| Objective:Meeting the needs of the clinical operation, we validate the feasibility and security of the transnasal endoscopic optic canal decompression through the applied anatomy study on the optic canal. And we measure reliable anatomic data needed by the operation, and provide the safe scope about the approach so as to enhance the successful ratio of the clinic opteration and prevent the complications .we may also cultivate the transnasal endoscopic approach skill on the cadaveric skull. Materials and methods:1.The first study was conducted on 8 sides of adult skull bones, randomly. After sawed , the bones was decalcified with 10% hydrochloric acid. And observe the anatomy of the specimens such as superior wall of the orbit ,the roof wall of sphenoid and ethmoid and the roof wall of the optical canal. Measure and observe them with the tool including dividers and vernier caliper, and snap with digital camera.2. The second study was conducted on 12 sides of cadaveric skulls, randomly. Decalcified with 10% hydrochloric acid, we cut these heads along the line of the horizontal plane on the superciliary arch about 1cm and brain tissues were removed. we measured the distance of the varial anatomic landmark, the angle of the elevation and the lateral deviation. Study the anatomic and variation condition between the posterior ethmoid sinus, sphenoid sinus and optic canal. At the same time, we measure and observe them with the tool including dividers and vernier caliper, and snap with digital camera.3. At the same time , 12 sides of cadaveric skulls were scanned via CT(GE, Japan) with coronal and axial plane according to the Frankfurt-Virchow plane. The CT images were treated. Results:1. Result from the measure to the skull bone {X ±SD) :(1) the width andthe height of the intracranial opening of the optic canal are 9.45+ 0. 76 mm and 5. 20 + 0. 65 mm, (2) the width and the height of the intraobital opening of the optic canal are 5.28 + 0.62 mm and 6. 91 + 0. 85mm, (3) the length and thickness of the optic roof wall of the optic canal are 9.69 ±1.64 mm and 2.09 + 0.47 mm, (4)the length and thickness of the optic lateral wall of the optic canal are 6.11 + 1.73 mm and 1.73 + 0.25 mm, (5)the length and thickness of the optic medial wall of the optic canal are 9. 81 + 1. 67 mm and 2. 23±0. 39 mm, (6)the length of the optic floor wall of the optic canal is 3. 68±0. 66 mm, (7)The distance from anterior nasal spine to orbital opening of optic canal is 65. 60 + 1. 38 mm,(8)The distance from anterior nasal spine to the cranial opening is 66.89+1.83 mm, (9)the distance of the foreside insertion of the middle concha to the medial wall of the middle part in the optic canal is 34.52 + 1.23 mm, Q0)the distance of the foreside insertion of the inferior concha to the medial wall of the middle part in the optic canal is 52.77 + 2.62 mm, (lDthe distance of the opening of the sphenoid to the medial wall of the middle part in the optic canal is 10.63 + 1.03 mm, 03the angle between the mediate axle of optic canal and the cranial media line of sagittal plane is 29.61° +1.25° , Q3)the angle of lateral deviation from the sagittal median line which crossed anterior nasal spine to the top of orbital opening's lateral border is 11.13° +0.79° , 04)the angle ofelevation from floor of nose to line which crossed anterior nasal spine to the top of orbital opening's lateral border is 39.10° ±1.07° , 05) the angle of elevation from floor of nose to line which crossed anterior nasal spine to the top of intracranial opening' s lateral border is 36. 98 ° ±1.07° .2. Result from the measures to the cadaveric skulls(X + SD) :(1) thewidth and the height of the intracranial opening of the optic canal are 9.94+1.73 mm and 6.65 + 2.04 mm, (2) the width and the height of the intraobital opening of the optic canal are 8. 27 + 1. 55 mm and 6. 04+1. 64 mm, (3) the length and thickness of the optic roof wall of the optic canal are 13. 77 + 1. 16 mm and 4. 13 + 1. 60 mm, (4) the length and thickness of the optic lateral wall of the optic canal are 15.64 + 1.77 mm and 4.41 + 2.24 mm, (5) the length and thickness of the optic medial wall of the optic canal are 15. 04 + 1. 90 mm and 2.16 + 0. 44 mm, (6) The distance from anterior nasal spine to orbital opening of optic canal is 69. 47 + 7. 51 mm, (7) The distance from anterior nasal spine to the cranial opening is 78.89+ 6. 