OSTEOLOGYHumanAnatomyUnit1

InAnatomyToday

FunctionsoftheSkeletalSystem

• Mechanicalsupportformovement• Protectionofinternalorgans• Hemopoiesis• Homeostasis• Mineralhomeostasis• Electrolytebalance(Ca2+/PO4

-3)• Acid-basebalance

• Storageofheavymetals• Cadmium,Nickel,Mercury,Chromium,Lead,Aluminum,Titanium,Iron,Arsenic

BoneTissue

• OsseousTissue• Adynamictissuethatisconstantlyremodeled• Oldbonetissueisdegraded• Newbonetissueisproduced

• Classifiedasaconnectivetissue• Bonetissueismadeupofdifferenttypesofbonecellsandbonematrix• 2typesofbonetissue

• Spongybonetissue• Compactbonetissue

BoneCellTypes

• Osteoprogenitor Cells• Stemcells• Linetheinnerperiosteum• Producenewbonecellsthroughmitosis

• Osteoblasts• Newlyformedbonecells• Secretematrix• Highmetabolicrate• Osteoblastsbecometrappedinlacunae

• Osteocytes• Maturebonecells• Highlybranched• Surroundedbymatrix• Lowmetabolicrate

• Boneliningcells• linethesurfaceofbones• regulatecalciumandphosphoruspassage

• Osteoclasts• fixedmacrophage• Breakdownbonematrix

BoneCellTypes

BoneMatrix

• Organiccomponent∼ 30%byweight• Calledosteoid• PredominantlycomprisedofaproteincalledtypeIcollagenfibers∼ 90%

• Non-collagenousproteins∼ 10%• Over30types• Proteoglycans• Glycoproteins

• Inorganiccomponent∼ 60%byweight• Saltsandminerals• 85%Hydroxyapatitecrystals

• Ca10(PO4)6(OH)2• 10%CaCO3• Otherminerals

• Mg,Na,K,Fl,etc.

• Water∼ 10%byweight

SpongyBoneTissueCancellousBoneTissue

• Firstbonetissuepresentduringbonedevelopment• Madeupoftrabeculae• Latticeofthinplates• Trabeculaelaiddownbasedonlinesofforce

• Spongyboneisporous• Decreasestheweightofboneswithoutcompromisingstrength

• The“pores”arefilledwithredbonemarrow

CompactBoneTissue

• Solidbonetissue• Noporespresent

• Madeupofmanyosteons• Haversiancanalsystem• Osteonsrunparalleltotheaxisofthebone

• Bonetissueisarrangedinlamellaearoundacentralcanal

• Centralcanalprovidearouteforbloodvessels/lymphatics/nerves• Runparalleltotheaxisofthebone

• Perforatingcanalsprovidearouteforbloodvessels/lymphatics/nerves• Perpendiculartotheaxisofthebone

HistologyofBoneTissue

SpongyBoneTissue CompactBoneTissue

BoneMarrow

• Bonemarrowfillsinthespaceinbones• Fillsinthe“pores”ofspongybone• Fillsthemarrow/medullarycavityoflongbones

• 2typesofbonemarrow• Redmarrow- hemopoiesis• Yellow/fattymarrow– fatstorage

• Distributionchangesasyougrow

GeneralClassificationofIndividualBones

• Byshape• Long• Short• Flat• Irregular

• Bydevelopmentallocation• Withinatendon• Withinasuture

LongBones

• Characteristics• Supporttheweightofthebody• Providemovement• Haveamarrowcavity

• Longbonesinthehumanbody• Humerus• Radius• Ulna• Femur• Tibia• Fibula• Metacarpals,metatarsals• Phalanges

ShortBones

• Characteristics– Cubeshaped– Providesupportandstability– Onlyasmallamountofmovementbetweenshortbones

• Shortbonesinthehumanbody– Carpals– Tarsals

FlatBones

• Characteristics• Broad,flatsurface(s)formuscleattachment• Providephysicalprotectionforinternalorgans

• FlatbonesinthehumanbodyFrontal Vomer

Parietal Sternum

Occipital Ribs

Nasal Scapula

Lacrimal Ilium

IrregularBones

• Characteristics– Variedshapes– Prominentsurfaces

• IrregularbonesinthehumanbodyVertebrae Zygomatic

Sacrum Maxilla

Coccyx Mandible

Temporal Palatine

Sphenoid Inferiornasalconcha

Ethmoid Hyoid

SesamoidBones

• Characteristics• Abonethatcompletelyorpartiallyembeddedwithintendons

• Small• Round(ish)• Reducefrictionoftendonsatjointsurfaces

• Protecttendonsfromdirecttrauma• Exampleinthehumanbody

• Patella• Bonesintheballofthefoot

• Calledsesamoidbones• Beneaththehallux• VariableinotherMTPjoints

SuturalBones(Wormian Bones)

• Characteristics• Extrabones/piecesthatdevelopwithinasutureintheskull• Possiblylinkedtorapidskullexpansion• Small• Foundmorecommonlyinmalesthanfemales