![]() The vagus innervation ends at the junction between the midgut and hindgut, just before the splenic flexure of the transverse colon. The vagus nerve does not participate in these cranial ganglia as most of its parasympathetic fibers are destined for a broad array of ganglia on or near thoracic viscera ( esophagus, trachea, heart, lungs) and abdominal viscera ( stomach, pancreas, liver, kidneys, small intestine, and about half of the large intestine).From these four ganglia the parasympathetic nerves complete their journey to target tissues via trigeminal branches ( ophthalmic nerve, maxillary nerve, mandibular nerve). Certain cranial nerves in the cranium, namely the preganglionic parasympathetic nerves (CN III, CN VII, CN IX and CN X) usually arise from specific nuclei in the central nervous system (CNS) and synapse at one of four parasympathetic ganglia: ciliary, pterygopalatine, otic, or submandibular. ![]() Parasympathetic nerve supply arises through three primary areas: The parasympathetic nerves are autonomic or visceral branches of the peripheral nervous system (PNS). Owing to its location, the parasympathetic system is commonly referred to as having "craniosacral outflow", which stands in contrast to the sympathetic nervous system, which is said to have "thoracolumbar outflow". Three spinal nerves in the sacrum (S2–4), commonly referred to as the pelvic splanchnic nerves, also act as parasympathetic nerves. Specific nerves include several cranial nerves, specifically the oculomotor nerve, facial nerve, glossopharyngeal nerve, and vagus nerve. Nerve fibres of the parasympathetic nervous system arise from the central nervous system. Its action is described as being complementary to that of the sympathetic nervous system, which is responsible for stimulating activities associated with the fight-or-flight response. The parasympathetic system is responsible for stimulation of "rest-and-digest" or "feed and breed" activities that occur when the body is at rest, especially after eating, including sexual arousal, salivation, lacrimation (tears), urination, digestion, and defecation. The autonomic nervous system is responsible for regulating the body's unconscious actions. The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes considered an independent system. The parasympathetic nervous system ( PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system.
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