Microsurgical anatomy of the transcallosal-interforniceal approach to the third ventricle

Objective To supply microanatomic data for the application of the transcallosal-interforniceal approach, in order to help surgeons to identify and protect vital vascular and nervous structures during operation. Methods Fifteen adult cadaveric head specimens were dissected by using microsurgical anatomic skill, simulating the procedures of the transcallosal-interforniceal approach. Observation were performed on related anatomic structures, measurement and photographers were taken, too. Results A small artery was found in a groove located between the medial longitudinal striate in the middle of the corpus callosum; Using two points on the cortical surface as references that were located 5 and 7cm anterior to the central sulcus respectively, mean values of relative measurements were obtained as follows: ( 1 ) the distance between P5/P7 and the cingulate sulcus was 29.26mm and 30.43mm; (2) the distance between the lower margin of the corpus callosum and the fornix was 7. 53mm and 9. 88mm; (3) the height of the corpus callosum was 7. 18mm and 7.78mm; (4) the distance between the anterior commissure and the foramen of Monro was 5. 04mm, independent of P5 and P7. Conclusions The corridor of the transcallosal-interforniceal apporoach is bounded between the lines of P5-FM and P7-FM; The small artery in a groove located between the medial longitudinal striae should be used to landmark of incision into the corpus callosum; The quantitative inforation obtained in this study permitted preservation of important anatomic structures in operation, such as the motor strip, genu of the corpus callosum, fornical commissure and anterior commissure.