眶下裂和眶下沟横断面CT表现及其解剖基础研究

目的研究正常人眶下裂和眶下沟横断面CT表现及其解剖基础,避免将其误认为眶壁骨折。方法正常颅骨25个,肉眼观察眶下裂和眶下沟解剖形态。5个颅骨和20名正常人,眶横断面CT扫描,观察眶后外侧形态,15例辅以多平面重建和三维立体重建。结果在标本和正常人横断面上,眶后外侧面同时反映眶外侧壁和大部分眶下壁,其表现有:(1)单处缺裂,两侧对称或不对称;(2)双处缺裂,缺裂之间夹有片状小骨,小骨长轴与眶外侧壁平行一致;(3)类似双处缺裂,缺裂之间出现片状小骨,小骨呈锥状,长轴在前后方向上。大体标本和眼眶重建图像显示,上述三种情况分别对应的解剖基础是:(1)棒球杆样眶下裂;(2)V形眶下裂,即眶下裂分内外两支,内支位于蝶骨大翼下缘与下颌骨后缘间,外支位于蝶骨大翼下缘与颧骨之间,内外支间形成一向上开口的“V”字形;(3)深陷的眶下沟,伴有突出并向内倾斜的外侧壁。结论熟悉正常人眶下裂和眶下沟的横断面CT表现及其解剖学基础,可以避免将其误认为眶壁骨折。

Inferior orbital fissure and groove: axial CT findings and their anatomic variation

Objective To show imaging findings of inferior orbital fissure(IOF)and groove(IOG)on axial CT scans and to discover their anatomic variations,so as to avoid misdiagnosing them as orbital fracture.Methods25normal skull were used to investigate the configurations of IOF and IOG.Five skulls were performed axial CT scans.20normal orbital axial scans were studied as well.MPR and RT-3D recon-structions were used in this study.Results skulls scans and normal orbital images on axial CT showed three sorts of findings:(1)single bony dehiscence between lateral and inferior walls;(2)first type of dou-ble bony dehiscence between lateral and inferior walls,among the dehiscence interposing a small bone.The long axis of the small bone was parallel to orbital wall;(3)second type of double bony dehiscence between lateral and inferior walls,but the long axis of the small bone was in anteroposterior direction.Anatomy and variation of three sorts of CT findings were corresponded respectively to:(1)a baseball club-shaped IOF;(2)a"V"-shaped IOF,that is composed of both of lateral and internal ramus,lateral ramus situates between the zygoma and the lateral portion of greater wing of sphenoid,and internal ramus between the maxilla and the internal portion of greater wing of sphenoid,both rami intercross caudally and open upwards in a"V"-shaped configuration;(3)a deep IOG with a protuberant lateral wall.Con - clusion Familiarity of imaging features on the axial CT scans and understanding of their anatomy of IOF and IOG would be helpful for avoiding misdiagnosis of orbital fracture.