The Sectional Microanatomy Of The Optic Canal And Its Interior Structure

More and more trauma of prosopo-head result in the injuries ofON.And most of these injuries are the optic nerves in the OC. Thesurgical doctors of ear nose throat department must master theanatomy of the OC,its interior instructure and its neighbour instructurewhen they practice the OC decompression with endoscope and thenerosurgery doctors must master the skills too when they practice sellartumour operation by ways of nasal cavity.So more people think highly ofthe anatomy of the OC,its interior instructure and its neighbourinstructure.There are lots of disputes about the question.We researchthe question with skulls and brain specimens by ways of frozensection.and identify clearly the OC and its interior instructure.[Objective] To provide detailed anatomic knowledge for clinical doctorsof ear nose throat department on ON decompression and for clinicalneurosurgery on sellar tumour operation.To invoid extremely injuringimportant instructure of the OC and its interior instructure .To study themechanism of traumatic ON injury.[Methods and materials] We select 15 adult skulls,7 men'skullspecimen and 8 women' s skull specimen.,with no cranium and orbitaldisease and all of the optic canals and its neighbour instructure areintact..15 cadaver heads that had been inmerged in formalin liquid withno cranium and orbital disease.Firstly we observe construction of adultskulls'OC.we also observe the shape of the OC in cranium opening andorbit opening.We measure the length of the roof wall, the lower wall ,themedial wall and the lateral wall of the OC.With sliding caliper and thedatas are precise to 0.02mm.Secondly we open the cadaver heads thathad been inmerged in formalin liquid and removal frontal lobe. opticchiasm, ON and the cranium opening of the OC are revealed.We surveythe angle between bilateralis ON and the angle of ON and sagittalline.We observe the shape of the ON in the cranium opening, thejuncture of the middle and the last 1/3 of the OC,the middle of the OC,and in the orbit opening.We measure the width and the length of the ONin optic nerve chiasma and in the cranium opening meanwhile.Then wecalculate the CSA of the ON in the two location .Thirdly,we cut thecadaver heads through sagittal line.We observe the relation of theeminence of OC and the eminence of CA. in the lateral wall of thesphenoid sinus.Then we measure the distance of the two eminenceswith sliding caliper.Forthly,we removal the contents of the eyeballkeeping the intacts of ON and reveal the orbit opening of the OC.Weremovel the tissues in the distance of 0.02mm in the front of the orbitopening and in the behind of the cranium opening.Then we immerse thetissue specimens in the 4% paraform for one week.Then we take out ofthe specimens and immerse them in the hydrochloric acid for 15 daysfor decalcification.Then we immerse them in water to get rid ofacid.Following the performances,we cut down the lateral tissues of OCparalleling the latera wall of the ON.And we cut the remainingspecimens in average.We wash the specimens in PH7.4,O.lmol/LPBand immerse them in 30% cane sugar buffer solution until saturation for24 hour.The we embed the specimen with embedding liquid and thenfreeze them. These specimens are make into 50um paraffinembeddedclips with freezing microtome.And then half of them are corlored withcampeachy for 3-4 minutes,and then cleaned with water .Finally theyare make into tabellae adhaesivus.A half of them are corlored with waysof HE.The specimens corlored with campeachy are observed under thesomatotype microscope and are taken photographs.We observe therelation of the OA in the OC.We observe the shape of the OC in craniumopening, the juncture of the middle and the last 1/3 of the OC,the middleof the OC, and in the orbit opening.We observe the relation of the OAand ON in every location.We survey the width and the height;of the OCin the cranium opening and in the orbit opening.Meanwhile,we surveythe length of the roof wall and the height of the OC in the middle of theOC and in the juncture of the middle and the last 1/3 of the OC.Then wecalculate the CSA of the OC in every location.Then,we observe theshape of the ON in the juncture of the middle and the last 1/3 of theOC,the middle of the OC, and in the orbit opening.and calculate theCSA of the ON in every locatioin.After calculation we contrast them withthe CSA of OC in every location.Fivly,we measure the thickness ofevery wall in every site.Sixly We observe the construct of the opticnerve sheaths and the relation with OC under microscope.Finally,weanalyze the datas with SPSS software.[Results] OC lie in the rear of the orbital medial wall constituted oflesser wing of sphenoid bone and corpus ossis sphenoidalis,and it walkfrom inside-rear to outside-front.The roof wall of the OC is made up oflesser wing of sphenoid bone and cerebral dura mater falx.The medialwall is made up of the lateral wall of corpus ossis sphenoidalis.Theinferior wall is made up of the subiculum of the lesser wing of sphenoidbone.The lateral wall is made up of the base of anterior clinoidprocess.The average angle of the.central axis of the ON with the middleline.right is 38.12±2.78 degree,left is 37.20±3.76,the average anglebetween the medial border of ON and middle line right is43.00±1.73degree,left is 44.58±1.20degree,through T text we considerthe two angles of the right and the left ON have no diferrence.Thewideth of the optic chiasm is 12.43±2.90mm,and the heightis2.04±0.14mm.The shape of the ON is horizontal ellipse,and it'swideth change narrow from cranium opening to orbit opening.Thewideth of ON in orbit openning is minimum (3.51±0.06)mm,but theheight in the middle of OC is minimum(1.53±0.09)mm.The CSA of ONin cranium opening is maximum(61.79±4.18)mm2,and minimum(21.01±1.85)mm2 in the middle of the OC.The wideth of the OC islarger than it's height in the orbit opening,and the shape is verticalellipse.The CSA of the OC in the middle is smallest,and largest in theorbit openning.The volume contrast of the ON and the OC is smallest inthe cranium openning.Eminentia canalis optica lie in the anterior upsideof the lateral wall of the sphenoid sinus.and hug the roof wall.While theeminence of carotid artery lie in the middle upside of the lateral wall ofthe sphenoid sinus and the rear upside of the OC.The average distancebetween the eminentia canalis optica and the eminence of carotid arteryis (3.01±0.12)mm.The OC walk from interior upside to exteriordoweside.The medial wall of the OC is longest,and the inferior wall isthe shortest.The thickness of the last 1/3 site of the roof wall of the OCis thinnest. OA in the OC is under the ON or below the inside of the ONin the cranium openning,under the ON in the middle of the OC andbelow slightly the outside of the ON in the orbit openning.We shouldopen the middle of the medial wall and from the juncture of the middleand the last 1/3 of the OC to cranium openning of the roof wall in orderto decompression.Optic nerve sheath is the stretch of three meningesincluding cerebral dura mater ,arachnoid mater and cerebral piamater.And it encase the ON.The ON connect tightly to optic nervesheath through much connective tissue trabeculum.[Conclusion] The thickness of the juncture of the middle and the last1/3 of the roof wall of the OC is thinnest. The average distance ofbetween the eminentia canalis optica and the eminence of carotid arteryis 3.01±0.12mm. The main reason of the nmechanism of the traumaticOC injury is that the ON connect tightly to optic nerve sheath throughmuch connective tissue trabeculum,and the ON is dragger by abruptoutside force.OA in the OC is under the ON or below the inside of ON inthe cranium openning,under the ON in the middle of the OC and belowslightly the outside of the ON in the orbit openning. We should open themiddle of the medial wall and from the juncture of the middle and thelast 1/3 of the OC to cranium openning of the roof wall when we practiceOC decompression operation.