Gross Block 2 Manual Lecture #12

What is the CNS made up of? What is the PNS made up of?
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What is the CNS made up of? What is the PNS made up of?
The CNS is made up of the brain and spinal cord. The PNS is made up of spinal nerves.
Is the autonomic nervous system part of the CNS or PNS?
The autonomic nervous system is part of both the PNS and CNS. (it is solely a MOTOR/efferent system)
What are the divisions of the autonomic nervous system? What is the difference between the two divisions?
The divisions are the sympathetic and parasympathetic nervous system. The sympathetic system REQUIRES body energy and is useful in emergency situations, whereas the parasympathetic system CONSERVES body energy and is utilized in the maintenance of homeostasis.
Despite being antagonistic, what 2 similarities do the parasympathetic and sympathetic nervous systems share?
1. Embryonic origin is from neural crest cells (NCC)
2. Both function via a two-neuron pathway comprised of a preganglionic neuoron in the CNS, and a postganglionic neuron in the PNS.
Which division of the autonomic nervous system is more complex? Why?
The sympathetic division is more complex than the parasympathetic. Because it is responsible for innervation of BV's, sweat glands, and arrector pili around the whole body. The parasympathetic is responsible only for visceral organs.
What are the somatic sensory (afferent) components of spinal nerves responsible for? What are the somatic motor (efferent) components responsible for?
The somatic sensory fibers are responsible for proprioception/temperature/pain/touch from the BODY. The somatic motor fibers innervate the skeletal muscles of the body (voluntary).
What are the visceral sensory (afferent) components of the spinal nerves responsible for? What are the visceral motor (efferent) components responsible for?
The visceral sensory fibers are responsible for pain/pressure from visceral organs (loosely). The visceral motor fibers are the distributed to the hair follicles, BV's, and sweat glands.
Which important fibers do the visceral motor components comprise?
The post-ganglionic sympathetic fibers. (These are all autonomic fibers and efferent fibers)
What are the other two types of autonomic fibers found in the spinal nerve, apart from the post-ganglionic sympathetic fibers?
The pre-ganglionic sympathetic fibers and the pre-ganglionic parasympathetic fibers.
What is the destination of the pre-ganglionic SYMPATHETIC fibers? What is the destination of the pre-ganglionic PARASYMPATHETIC fibers?
The pre-ganglionic sympathetic fibers travel in the ventral root of the spinal nerve before entering the sympathetic trunk through white rami communicantes. The pre-ganglionic parasympathetic fibers leave the spinal nerve as pelvic splanchnic nerves.
What is another name for the sympathetic portion of the autonomic nervous system?The thoracolumbar portion (because its ganglia are located in the thorax and upper lumbar regions of the vertebral column)What two types of neurons are involved in the sympathetic portion of the autonomic nervous system?preganglionic neurons and post-ganglionic neuronsWhat is the only origination point from the spinal cord for the preganglionic sympathetic neurons?The lateral horn (aka. intermediolateral cell column) between T1 and L3.What are the two locations where the post ganglionic neurons can be found?The postganglionic neurons can be found in the sympathetic trunk or the prevertebral ganglia, one or the otherWhat is the sympathetic trunk?The sympathetic trunk is a paired chain of sympathetic ganglia that run vertically (paravertebral) along the vertebral column from the base of the skull to the coccyxHow many ganglia are associated with the sympathetic trunk? What is final ganglia in the coccygeal region called when the two trunks unite?22 ganglia (3 cervical, 11 thoracic, 4 lumbar, and 4 sacral) although this is variable. The sympathetic trunk terminates in the coccygeal region as the "ganglion impar".What is the difference in location between the PREvertebral ganglia and the PARAvertebral ganglia?The prevertebral ganglia lie in front of the vertebral column, on the surface of the aorta, and are named after the arteries that branch out. The paravertebral ganglia lie adjacent to the vertebral column.What are the 4 divisions of the prevertebral ganglia?The prevertebral ganglia is divided into the celiac, aorticorenal, superior mesenteric, and inferior mesenteric ganglia (C,A,S,I)Where does the sympathetic trunk receive its inputs from?The sympathetic trunk receives inputs from the white rami communicantes.What are white rami communicantes?White rami communicantes are a bundle of preganglionic fibers that leave the lateral horn and synapse inside the sympathetic trunk. There are 14 pairs total, and they are called "white" because they are myelinated. ALL preganglionic sympathetic fibers enter the sympathetic trunk through these WRC.Where does the sympathetic trunk receive its outputs from?The sympathetic trunk receives outputs from the gray rami communicantes, postganglionic sympathetic fibers, and preganglionic sympathetic fibers.How many pairs of white rami communicantes are there? How many pairs of gray rami communicantes are there?There are 14 pairs of white rami communicantes. There are 31 pairs of gray rami communicantes.What are gray rami communicantes?Gray rami communicantes are a bundle of postganglionic fibers which are distributed one per spinal nerve, and that supply sweat glands and BV's. They appear gray because they are not myelinated.Where do the postganglionic sympathetic fibers travel to? Where do the preganglionic sympathetic fibers travel to?The postganglionic