BACKGROUND: Researches are recently focus on topography and image dissection of nasolacrimal duct, but it is lack of systemically contrast researches between sectional anatomy and image anatomy on bone nasolacrimal duct by using dry cranium samples.OBJ ECTIVE: To investigate the characteristics of sectional anatomy and image anatomy on bone nasolacrimal duct and provide evidences for related operations of nasolacrimal duct.DESrGN: Self controlled study.SETTING: Office of Teaching Supplies, Chengdu Medical College.MATERIALS: The experiment was carried out in the Topography Laboratory, Department of Human Anatomy, Chengdu Medical College from September 2005 to September 2006. Non-injured dry cranium was randomly selected from 34 adults (68 sides), including 34 sides on males and 34 sides on females.METHODS: ① Based on OM line, a routine scanning base line, which was regarded as the axial scanning baseline,samples were scanned at flat level with SHIMADZU CT device. Bone nasolacrimal duct was factitiously divided into three parts, including 1/3 superior segment, 1/3 middle segment and 1/3 inferior segment. The means at each related layer were determined as the final results. ② Cranium samples were signed based on image scanning baseline, and then they were cut into sections at cross section fault along scanning baseline at flat level with section razor. In addition, related indexes of bone nasolacrimal duct were measured and compared with image results.MAIN OUTCOME MEASURES: ① Anterior, posterior, left and right diameters of superior aperture, 1/3 superior segment,1/3 middle segment, 1/3 inferior segment and inferior aperture of bone nasolacrimal duct; ② depth of internal bone wall and posterior bone wall in superior aperture, 1/3 superior segment, 1/3 middle segment, 1/3 inferior segment and inferior aperture if bone nasolacrimal duct; ③ position and form of inferior aperture of bone nasolacrimal duct; ④ comparisons of bone nasolacrimal duct between image anatomy and sectional anatomy.RESULTS: ① Anterior, posterior, left and right diameters of cross section of bone nasolacrimal duct: Superior aperture of bone nasolacrimal duct was narrow, but inferior aperture was changed obviously. Diameter was increased from top to bottom. In addition, anterior and posterior diameters were more than left and right ones. There was significant difference in internal diameter of superior aperture and 1/3 inferior segment of bone nasolacrimal duct between male and females (t =2.458, 2.227, P ＜ 0.05). However, there was no significant difference in internal diameter of 1/3 superior segment, 1/3 middle segment and inferior aperture of bone nasolacrimal duct between male and female (P ＞ 0.05). ② Depth of internal bone wall and posterior bone wall of bone nasolacrimal duct at cross section: Depths of internal bone wall and posterior bone wall of bone nasolacrimal duct were (0.87±0.23) mm and (0.21±0.19) mm, respectively. In addition, there was significant difference between them (t =2.547, P ＜ 0.05). However, there was no significant difference in depth of internal bone wall and related posterior bone wall of superior aperture, 1/3 superior segment, 1/3 middle segment, 1/3 inferior segment and inferior aperture of bone nasolacrimal duct between male and female (P ＞ 0.05). ③ Position and form of inferior aperture of bone nasolacrimal duct changed remarkably. Results of image anatomy of bone nasolacrimal duct were as the same as those of sectional anatomy.CONCLUSION: Perfection of normal sectional anatomy and image anatomy of bone nasolacrimal duct is beneficial for successfully performing related operations of nasolacrimal duct and reducing complications.