Skeletal System - Human Anatomy part 2 PDF

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Skeletal System part 2 summary...

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Sphe noi dBone Theba t s ha pe ds phe noi dbones pa nst hewi dt hoft he mi d dl ec r a ni a lf os s a . Thes phe noi di sc ons i de r e dt he k e y s t on eoft hec r a ni umbe c a us ei tf or msac e nt r a lwe d g e t ha ta r t i c ul a t e swi t ha l lot he rc r a ni a lb one s . I ti sa c ha l l e n gi n gbonet os t ud ybe c a us eofi t sc ompl e xs h a pe . I t c ons i s t so fac e nt r a lbod ya ndt hr e epa i r sofpr oc e s s e s :t h e gr e a t e rwi n g s , l e s s e rwi n gs , a ndp t e r y g oi dp r oc e s s e s . Wi t hi nt hebodyo ft hes phe no i da r et hepa i r e ds phe noi da l s i nus e s . Th es u pe r i ors ur f a c eoft hebo dybe a r sas a d dl e s h a pe d pr omi ne nc e , t hes e l l at ur c i c a, me a ni n g“ Tur k ’ ss a ddl e . ” Th es e a toft hi ss a ddl e , c a l l e dt hehy pophy s e alf os s a, f or msas nuge nc l os ur ef ort hepi t ui t a r ygl a n d ( h ypo ph y s i s ) .

Th eopt i cc anal sl i ea nt e r i ort ot hes e l l at ur c i c a ;t he ya l l o wt heopt i cne r v e s( c r a ni a lne r v e sI I )t opa s st o t hee y e s . One a c hs i deoft hes phe noi dbod yi sac r e s c e nt s ha pe dr o woff ouro pe ni n g s .Th ea nt e r i or mos tof t he s e , t hes upe r i oror bi t alfis s ur e ,i sal on gs l i tbe t we e nt h egr e a t e ra ndl e s s e rwi n gs . I ta l l o wsc r a ni a l ne r v e st ha tc ont r ole y emo v e me n t s( I I I , I V, VI )t oe nt e rt heor bi t . Thi sfis s ur ei smos t ob vi ousi na na nt e r i or v i e woft hes kul l . Th ef o r ame nr ot undum a ndf or ame no v al epr o v i depa s s a g e wa y sf orb r a nc he so fc r a ni a l ne r v eVt or e a c ht hef a c e . Thef or a me nr o t undumi si nt heme di a lpa r toft hegr e a t e rwi n ga ndi sus ua l l y o v a l , de s pi t ei t sn a meme a ni n g“ r ou ndope ni n g . ”Thef or a me no v a l e , al a r g e , o v a lf o r a me np os t e r i ort ot he f or a me nr o t u ndum, i sa l s ovi s i bl ei na ni nf e r i or v i e woft hes kul l . Pos t e r o l a t e r a lt ot hef or a me n o v a l ei st hes ma l lf or ame ns pi nos um;i t t r a ns mi t st hemi ddl eme ni ng e alar t e r y ,whi c h s e r v e st h ei nt e r n a lf a c e so fs omec r a ni a lbone s .

Et hmoi dBone Li k et het e mp or a la nds ph e noi dbone s , t hede l i c a t ee t hmoi dboneha sac ompl e xs ha pe .Lyi n gbe t we e nt h e s p he noi da ndt hen a s a lbone so ft hef a c e , i ti st hemos tde e pl ys i t ua t e dboneo ft hes kul l . I tf or msmo s tof t hebon ya r e abe t we e nt hena s a lc a vi t ya ndt heor bi t s . Th es u pe r i ors ur f a c eoft hee t h moi di sf or me db yt h epa i r e dhor i z ont a lc r i br i f or m pl at e s , whi c hhe l pf or m t her oofoft hena s a lc a v i t ya ndt heflooroft hea nt e r i orc r a ni a lf os s a .Th ec r i br i f or mpl a t e sa r epu nc t ur e d b yt i n yhol e sc a l l e dc r i br i f or mf or ami nat ha ta l l o wt hefil a me nt soft heol f a c t or yne r v e st opa s sf r omt he s me l lr e c e pt or si nt hena s a lc a vi t yt ot hebr a i n. Pr o j e c t i n gs u pe r i or l ybe t we e nt hec r i br i f or mpl a t e si sa t r i a n gul a rpr oc e s sc a l l e dt hec r i s t agal l i .Theo ut e r mos tc o v e r i n goft hebr a i n( t hedur ama t e r )a t t a c he st o t hec r i s t ag a l l ia ndhe l pss e c ur et hebr a i ni nt h ec r a ni a lc a vi t y . Th epe r pe ndi c ul arpl at eoft hee t hmoi dbonep r o j e c t si nf e r i or l yi nt heme di a npl a nea ndf or mst he s upe r i orpa r to ft hena s a ls e pt um, whi c hdi vi de st h en a s a lc a v i t yi nt or i ghta ndl e f tha l v e s . Fl a nki n gt h e pe r p e ndi c ul a rpl a t eone a c hs i dei sal a t e r almas sr i ddl e dwi t hs i n us e sc a l l e de t hmoi dalai rc e l l s , f or whi c ht hebon ei t s e l fi sna me d( e t hmos=s i e v e ) . Ext e ndi n gme di a l l yf r omt hel a t e r a lma s s e s , t hede l i c a t e l y c oi l e ds upe r i o ra n dmi ddl enas alc onc hae , na me da f t e rt hec onc hs h e l l sf oun do nwa r moc e a nbe a c he s ,

