To expose the anterior surface of the prostate, it is necessary to displace the peritoneum superiorly. 在暴露前列腺的前面时，必须向上推开腹膜。
This boundary is like the outer circumference of the Escher print or the surface of the solid cylinder I considered earlier. 这个边界就类似艾雪版画的外缘或者前面提过的圆柱体的表面。