sympathetic fibers travel to the thoracic organs, head, and neck. The preganglionic sympathetic fibers travel through the trunk, but instead of synapsing, they branch into the greater, lesser, least, and lumbar splanchnic nerves.What one function do the greater, lesser, least, and lumbar splanchnic nerves have in common?They all provide sympathetic innervation to the organs of the abdomen and pelvisWhat is the PREganglionic sympathetic neurotransmitter? What is the POSTganglionic sympathetic neurotransmitter? What is the exception to this?Preganglionic sympathetic neurotransmitter is acetylcholine. The post ganglionic sympathetic neurotransmitter is norepinephrine. The exception is the postganglionic neurotransmitter in sweat glands is acetylcholine instead of norepinephrine.In which ganglia does the greater splanchnic nerve synapse? What does it supply?The greater splanchnic nerve synapses in the celiac ganglia. It supplies the foregut.In which ganglia do the lesser and least splanchnic nerves synapse? What do they supply?The lesser and least splanchnic nerves synapse in the aorticorenal ganglia. They supply the kidney.Which ganglion do the collaterals from the celiac ganglion enter? What do they supply?Collaterals come from the celiac ganglion and enter the superior mesenteric ganglion. They supply the midgut.What is the superior mesenteric ganglion supplied by?The superior mesenteric ganglion receives no DIRECT contribution from any of the named splanchnic nerves. Collaterals from the celiac ganglion and some contribution from the greater and lesser splanchnic nerves reach it.In which ganglia do the lumbar splanchnic nerves synapse? What do they supply?The lumbar splanchnic nerves (L1-3) synapse in the inferior mesenteric ganglion. They supply the hindgut.Are the ganglia of the preganglionic fibers called "prevertebral" or "paravertebral"?The ganglia of preganglionic fibers are "prevertebral" because they are located anterior to the vertebral column (unlike the sympathetic trunk, which is paravertebral)Where are the postganglionic sympathetic fibers of the celiac, aorticorenal, superior mesenteric, and inferior mesenteric ganglia distributed?The postganglionic fibers are distributed to the abdominal organsWhat is another name for the parasympathetic portion of the autonomic nervous system?The craniosacral portion.Preganglionic parasympathetic fibers can be found in which cranial nerves? Which cranial nerve innervates the pupillary sphincter?CN 3, 7, 9, 10. The pupillary sphincter is innervated by CN 3, via "short ciliary nerves".Which glands are innervated by CN 7?The lacrimal, sublingual, and submandibular glands.Which nerve innervates the lacrimal gland? What is the path of innervation?CN 7. Preganglionic parasympathetic fibers travel in the greater superficial petrosal nerve (a branch of CN 7). This branch merges with others to form the nerve of the pterygoid canal, which synapses in the pterygopalatine ganglia. The postganglionic fibers then travel to the lacrimal gland.Which nerve innervates the parotid gland? What is the path of innervation?CN 9. Preganglionic parasympathetic fibers travel with the lesser superficial petrosal nerve and synapse in the otic ganglia. Postganglionic parasympathetic fibers then innervate the parotid gland.What is the name of the ganglia that parasympathetic fibers from CN 7 pass through to innervate the lacrimal gland? What ganglia do fibers of CN 9 pass through to innervate the parotid gland?CN7: pterygopalatin ganglia CN 9: otic gangliaWhat is the name of the nerve that parasympathetic fibers of CN 7 travel through to innervate the lacrimal gland? What nerve do fibers of CN 9 pass through to innervate the parotid gland?CN 7: greater superficial petrosal nerve CN 9: lesser superficial petrosal nerveWhich nerve plays an important role in innervating the thorax, abdomen, neck, and gut (colon)?CN 10, the vagus nerveWhere do terminal ganglia lie?Within the organ they innervate. (Preganglionic fibers will go all the way to the organ they innervate, synapse there, and then postganglionic fibers innervate the organ.)Do parasympathetic or sympathetic fibers play a role in peristalsis and glandular secretions within the GI tract?Parasympathetics (rest and digest). Everything to do with eating, hunger, or digestion will be the responsibility of the parasympathetic nervous system.Where do the SACRAL preganglionic parasympathetic fibers originate in the spinal cord?S2-S4What are the sacral portion of preganglionic parasympathetic fibers in animals called? What functions do they controlCalled "nervi erigens". They control reproductive organs, sexual response, peeing, and pooping.What are the sacral portion of the preganglionic parasympathetic fibers called in humans? Where do these fibers synapse.Pelvic splanchnic nerves. They synapse in the pelvic organ.In the parasympathetic system, which is longer, the preganglionic fiber or the postganglionic fibers? Why?The preganglionic fiber is much longer. This is because the ganglion is located near or inside the target organ, which makes the postganglionic fiber very short.What is the neurotransmitter for preganglionic and postganglionic parasympathetic fibers?AcetylcholineWhat sensation do visceral afferent fibers traveling with the sympathetic fibers carry? What sensation do visceral afferent fibers travelling with the parasympathetic system carry?1. pain (exclusively) 2. pressure or size changes in organsWhat is referred pain?Pain that is felt in an area other than the source. Often occurs when visceral afferents that sense pain "refer" it to somatic afferents that enter the spinal cord/have their cell bodies at the same dorsal root ganglia. (ex: stomach pain felt in epigastric region)