pr ot r u dei nt ot hena s a lc a v i t y . Thel a t e r a ls ur f a c e soft hee t h moi d’ sl a t e r a lma s s e sa r ec a l l e dor bi t alpl at e s be c a us et he yc ont r i but et ot heme di a lwa l l soft heor bi t s . Sut ur alBo ne s Sut ur albone sa r et i n y , i r r e gul a r l ys ha pe dbone sorbon ec l us t e r st ha toc c urwi t hi ns u t ur e s , mos tof t e ni n t hel a mb doi ds ut ur e .Note v e r y oneha st he s ebone sa ndt he i rs i gni fic a nc ei sunkno wn.

Fac i alBone s Mandi bl e Th eUs ha pe dmandi bl e , orl o we rj a wbone , i st hel a r g e s t , s t r on g e s tbon eoft hef a c e .I t ha sabod y , whi c h f or mst hec hi n, a ndt woupr i ghtr a mi( r a mi=br a nc he s ) . Ea c hr a musme e t st hebo dyp os t e r i or l ya ta mandi bul arangl e . Att hes u pe r i orma r -gi no fe a c hr a musa r et wopr oc e s s e ss e pa r a t e db yt hemandi bul ar no t c h.Th ea nt e r i orc or onoi dpr oc e s si sa ni ns e r t i onpoi ntf ort hel a r g et e mpor a l i smu s c l et ha te l e v a t e st he l o we rj a wdur i ngc he wi n g . Thepos t e r i orc ondy l arpr oc e s sa r t i c ul a t e swi t ht hema ndi b ul a rf os s aoft he t e mp or a lbone , f or mi n gt het e mp or oma ndi bul arj oi ntont hes a mes i de . Maxi l l ar yBone s Th emaxi l l ar ybone s , orma xi l l ae ,a r ef us e dme di a l l y . The yf or mt heuppe rj a wa ndt hec e nt r a lpor t i onof t hef a c i a ls ke l e t on. Al lf a c i a lbone se x c e ptt hema ndi bl ea r t i c ul a t ewi t ht h ema xi l l a e . Fort hi sr e a s on, t he ma xi l l a ea r ec ons i de r e dt hek e y -s t onebone soft hef a c i a ls k e l e t on. Th ema xi l l a ec a r r yt h eu ppe rt e e t hi nt h e i ral v e ol arpr o-c e s s e s . J us ti nf e r i ort ot heno s et hema xi l l a eme e t me di a l l y , f or mi n gt hepoi nt e dant e r i ornas als pi nea tt h e i rj unc t i on. Thepal a t i nepr oc e s s e soft he ma xi l l a epr o j e c tpos t e r i or l yf r omt hea l v e ol a rpr o c e s s e sa ndf us eme di a l l ya tt hei nt e r -max i l l ar ys ut ur e , f or mi n gt hea nt e r i ort wot hi r dsoft heha r dpa l a t e , orbon yr oofoft hemout h.J us tpos t e r i ort ot het e e t h, a mi dl i nef or a me nc a l l e dt h ei nc i s i v ef os s al e a dsi nt ot hei nc i s i v ec anal , apa s s a g e wa yf orbl oodv e s s e l sa nd ne r v e s . Th ef r ont alpr oc e s s e se x t e nds upe r i or l yt ot hef r ont a lbone , f or mi n gpa r toft hel a t e r a la s pe c t so ft hebr i dg eoft henos e . Th er e gi on st ha tfla nkt hena s a lc a v i t yl a t e r a l l yc ont a i nt he maxi l l ar ys i nus e s , t hel a r g e s toft hepa r a na s a ls i nus e s . The y e x t e ndf r omt heor bi t st ot her oot soft heup pe rt e e t h.La t e r a l l y , t hema xi l l a ea r t i c ul a t ewi t ht hez y g oma t i cbone svi at he i r z y g omat i cpr oc e s s e s .

