Anatomy Study Of Temporal Bone Structure In The Surgery Of Cochlear Implantation Through Facial Recess Approach And Recondition Facial Nerve By Changing Its Course In Temporal Bone

Objective:To study the microanatomy of middle ear and its adjacent structures in the surgery of cochlear implantation through facial recess approach and anastomosis facial nerve by changing its course in temporal bone,in order to provide the anatomy data for clinical operation.Methods:forty human temporal bones of 20 specimens(40 temporal bones) were dissected,relative anatomical data of cochlear operation were observed and measured under operating microscope through posterior tympanum approach entering posterior tympanum;the course of facial nerve were changed through tympanic cavity.the extended portion of facial nerve was microscopically measured.Results:the average distances from suprameatal spine to short crus of incus was 19.14±0.89mm, from suprameatal spine to pyramid segment of facial canal was 16.30±1.09mm;the average distances from pyramid segment of facial canal to the surface of mastoid,crotch of chorda tympani nerve,posterior wall of auditory meatus were 20.84±1.13mm,11.2811.28±1.54mm,4.404.40±0.43mm,the average distance from pyramidal eminence to the anterior lip of round window niche was 4.46±0.76mm, from oval window to round window niche was 3.74±0.37mm,from incudostapedial joint to round window niche was 3.80±0.63mm;the included angle of chorda tympani nerve and facial nerve in the perpendicular paragraph was 24.8±4.7°,the included angle of horizontal semicircular canal and facial nerve in the level paragraph was 17.5±3.8°,the included angle of long process of incus and incus buttress was 46.0±7.1°.the average length of facial nerve in the level paragraph was about 11.60±0.80mm,the average length of facial nerve in the perpendicular paragraph was about 15.30±1.32mm,the included angle of facial nerve in the level paragraph and facial nerve in the perpendicular paragraph was 110.4±6.9°,the distance from stylomastoid foramen to geniculate ganglion was 22.06±1.40mm,the minimal extended length was 4.00mm,the maximal extended length was 7.32mm after changed the course of facial nerve in tympanic cavity.Conclusion:the position of anatomic structure in middle ear such as suprameatal spine,short crus of incus,horizontal semicircular canal,pyramidal eminence,cochleariform process is constant,especially the anatomic landmark of horizontal semicircular canal and pyramidal eminence,those landmarks can provide based on operation for middle ear;it is important procedure to find the round window and round window niche in operation of cochlear implantation,the oval window is a very important landmark for identify the round wingdow,the distance of round window niche and its adjacent structures changes in limit scope,the datas between the round window niche its adjacent structures could help us to determine the position of drill hole of cochlear implantation;the course of facial nerve in temporal bone is very important in clinical operations,it is applicable to repair the facial nerve defect by change the facial nerve course in tympanic cavity. the minimal extended length was 4.00mm,the maximal extended length was 7.32mm.the anatomy structures in temporal bone are complicated,the operater should be practiced in operational technique and master a great deal of anatomical knowledge,meanwhile,it is necessary to vary according to imageology and individual in practice.