Visceral Intro & Parasympathetics Flashcards
Typically, what NT is released by parasympathetic neurons? Sympathetic?
Parasympathetic = cholinergic Sympathetic = adrenergic
T/F: The visceral nervous system is concerned with the internal and external environments of the body.
False - Internal
What are some examples of structures innervated by the visceral nervous system (he lists 4)?
Vasculature
Secretory glands
Abdominopelvic Cavity
Thoracic Cavity
What is the location of Visceral afferent cell bodies?
Dorsal root ganglia or cranial nerve ganglion
Where do central processes enter the cord?
Through posterior root or specific cranial nerve
Where do peripheral processes carry impulses from?
Viscera to cell bodies via autonomic ganglia, plexus, or somatic nerves
T/F: There are no synapses in the PNS.
True
What structures do Sympathetic afferents travel through?
Sympathetic trunk to spinal ganglia (via anterior primary ramus & posterior rootlets).
Pass through white ramus communicans
What structures do Parasympathetic afferents travel through?
Sacral spinal nerves & cranial nerves
What are the associated receptors for visceral afferents (3)?
Pressure (baroreceptors) Chemical concentrations (CO2/O2 in blood) Muscle Stretching (GI tract)
Which CN carry preganglionic parasympathetic fibers? Which sacral spinal nerves?
III, VII, IX, X
S2-S4
Where do pre-ganglionic parasympathetic fibers synapse?
On post-ganglionic neurons in peripheral ganglia
Post-ganglionic parasympathetics extend to effector organs to assist in what functions (4)?
- Decrease CO (HR/SV)
- Constrict pupils
- Constrict bronchial tree
- Stimulate peristalsis
Which cranial nerves supply structures in the head?
III, VII, IX
Which nerves supply the distal parts of the digestive system & urogenital system?
S2, S3, S4
Which CN supplies respiratory, cardiac, and digestive structures in neck, thorax, and abdomen?
Vagus (X)
Where are pre-ganglionic cell bodies located for CN III?
Accessory oculomotor nucleus in the periaqueductal gray
Where do pre-ganglionic fibers of CN III synapse?
Ciliary ganglion
Which two muscles are supplied by the post-ganglionic axons of CN III? What nerves are they carried in?
Carried in short ciliary nerves where they enter the eyeball
Supply:
Ciliary Muscle: contraction makes lens more convex to focus on closer objects
Sphincter Pupillae: contraction decreases the size of the pupil
Where are pre-ganglionic cell bodies located for CN VII?
Superior salivary nucleus
How do pre-ganglionic fibers of CN VII exit the CNS?
Via the intermediate nerve, carried in Greater Petrosal nerve or Chorda Tympani
Where does the greater petrosal nerve leave the facial nerve? What type of fibers does it carry?
Geniculate Ganglion - pre-para fibers carried through hiatus for greater petrosal nerve
What is the path of the greater petrosal nerve after it exits via the greater petrosal hiatus?
Re-enters the petrous part of temporal bone via foramen lacerum
Travels in pterygoid canal to join Pterygopalatine ganglion
Where are post-ganglionic fibers distributed to (of the greater petrosal nerve)?
Distributed in lacrimal & pterygopalatine nerves to reach lacrimal, nasal, palatine, & pharyngeal glands
Describe the path of preganglionic parasympathetic fibers of the chorda tympani. Do it, lazy bones.
Carries fibers through tympanic cavity
Leaves temporal bone through the pterygopalatine fissure
Combines with lingual nerve (branch of V3)
Preganglionic fibers leave lingual nerve to reach submandibular ganglion
Where do postganglionic fibers travel to from the chorda tympani?
Submandibular & sublingual glands
ps glands in mucous membranes of oral cavity & lingual glands on ant. part of tongue also receive parasympathetic info from submandibular gland
Where are the preganglionic cell bodies located for the glossopharyngeal nerve?
Inferior salivary nucleus
What nerve carries preganglionic fibers for CN IX?
Tympanic nerve - carries fibers through tympanic canaliculus into tympanic cavity
What forms the tympanic plexus?
Postganglionic sympathetic fibers from the superior cervical ganglion
Which fibers pass through the tympanic plexus? What do they reform as?
Preganglionic parasympathetic
Reform as lesser petrosal nerve (to otic ganglion)
Which glands are supplied by postganglionic parasympathetic fibers from the otic ganglion?
Parotid gland (via auriculotemporal nerve) Posterior lingual glands (via lingual branch of CN IX)
Visceral afferents carried in the branch of the carotid sinus from baroreceptors in the carotid sinus and chemoreceptors in the carotid body are associated with which CN?
CN IX
Where are preganglionic cell bodies located for CN X?
Dorsal nucleus of the vagus
Where are postganglionic cells usually located for CN X (he lists 3)?
In the organs supplied or blood vessels that supply the organs
Myocardium
Submucosal plexus
Myenteric plexus
What nerves carry preganglionic fibers to supply the heart?
Superior & Inferior cardiac nerves (of CN X)
In the pathway to the heart, where do preganglionic fibers of CN X synapse?
Cardiac plexus at base & wall of heart
In the pathway to the heart, where are postganglionic fibers of CN X carried to (3 places)?
- Sinoatrial (SA) node
- Atrioventricular (AV) node
- AV bundle to reach subendocardial branches (Purkinje fibers)
How do parasympathetic impulses affect the heart?
Inhibit myocardium
Constrict coronary arteries
What nerves carry preganglionic fibers to supply the lungs?
Anterior & Posterior bronchial branches (of CN X)
In the pathway to the lungs, where do preganglionic fibers of CN X synapse?
Pulmonary plexuses surrounding bronchial tree
In the pathway to the lungs, where are postganglionic fibers of CN X carried to?