Zy g omat i cBone s Th ei r r e gul a r l ys ha pe dz y g oma t i cbone s , c ommonl yc a l l e dt hec he e kbo ne s , f or mt hepr omi ne nc e so ft he c he e ksa ndpa r toft hei nf e r ol a t e r a lma r gi nso ft heor b i t s . The ya r t i c ul a t ewi t ht h ez y g oma t i cpr oc e s s e sof t het e mpor a lb one spos t e r i or l y , wi t ht hez y g oma t i cpr oc e s s e soft hef r ont a lb ones upe r i or l y , a ndwi t ht h e z y g oma t i cpr o c e s s e soft hema xi l l a ea n t e r i or l y . Nas a lBone s

Th et hi n, ba s i c a l l yr e c t a n gul a rnas albone sa r ef us e dme di a l l y , f o r mi n gt hebr i dg eoft heno s e . The y a r t i c ul a t ewi t ht hef r ont a lbones upe r i or l y , t hema xi l l a r ybone sl a t e r a l l y , a ndt hepe r p e ndi c ul a rpl a t eoft he e t h moi dbonepos t e r i or l y . I nf e r i or l yt he ya t t a c ht ot h ec a r t i l a g e st ha tf or mmos toft hes k e l e t onoft he e x t e r na lnos e . Lac r i malBone s Th ede l i c a t e ,fing e r na i l s ha pe dl ac r i malbone sc ont r i but et ot heme di a lwa l l so fe a c hor bi t . The ya r t i c ul a t e wi t ht hef r ont a lbones upe r i or l y , t hee t hmoi dbonepos t e r i or l y , a ndt hema xi l l a ea nt e r i or l y . Ea c hl a c r i ma l bo nec ont a i nsade e pgr oo v et h a the l psf or mal ac r i malf os s a. Thel a c r i ma lf os s ahous e st hel ac r i mals ac , pa r toft hepa s s a g e wa yt ha ta l l o wst e a r st odr a i nf r omt hee y es ur f a c ei nt ot hena s a lc a v i t y( l ac r i ma=t e a r s ) . Pal at i neBone s Ea c hLs ha p e dpal at i nebonei sf a s hi one df r omt wobon ypl a t e s , t h ehor i z o nt ala ndpe r pe ndi c ul ar , a ndha s t hr e ei mpor t a nta r t i c ul a rpr oc e s s e s , t hepy r ami dal , s phe noi dal , a ndor b i t al . Thehor i z ont alpl a t e s , j oi ne d a tt heme di a npa l a t i nes ut ur e , c ompl e t et h ep os t e r i orpor t i onoft heha r dpa l a t e . Thes up e r i or l ypr o j e c t i n g pe r pe ndi c ul a r( v e r t i c al )pl at e sf o r mpa r to ft hepos t e r ol a t e r a lwa l l soft hena s a lc a v i t ya ndas ma l lpa r t of t heor b i t s . Vome r Th es l e nde r ,p l o ws ha pe dv ome rl i e si nt hena s a lc a vi t y , wh e r ei tf or msp a r to ft hena s a ls e pt um. I ti s de s c r i be dbe l o wi nc onne c t i onwi t ht hena s a lc a vi t y . I nf e r i orNas alConc hae Th epa i r e di nf e r i ornas a lc onc haea r et hi n, c ur v e dbo ne st ha tpr oj e c tme di a l l yf r omt hel a t e r a lwa l l so ft he na s a lc a v i t y , j us ti nf e r i ort ot hemi ddl ena s a lc onc ha eoft hee t hmoi dbone . The ya r et hel a r g e s toft het hr e e pa i r sofc o nc ha ea nd, l i k et heot he r s , t he yf or mpa r t oft hel a t e r a lwa l l soft hena s a lc a vi t y . TheHy oi dBone Th ou ghnotr e a l l ypa r to ft hes kul l , t hehy oi dbonel i e si nt hea nt e r i orne c kj us t i nf e r i ort ot hema ndi bl e , a ndl o oksl i k eami ni a t ur ev e r s i onofi t . Theh y oi dbone i suni q uei nt ha ti ti st heonl yboneoft hebod yt ha tdoe snota r t i c ul a t edi r e c t l y wi t ha n yot he rbo ne . I n s t e a d, i ti sa nc hor e db yt hena r r o ws t y l ohy oi dl i g ame nt st o t hes t y l oi dpr o-c e s s e soft het e mpor a lbo ne s . Hor s e s hoes ha pe d, wi t habo dya nd t wopa i r sofhor ns , orc or n ua, t heh y oi db onea c t sa samo v -a bl e ba s ef ort h et on gue . I t sb od ya ndgr e a t e rhor nsa r ea t t a c hme nt po i nt sf orne c kmus c l e st ha tr a i s ea ndl o we rt hel a r ynxdur i n g s wa l l o wi nga nds pe e c h. Spe c i alChar ac t e r i s t i c soft heOr bi t sa ndNas alCa vi t y Th eor bi t sa ndt hena s a lc a vi t ya r ef or me df r oma na ma z i ngn umbe r ofb one s . Ev e nt hou ghweh a v ea l r e a dyd e s c r i be dt he i ri ndi v i dua l bo ne s , wegi v eabr i e fs umma r yhe r et opul lt hepa r t st og e t he r . TheOr bi t s Th ec one s h a pe dor bi t sa r ebon yc a vi t i e si nwhi c ht hee y e sa r e fir ml ye nc a s e da ndc us hi one db yf a t t yt i s s ue . Themus c l e st h a t

