descending and sigmoid colon, the rectum, and all pelvic organs receive their
parasympathetic preganglionic input via the Pelvic
Splanchnic nerves. The pelvic splanchnic nerves spring from the anterior
rami of the second, third, and fourth sacral nerves shortly after their emergence
from the pelvic sacral foramina. The contribution from the third sacral nerve
is usually the largest.