Bronchial musculature
Bronchial glands
What influences parasympathetic impulses in the lungs?
Constriction of bronchial tree & increased secretions of bronchial glands
E.g. Asthma Patients
In the pathway to the esophagus, what nerves carry preganglionic fibers?
Recurrent laryngeal nerves
Anterior/Posterior esophageal branches
In the pathway to the esophagus, where do preganglionic fibers of CN X synapse?
Wall of esophagus
In the pathway to the esophagus, what do postganglionic fibers supply?
Smooth muscle fibers of the esophagus
**Upper 1/3 of esophagus is skeletal muscle (recurrent laryngeal n. supply)
In the pathway to the stomach, what carries preganglionic fibers?
Branches from anterior (4) and posterior (6) vagal trunks
In the pathway to the stomach, where do preganglionic fibers of CN X synapse?
Submucosal (Meissner’s) & Myenteric (Auerbach’s) Plexuses in the stomach wall
In the pathway to the stomach, what do postganglionic axons supply?
Smooth muscle fibers from Meissner’s & Auerbach’s plexuses
What is the result of parasympathetic stimulation in the stomach?
Contraction of smooth muscle and secretion of gastric juices
Preganglionic fibers reach the SI, cecum, vermiform appendix, and ascending/transverse colon via which plexuses?
All are carried via Posterior Vagal Trunk
Duodenum via Celiac Plexus
Remainder via traveling through Celiac Plexus and Superior Mesenteric Plexus
True/False: Preganglionic fibers for the SI, cecum, vermiform appendix, and ascending/descending colon synapse in the submucosal & myenteric plexuses.
True! Same as stomach
**Postganglionic fibers reach smooth muscle fibers via the aforementioned plexuses
What is the result of parasympathetic stimulation in the SI, cecum, vermiform appendix, and ascending/transverse colon?
Contraction of smooth muscle & secretomotor for intestinal glands
What is an important feature of the vermiform appendix?
Nociceptors (visceral afferents)
Which preganglionic fibers reach the gall bladder, pancreas, and biliary tree?
Hepatic branch of the right vagal trunk via the hepatic plexus (extension of celiac plexus)
Where do synapses occur for the hepatic branch of the right vagal trunk?
Muscular walls of the gall bladder and biliary tree and in the glandular tissue of the pancreas
Postganglionic fibers supply which structures in the pathway to the gall bladder, pancreas, and biliary tree?
Smooth muscle fibers or glands of intended target
What is the result of parasympathetic stimulation to the gall bladder, pancreas, and biliary tree?
Increases smooth muscle activity in the gall bladder and biliary vessels. It is secretomotor for the pancreatic glands.
How do preganglionic fibers supply the spleen?
Via the posterior vagal trunk by way of the splenic plexus (extension of celiac plexus)
How do fibers reach the kidneys?
Through the renal plexus via the posterior vagus
T/F: The motor supply to the kidney is strictly sympathetic.
True
Parasympathetic fibers reaching the kidney are likely visceral afferents
Where do preganglionic fibers to the liver come from?
Primarily the anterior vagal trunk (though some come the posterior)
T/F: The parasympathetic supply to the liver is likely primarily efferent.
False - Afferent, like the kidney and the suprarenal glands
Which sacral nerves make up the sacral parasympathetic pathway?
S2, S3, S4
Where do S2-S4 arise? What are they carried in?
Arise in lateral horns of S2-4 cord levels, carried in Pelvic Splanchnic nerves
Descend in cauda equina
Where do the pelvic splanchnic nerves travel to?
Inferior hypogastric (pelvic) plexus, distributed to pelvic organs.
Rectum, internal genitalia, base of urinary bladder
How do sacral parasympathetic fibers reach the distal part of the digestive tract?
Through the inferior hypogastric plexus to the superior hypogastric and inferior mesenteric plexuses
What is the preganglionic pathway to the distal colon?
Travel through the inferior hypogastric plexus to reach the superior hypogastric and inferior mesenteric plexuses via the hypogastric nerve
**Postganglionic also reaches target form inferior mesenteric plexus
What makes up the distal colon?
Descending & sigmoid colon
What are the preganglionic and postganglionic pathways to the rectum & anus, and also the urinary bladder?
Pre- to inferior hypogastric plexus
Post - from inferior hypogastric plexus
The target in the urinary bladder is the detrusor muscle
What initiates emptying of the urinary bladder?
Parasympathetic stimulation
Somatic supply to external urethral sphincter follows a similar pathway, neurons inhibited as bladder empties
What is the preganglionic pathway for the prostate gland & seminal vesicle?
Fibers reach the prostatic plexus via inferior hypogastric plexus
What is the postganglionic pathway for the prostate gland and seminal vesicle?
Smooth muscles of the prostatic urethra & seminal vesicle
In the pathway to the uterus, the preganglionic fibers travel to the inferior hypogastric plexus. Describe their postganglionic distribution.
Distributed throughout the myometrium of the uterus
How does parasympathetic stimulation affect the uterus?
Most likely inhibits the muscles (hormonal factors may pay a larger role)
In the pathway to the vagina, where do preganglionic fibers synapse?
Vaginal plexus, which they reach via the inferior hypogastric plexus
How does parasympathetic stimulation affect the vagina?
Vasodilation and increased secretory activity at the target
Fibers reaching the inferior part of the vagina may rely on what nerve to reach the target?
Pudendal nerve
In the pathway to the penis or clitoris, where do preganglionic fibers synapse?
Travel to cavernous plexus via inferior hypogastric plexus
How does parasympathetic stimulation affect the penis/clitoris?
Vasodilation and the filling of the sinuses of erectile tissue.
