Human Anatomy and Physiology - N. I. Fedyukovich 2003

Nervous system
Autonomic nervous system
Parasympathetic division of the autonomic nervous system

The parasympathetic division of the Autonomic Nervous system is divided into cranial and sacral parts. The cranial part includes the autonomic nuclei and parasympathetic fibers of the oculomotor (III pair), facial (VII pair), glossopharyngeal (IX pair), and vagus (X pair) nerves, as well as the ciliary, pterygopalatine, submandibular, sublingual, and otic ganglia with their branches. In the Midbrain, adjacent to the motor Nucleus of the Oculomotor nerve, lies the accessory oculomotor nucleus (Yakubovich's nucleus). Axons of these Cells (preganglionic fibers) travel within the III pair of Cranial Nerves into the Orbit, and then reach the ciliary ganglion via the oculomotor ROOT, where they synapse on its cells. Postganglionic fibers (axons of the ciliary ganglion Neurons) travel within the ciliary nerves to the Eyeball and innervate the sphincter pupillae Muscle and the ciliary muscle. Parasympathetic preganglionic fibers traveling within the Facial Nerve originate in the superior salivatory nucleus, whose axons form the intermediate nerve and pass along with the facial nerve through the facial canal. Then, as the greater petrosal nerve, the parasympathetic fibers exit the facial canal, pass through the foramen lacerum at the Base of the Skull, and enter the pterygoid canal. Here, the greater petrosal nerve joins the sympathetic deep petrosal nerve to form the nerve of the pterygoid canal. Upon exiting the canal, the latter reaches the pterygopalatine ganglion, where the preganglionic parasympathetic fibers synapse.

Axons of the pterygopalatine ganglion cells (postganglionic fibers) travel within the corresponding nerves to innervate the mucous Glands of the Nasal cavity, ethmoidal and sphenoidal sinuses, soft and hard palate, and the lacrimal gland. Another part of the preganglionic parasympathetic fibers of the intermediate nerve travels within the chorda tympani to the lingual nerve, and along with it, proceeds to the submandibular and sublingual ganglia, where they synapse. Postganglionic fibers from these ganglia run to the Cytology/practical/98.html">Submandibular salivary gland to provide its secretomotor innervation.

The parasympathetic pathway of the Glossopharyngeal nerve is formed by the inferior salivatory nucleus, the otic ganglion, and the processes of their respective cells. Axons of the Cells of the inferior salivatory nucleus, located in the Medulla Oblongata, exit the cranial cavity through the jugular foramen within the glossopharyngeal nerve. Preganglionic parasympathetic fibers branch off as the tympanic nerve, which enters the tympanic cavity to form the tympanic plexus; these fibers then continue as the lesser petrosal nerve to reach the otic ganglion, where they synapse. Postganglionic fibers (axons of the otic ganglion cells) run to the Parotid salivary gland, providing its secretomotor innervation via the parotid Branches of the auriculotemporal nerve.

Parasympathetic fibers of the Vagus nerve arise from the posterior (parasympathetic) nucleus of the vagus nerve and numerous ganglia that are part of visceral Autonomic plexuses, as well as from the processes of cells located in this nucleus and these ganglia. Axons of the cells of the posterior nucleus of the vagus nerve, located in the medulla oblongata, travel within the branches of the vagus nerve. They reach the parasympathetic ganglia of the autonomic plexuses (periorgan and intraorgan). These parasympathetic ganglia are part of the cardiac, esophageal, enteric, and other visceral autonomic plexuses. The parasympathetic ganglia of these autonomic plexuses (periorgan and intraorgan) contain The Cell bodies of the second neuron of the efferent pathway, and their axons form bundles of postganglionic fibers that innervate the smooth muscle of the walls of Internal Organs and the glands of the viscera of the neck, Thorax, and abdomen.

The sacral part of the parasympathetic division of the autonomic nervous system is formed by the sacral parasympathetic nuclei located in the intermediolateral nucleus of the lateral horn of the Spinal Cord Gray matter at the level of the II—IV sacral segments. Axons of these nuclei cells (preganglionic fibers) join the Spinal Nerves via the anterior roots and, after exiting through the pelvic sacral foramina, branch out to form the pelvic splanchnic nerves. The latter run to the inferior hypogastric plexus and, within its branches, reach the Organs of the Urogenital System located in the pelvic cavity, as well as a part of the Large Intestine. Within or near the walls of these organs lie the rectal, prostatic, uterovaginal, vesical, and other plexuses which contain parasympathetic pelvic ganglia, where the preganglionic fibers of the pelvic splanchnic nerves synapse. Postganglionic parasympathetic fibers from the pelvic ganglia then proceed into the organs to provide parasympathetic innervation to smooth Muscles and glands.