chapter  2
14 Pages

What are bones and teeth?

GENERALSTRUCTUREOF BONE(fig.2.1) Bonesareeithercylindrical(longbonesofthelimbs), flat(skull,girdles,ribs)orirregular(vertebrae)in shape.Whensectionedlongitudinally,alongboneof anadultmammalconsistsofacylinderofdense (compactorcortical)bone,withspongy(trabecular orcancellous)boneateitherend,andaninternal marrowcavity.Surroundingtheoutsideoftheshaft isamembrane-theperiosteum-whichcontinues aroundthesynovial,orjointcavity(wheretwobones articulate).Thusthearticularendofalongboneisnot coveredbyperiosteum,butbyathinlayerof cartilageprovidingafrictionlesssurfaceforarticulation.Thewholejointisbathedbysynovialfluid, containedwithinthesynovialcavity.