mo v et hee y e sa ndt het e a r pr o duc i n gl a c r i ma lgl a nd sa r ea l s ohous e di nt heor b i t s .Th ewa l l sofe a c hor bi t a r ef or me db ypa r t so fs e v e nbone s —t hef r o nt a l , s phe n oi d, z y g oma t i c ,ma xi l l a , pa l a t i ne , l a c r i ma l , a nd e t h moi dbone s .

TheNas alCa v i t y Th enas a lc a vi t yi sc ons t r uc t e do fbonea ndh y a l i nec a r t i l a g e . Ther oof oft h en a s a lc a v i t yi sf or me db yt hec r i br i f or mpl a t e soft hee t hmoi d . Th el at e r a lwal l sa r el a r g e l ys h a pe db yt hes u pe r i ora ndmi ddl e c onc ha eoft hee t h moi dbone , t h epe r p e ndi c ul a rpl a t e soft hepa l a t i ne bo ne s , a ndt hei nf e r i orn a s a lc onc ha e . Thede pr e s s i onsunde rc o v e rof t hec onc ha eont hel a t e r a lwa l l sa r ec a l l e dme at us e s( s up e r i or , mi ddl e , a n di nf e r i or ) .Th efl ooroft h en a s a lc a v i t yi sf or me db yt h ep a l a t i ne pr oc e s s e so ft hema xi l l a ea ndt hepa l a t i n eb one s . Then a s a lc a v i t yi s di v i de di nt or i ghta n dl e f tpa r t sb yt henas als e pt um. Theb on ypor t i on oft h es e p t umi sf o r me db yt hev ome ri nf e r i or l ya ndt hepe r pe ndi c ul a r pl a t eoft hee t hmoi dbones upe r i or l y . As h e e tofc a r t i l a g ec a l l e dt h e s e pt alc a r t i l a g ec ompl e t e st h es e pt uma nt e r i or l y .

Par anas alSi nus e s Fi v es kul lb one s —t hef r ont a l , s phe noi d, e t hmoi d, a n dpa i r e dma xi l l a r ybone s — c ont a i nmuc os a l i ne d, a i r fil l e ds i nus e sc a l l e dpar anas als i nus e sbe c a us et he y c l us t e ra r oundt hena s a lc a v i t y . The s es i nus e sgi v et hebone sar a t he rmot he a t e n a p pe a r a nc eonXr a yi ma g e s . Sma l lope ni n g sc onn e c tt hes i nus e st ot hena s a lc a vi t ya nda c ta s“ t wowa ys t r e e t s ” : Ai re nt e r st hes i nus e sf r omt h en a s a lc a v i t y , a ndmuc usf or me db yt hes i nus mu c os a edr a i nsi nt ot hena s a lc a v i t y . Th emuc os ao ft hes i nus e sa l s ohe l pst owa r m a n dhumi di f yi ns p i r e da i r . Thepa r a na s a ls i nus e sl i ght e nt hes kul la nde nha nc et he r e s ona nc eoft hev oi c e ....