11 mm, (8) the distance of the foreside insertion of the middle concha to the medial wall of the middle part in the optic canal is 34.99 + 2.32 mm, (9) the distance of the foreside insertion of the inferior concha to the medial wall of the middle part in the optic canal is 48. 53 + 4. 42 mm, (10) the distance of the opening of the sphenoid to the medial wall of the middle part in the optic canal is 13.91 + 1.70 mm, GD the distance from the anterior nasal spine to the middle of the uncinate is 37. 69 + 3. 94 mm, (12) the distance from the anterior nasal spine to the foreside insertion of the middle concha is 31.50 + 8.09 mm, (13) the distance from the anterior nasal spine to the middle of the ethmoidal bulla is 40.68±4. 33 mm, 04) the distance from the anterior nasal spine to opening of sphenoid is 53. 29±6. 46 mm, (15) the angle between the mediate axle of optic canal and the cranial media line of sagittal plane is 24.71° ±8.71° , 06)the angle of lateral deviation from the sagittal median line which crossed anterior nasal spine to the top of orbital opening' s lateral border is 11. 58° ±2. 39° , 07) the angle of elevation from floor of nose to line which crossed anterior nasal spine to the top of orbital opening' s lateral border is 36. 75° ±15.47° , (18) the angle of elevation from floor of nose to line which crossed anterior nasal spine to the top of intracranial opening's lateral border is 47.25° ±6.28° , 09) the distance adjoining the posterior ethmoid is 7.91 ± 2. 13 mm, CO) the distance adjoining the sphenoid is 6. 71 ±1.04 mm. 3.12 sides of cadaveric skulls were scanned via CT(GE, Japan) with coronal and axial plane according to the Frankfurt-Virchow plane. The CT images can show clearly and whole the characteristic of the optic canal. Conclusion:By researching and observing to the applied anatomy of the optic canal and discussing the surgical approach shows the transnasal endoscopic optic canal is a very efficient micro-hurt operation.(1) The optic canal is the channel between the skull and orbit, lie in the two roots of the sphenoid' s minor ala . The intracanaial opening shows horizontal-oval, the obital opening shows vertical-oval. The optic media wall is thinnest. It is easy to carry the optic canal decompression by the optical media wall. In the research, the presence ratio of the optic carina is about 60%. It is advantage to identify the optical canal on the lateral wall of sphenoid sinus.(2) The optic canal decompression adopts the Messerklinger approach.j j ?y i >/ uWe ablate uncinate process, open the ethmoid sinus and sphenoid sinus, and find the optic carina, and unclose the optic canal at the middle part of the optic canal, and slice the common tendinous ring, and decompress fully the optic canal.(3) The operator should know well the safe boundary on all anatomies. In the research, the anterior nasal spine regarding as the anatomical landmark, the depth of the middle part of the optic canal is between 67. 37 mm to 80.99 mm, the range of the elevating angle is between 31.28° to 53. 53° , and the ranges of the distance of lateral deviation and the angle of lateral deviation are respectively between 12. 2 mm to 15. 6 mm and 9. 19 ° to 13.97° these data may make us avoid damaging the internal carotid, cavernous sinus and the skull nerves. In the research, add to measure the elevating angle , the lateral deviation angle and distance, so as to ensure the range of depth and angle of the middle part of the optic canal, and decrease the occurance of the complication of the optic canal decompression.(4) We make the "FV plane" as the baseline of CT shaft position, and its vertical plane as the baseline of CT coronal position. It is benefit for us to diagnose and find the variation of anatomy. CT scan is thought as the best way to observe the adjoining relation of the ethmoid and sphenoid sinus. Shaft scan may observe the forward- and lateral-sphenoid styles of the ethmoid and the adjoining relation between the optic canal and ethmoid and sphenoid sinus. Coronal position may look well anterior- sphenoid style, around canal styles of sphenoid and ethmoid. The combination of shaft position and coronal position CT scans can know the relation of sphenoid, ethmoid sinus and the optic canal. Thought the statistic analysis of the CT number and the measure ofcadaveric skulls, we can regard the CT number of the optic adjoin, depth and angle as the guidance of the nasal endoscopic operation so as to avoid injuring the adjoining tissues.
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