6 Perichondrium
Chondrocyte
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Chondrocyte
• Chondroblasts mature intochondrocytes
• 7i((erentiated cartilage cells
• 'ith advancing cellular agechondrocytes "rogressively losetheir rough endo"lasmicreticulum
• Chondrocytes reside in thede"th o( matri* 6 )ithin minutes"ecial cavities lacunaes
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-y"es o( cartilage
-here are three +inds o( cartilage de"ending u"on the
amount and nature o( (ibers in the connective tissue
6 :yaline cartilage
6 Elastic cartilage
6 9ibro cartilage
:yaline cartilage
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:yaline cartilage
• 9ine collagen (ibers dis"ersed throughout the ground
substance
• 5ost abundant cartilage
• 9ound in joints )here it covers the ends o( bones
)ith a smooth sur(ace
• Involved in bone (ormation and gro)th
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• Amor"hous (irm matri* )ithim"erce"tible net)or+ o(collagen (ibers
• Chondrocytes lie in lacunae
• 4u""orts rein(orces cushionsand resists com"ression
• 9orms the costal cartilage
• 9ound in embryonic s+eletonend o( long bones nose tracheaand laryn*
El stic c til
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Elastic cartilage
• :as elastic (ibers
• Can be bent and then resume
its original sha"e
• 9ound in the e*ternal ear and e"iglottis
•
4imilar to hyaline cartilage but )ith more elastic (ibers
• 5aintains sha"e and structure )hile allo)ing (le*ibility
9ibrocartilage• :as more collagen (ibers than hyaline cartilage
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• :as more collagen (ibers than hyaline cartilage
• 9ibers are organi2ed into bundles
• 9ound bet)een vertebrae in the +nee "ubic sym"hyses
-5U
• 5atri* similar to hyaline cartilage but less (irm )ith
thic+ collagen (ibers
• Provides tensile strength and absorbs com"ression shoc+
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Articular Cartilage
•
It is a s"ecialised (orm o( hyalinecartilage
• It is not surrounded by a"erichondrium and is "artly
vascularised
• -rans(orms the articulating endso( the bones into lubricated)ear6"roo( slightly com"ressible
sur(aces )hich e*hibit very little(riction
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•
-he main source o( nourishment(or articular cartilage is thesynovial (luid )hich (ills the
joint cavity.
•
Additional small amounts o(nutrients are derived (rom bloodvessels that course through thecalci(ied cartilage close to thebone.
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Primary Cartilage
• -hey are derivatives o( "rimordial cartilage.
• In "rimary cartilage chondroblasts divide and
synthesi2e intercellular matri*.
• -he dividing chondroblasts are surrounded bycartilaginous matri*.
• Cells arranged in columnar (ashion
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• 4ince surrounded by cartilaginous matri* "rimarycartilage is not in(luenced by local environmental(actors.
• Gro)th is interstitial. :ence L dimensional gro)th
• Considered to be a genetic "acema+er (or gro)th.
4econdary cartilage
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• 4econdary cartilage (orms on a membranous bone
• No intercellular matri*
• Not surrounded by cartilaginous matri*
• Cells are arranged in ha"ha2ard manner
• A((ected by e*ternal in(luences )hich )ill stimulategro)th o( cartilage e.g. condylar cartilage
• Only "eri"heral gro)th ta+es "lace
• Contributes only to regional ada"tive gro)th
4 h d i
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4ynchondrosis
•
-he structure in the cranial base )hich resemblesthe gro)th "lates are synchondroses.
• A synchondrosis is a ty"e o( immovable joint in
)hich the articulating structures are joinedtogether by hyaline cartilage.
• 4ynchondroses are (ormed bet)een the e"i"hysesendsF and dia"hyses sha(tsF o( long bones
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• It includes the numerous tem"orary cartilaginous junctions bet)een dia"hysis and e"i"hysis in the
immature "ost cranial s+eleton and also in theregions o( unossi(ied cartilage bet)een s+ullcom"onents develo"ing in the chondrocranium.
7iagrammatic re"resentation o(synchondrosis
Nasal Cartilage
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• Nasal cartilage is a thin cartilaginous "late located
bet)een vomer "er"endicular "late o( the ethmoid andnasal bone
• It "rovides a thrusting (orce )hich carries the ma*illa
(or)ard and do)n)ard during gro)th.
Cross section o( nasal cartilage
Condylar Cartilage
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Condylar Cartilage
•
-he condylar cartilage is a secondary ty"e o(cartilage )hich )as trans(ormed "hylogenetically(rom the "eriosteum
• -his cartilage is not a "art o( the 5ec+els cartilage
• -he condylar cartilage gro)s not nterstitiallybuta""ositionally.
CARTI!A%E AN$ &ONE STRUCTURE COMPARE$#
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• Both o( these tissues re"resent s"eciali2ed s+eletalvariations o( ordinary connective tissue and theirres"ective (eatures sho) a number o( structuralsimilarities.
• Both are com"osed o( connective tissue cells )ith an
intercellular matri* containing collagenous (ibers andground substance.
• -hey both have an enclosing vascular membrane and this
covering tissue is characteri2ed by a mar+ed gro)th"otential.
.
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• -he matrices o( cartilage and bone are rece"tive to
calci(ication although cartilage sho)s much variabilityin this regard.
• -he (irm rigidity o( both tissues is ada"ted to
(unctions o( su""ort
• Cartilage is noncalci(ied.
• Dascular canal system is lac+ing in cartilage direct
di((usion through its so(t matri* readily occurs.
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• E*trinsic "ressures may be involved in the many(unctional relationshi"s o( cartilage the lac+ o( blood
vessels )ithin this tissue is an ada"tation to the so(tnature o( its matri*.
• Bone in contrast has a calci(ied matri* housing a system
o( rigid6)alled vascular canals )ith their continuingelaborate net)or+ o( canalicular channels.
• Cartilage utili2es both a""ositional and interstitial"rocesses o( gro)th. Bone ho)ever can enlarge only by
an a""ositional mode o( gro)th
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Conclusion
Eugene ;oberts re(erred orthodontists ascranio(acial bone s"ecialists and hence a thorough+no)ledge about bone and cartilage )ill hel" theorthodontist to deal )ith the "atients moree((ectively and e((iciently.
;e(erences
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• 9acial gro)th?Enlo) Lrd edition
• Grays anatomy ?Lrd edition.
• Orban@s Oral :istology , Embryology /1th edt.
• -. 5 . Graber ;.8. Danarsdall orthodontics current"rinci"les and techni!ues Lrd edition
• -e*tboo+ o( cranio(acial gro)th 4ridhar Prem+umar
• 4cienti(ic american understanding origins? se" 1$$J?"gS#
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• :arold 5. 9rost A 1$$L u"date o( bone "hysiologyand )ol((@s la) (or cliniciansangle orthodontist vol
S% no / 1$$%
• '. Eugene roberts etal bone modeling? biomechanicsmolecular mechanisms and clinical "ers"ectives
seminars in orthodontics vol /$ no 1 juneF 1$$%? ""/1L6/&/
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-han+ you…………….