王保仓　赵刚 

According to the nature of the sacral tumor, it could lead to the extrusion, invasion and destruction of the sacral nerve. S4 and S5 nerve were usually cut off, when S4 and S5 were fouled by sacral tumors. The tumor tissues of the benign sacral tumor in S3 and above were always scraped within the lesion, so that we should protect the nerve root to save the motion of lower limbs and urination function. The author’s experience: after keeping the nerve root of S1 and above, all the patients would be of the loss of urination function, and need to be catheterized in time. After keeping the nerve root of S3 and above, all patients could urinate. After keeping the nerve root of S2 and above, some of patients could urinate while others couldn’t. In this paper the anatomical function of the sacral nerve was introduced.