In addition the vagus is believed to contain secretory fibers to the stomach and pancreas. It probably contains many other efferent fibers than those enumerated above. Sympathetic Afferent Fibers of the Vagus, whose cells of origin lie in the jugular ganglion or the ganglion nodosum, probably terminate in the dorsal nucleus of the medulla oblongata or according to some authors in the nucleus of the tractus solitarius. Peripherally the fibers are supposed to be distributed to the various organs supplied by the sympathetic efferent fibers. These small medullated preganglionic fibers are collected together in the pelvis into the nervus erigentes or pelvic nerve which proceeds to the hypogastric or pelvic plexuses from which postganglionic fibers are distributed to the pelvic viscera.
Motor fibers pass to the smooth muscle of the descending colon, rectum, anus and bladder.
Vasodilators are distributed to these organs and to the external genitalia, while inhibitory fibers probably pass to the smooth muscles of the external genitalia. Afferent sympathetic fibers conduct impulses from the pelvic viscera to the second, third and fourth sacral nerves. Their cells of origin lie in the spinal ganglia. These preganglionic fibers enter the white rami communicantes and proceed to the sympathetic trunk where many of them end in its ganglia, others pass to the prevertebral plexuses and terminate in its collateral ganglia. The postganglionic fibers have a wide distribution.