Origin and topography of the pelvic nerves in human embryos and fetuses.

The pelvic plexus is observed in human embryos at stage 15 and during the last two embryonic weeks the secondary plexuses are formed. The pelvic nerves are found at stage 15 and in embryos they arise from anterior rami of the sacral nerves S2-S4. In fetuses the pelvic nerves originate from the anterior rami S1-S5. Number of pelvic nerves from one anterior ramus varies from 1 to 3.