Abstract: Objective To investigate the spatial relationship between adult acusticus externus and the pineal gland,cornu frontale ventriculi lateralis by using the mathematical methods of coordinate transformation.Methods The original 3-dimensional coordinate data of 30 patients were obtained on thinner CT scan from CT workstation,including meatus acusticus externus,angulus oculi lateralis,the pineal gland,cornu frontale ventriculi lateralis.Then,the original cordinate values were transformed to those in the new cordinate system (line between angulus oculi lateralis and meatus acusticus externus,meatus acusticus externus as origin,OM line and contralaterally meatus acusticus externus as flat)and statistics data were processed. Results The values of the pineal gland on X,Y,Z axis and cornu frontale ventriculi lateralis on X axis had significant difference between male and female(P<0.01).The values of cornu frontale ventriculi lateralis on Y,Z axis had no significant difference between male and female(P>0.05). Conclusion In this new cordinate system,the pineal gland and cornu frontale ventriculi lateralis in male and female adults had relatively stable spatial values,and had significant difference on OM line,which can be reference for operations.

Key words: pineal gland, lateral ventricles, ear, external