Preganglionic parasympathetic fibers leave the brain stem from inferior salivatory nucleus in the glossopharyngyeal nerve and then through its tympanic and then the lesser petrosal branch pass into the otic ganglion.

Preganglionic parasympathetic fibers originate from the glossopharyngeal nerve via the lesser petrosal nerve.

Preganglionic sympathetic neurons are in the spinal cord, at thoraco-lumbar levels.

Preganglionic oculomotor neurons within the Edinger – Westphal nucleus shall be referred to as the EWpg, and the neuropeptide-containing neurons shall be known as the centrally-projecting Edinger Westphal nucleus, or EWcp.

# REDIRECT Preganglionic nerve fibers

* Second-order neuron disorder: Preganglionic lesions ( e. g. compression of the sympathetic chain by a lung tumor ).

The parasympathetic division has craniosacral “ outflow ”, meaning that the neurons begin at the cranial nerves ( CN 3, CN7, CN 9, CN10 ) and sacral ( S2-S4 ) spinal cord.

Enteric neurons are also modulated by input from the CNS, from preganglionic neurons located, like parasympathetic ones, in the medulla oblongata ( in the dmnX ).

* Acetylcholine is the preganglionic neurotransmitter for both divisions of the ANS, as well as the postganglionic neurotransmitter of parasympathetic neurons.

In the parasympathetic system, ganglionic neurons use acetylcholine as a neurotransmitter, to stimulate muscarinic receptors.

As is true in the sympathetic nervous system, efferent parasympathetic nerve signals are carried from the central nervous system to their targets by a system of two neurons.

The axons of presynaptic parasympathetic neurons are usually long: They extend from the CNS into a ganglion that is either very close to or embedded in their target organ.

Cardiac neurons are uniquely subject to influence by the sympathetic and parasympathetic influence of the autonomic nervous system unlike skeletal muscle.

As well as motor neurons, the nucleus ambiguus in its " external formation " contains cholinergic preganglionic parasympathetic neurons for the heart.

* Onuf ’ s nucleus cells are anatomically linked with the sacral parasympathetic motor neurons and have many peptidergic nerve terminals.

Adie's pupil is caused by damage to peripheral pathways to the pupil ( parasympathetic neurons in the ciliary ganglion that cause pupillary constriction to bright light and with near vision ).

There is also some evidence for postsynaptic receptors on sympathetic neurons allowing the parasympathetic nervous system to inhibit sympathetic effects.

Visceromotor nerve axons ( which constitute a portion of cranial nerve III, along with the somatomotor portion derived from the Edinger-Westphal nucleus ) synapse on ciliary ganglion neurons, whose parasympathetic axons innervate the iris sphincter muscle, producing miosis.

Familial dysautonomia ( FD ), sometimes called Riley – Day syndrome and hereditary sensory and autonomic neuropathy type III ( HSAN-III ) — is a disorder of the autonomic nervous system which affects the development and survival of sensory, sympathetic and some parasympathetic neurons in the autonomic and sensory nervous system resulting in variable symptoms including: insensitivity to pain, inability to produce tears, poor growth, and labile blood pressure ( episodic hypertension and postural hypotension ).

The NTS indirectly modulates the activity of sympathetic and parasympathetic ( vagal ) neurons in the medulla and pons through the hypothalamus.

In the pterygopalatine ganglion, the preganglionic parasympathetic fibers from the greater petrosal branch of the facial nerve synapse with neurons whose postganglionic axons, vasodilator, and secretory fibers are distributed with the deep branches of the trigeminal nerve to the mucous membrane of the nose, soft palate, tonsils, uvula, roof of the mouth, upper lip and gums, and upper part of the pharynx.

Similarly, acetylcholine released from parasympathetic neurons may interact with muscarinic-2 and muscarinic-4 receptors to inhibit neurally released acetylcholine.

One possible cause of Harlequin syndrome is a lesion to the preganglionic or postganglionic cervical sympathetic fibers and parasympathetic neurons of the ciliary ganglion.

Important as these differences are, they should not obscure the basic fact that by shifting the hypothalamic balance sufficiently to the parasympathetic side, we produce depressions, whereas a shift in the opposite direction causes excitatory effects and, eventually, maniclike changes.

Pupil reaction to light is important because it shows an intact retina, and cranial nerve number 2 ( CN II ); if pupils are reactive to light, then that also indicates that the cranial nerve number 3 ( CN III ) ( or at least its parasympathetic fibers ) are intact.

# Autonomic nervous system transmission: both the sympathetic and parasympathetic nervous systems are regulated by GPCR pathways, responsible for control of many automatic functions of the body such as blood pressure, heart rate, and digestive processes

Atropine and scopalamine ( both of which are found in very high concentrations in datura ) are muscarinic antagonists which can be used to treat Parkinson's disease and motion sickness, and to inhibit parasympathetic stimulation of the urinary tract, respiratory tract, GI tract, heart and eye.

Other processes usually regulated by the body such as the immune system are also controlled indirectly through the sympathetic and parasympathetic nervous system.

One area of interest is the autonomic nervous system, which is composed of two components: the sympathetic nervous system controls arousal and physical activation ( i. e. the fight-or-flight response ) and the parasympathetic nervous system controls physical processes that are automatic ( e. g. saliva production ).

Some typical actions of the sympathetic and parasympathetic systems are listed below.

The parasympathetic nerves ( PSNS ) are autonomic ( aka " visceral ") branches of the peripheral nervous system ( PNS ).

The parasympathetic nerves that arise from the S2, S3, and S4 spinal nerves are commonly referred to as the pelvic splanchnic nerves or the " nervi erigentes ".

As a result, the postsynaptic parasympathetic nerve fibers are very short.

The afferent fibers of the autonomic nervous system, which transmit sensory information from the internal organs of the body back to the central nervous system, are not divided into parasympathetic and sympathetic fibers as the efferent fibers are.

Each recurrent laryngeal nerve supplies the trachea and the esophagus with parasympathetic secretomotor innervation for glands associated with them ( and other fibers that are not PSN ).

In truth, the functions of both the parasympathetic and sympathetic nervous systems are not so straightforward, but this is a useful rule of thumb.

Salivary glands are innervated, either directly or indirectly, by the parasympathetic and sympathetic arms of the autonomic nervous system.

The cell bodies for muscular efferent nerves are found in the facial motor nucleus whereas the cell bodies for the parasympathetic efferent nerves are found in the superior salivatory nucleus.

Pelvic splanchnic nerves are the primary source for parasympathetic innervation.

The autonomic nervous system also has two subdivisions, the sympathetic and the parasympathetic, which are important for regulating the body's basic internal organ functions such as heartbeat, breathing, digestion, etc.

It arises from cells in the nucleus ala cinerea, the parasympathetic nucleus of origin for the tenth cranial nerve ( vagus ), located in the medulla oblongata.