The parasympathetic part of the autonomic division of the PNS (Fig. 1.49) leaves cranial and sacral regions of the CNS in association with:
cranial nerves III, VII, IX, and X: III, VII, and IX carry parasympathetic fibers to structures within the head and neck only, whereas X (the vagus nerve) also innervates thoracic and most abdominal viscera; and
▪ spinal nerves S2 to S4: sacral parasympathetic fibers innervate inferior abdominal viscera, pelvic viscera, and the arteries associated with erectile tissues of the perineum.
Fig. 1.49: Parasympathetic Part of the Autonomic Division of the Peripheral Nervous System. Adapted from Drake, Mitchell & Vogl. Gray’s Anatomy for Students, 5th Ed. 2024. © Elsevier.
Like the visceral motor nerves of the sympathetic part, the visceral motor nerves of the parasympathetic part generally have two neurons in the pathway. The preganglionic neurons are in the CNS, and fibers leave in the cranial nerves.
