the axons of the parasympathetic division originate from presynaptic nerves.
where do the axons of the parasympathetic division originate from?
presynaptic nerves
the parasympathetic aspect of the facial nerve controls secretion of the sublingual and submandibular salivary glands, the lacrimal gland, and the glands associated with the nasal cavity. the preganglionic fibers originate within the cns in the superior salivatory nucleus and leave as the intermediate nerve (which some consider a separate cranial nerve altogether) to connect with the facial nerve just distal (further out) to it surfacing the central nervous system. just after the facial nerve geniculate ganglion (general sensory ganglion) in the temporal bone, the facial nerve gives off two separate parasympathetic nerves. the first is the greater petrosal nerve and the second is the chorda tympani. the greater petrosal nerve travels through the middle ear and eventually combines with the deep petrosal nerve (sympathetic fibers) to form the nerve of the pterygoid canal. the parasympathetic fibers of the nerve of the pterygoid canal synapse at the pterygopalatine ganglion, which is closely associated with the maxillary division of the trigeminal nerve (cn v). the postganglionic parasympathetic fibers leave the pterygopalatine ganglion in several directions. one division leaves on the zygomatic division of cn v and travels on a communicating branch to unite with the lacrimal nerve (branch of the ophthalmic nerve of cn v) before synapsing at the lacrimal gland. these parasympathetic to the lacrimal gland control tear production.
parasympathetic nervous system
sympathetic and parasympathetic divisions typically function in opposition to each other. but this opposition is better termed complementary in nature rather than antagonistic. for an analogy, one may think of the sympathetic division as the accelerator and the parasympathetic division as the brake. the sympathetic division typically functions in actions requiring quick responses. the parasympathetic division functions with actions that do not require immediate reaction. the sympathetic system is often considered the "fight or flight" system, while the parasympathetic system is often considered the "rest and digest" or "feed and breed" system.
autonomic nervous system