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The vagus nerve has the longest course of all the cranial nerves, extending from the head to the abdomen. It has a parasympathetic component that helps regulate functions such as heart rate, digestion, and respiratory rate. Additionally, it has a sensory component that relays information from various visceral organs and a motor component responsible for speech and swallowing.
The vagus nerve emerges as a series of rootlets in a groove between the olive and inferior cerebellar peduncle. It traverses the posterior cranial fossa and exits the skull through the jugular foramen. The superior sensory ganglion of the nerve is located in the jugular foramen.
The inferior ganglion of the vagus lies below the jugular foramen. Just below the inferior ganglion, the cranial root of the accessory nerve joins the vagus nerve to distribute along its pharyngeal and laryngeal branches. In the neck, the vagus lies in the carotid sheath with the internal jugular vein and common carotid arteries. The right vagus runs on the posterior surface of the esophagus, contributing to the esophageal plexus. It enters the abdomen through the esophageal opening in the diaphragm, supplying the stomach, duodenum, liver, kidneys, small and large intestines up to the proximal two-thirds of the transverse colon. It has a wide distribution in the abdomen via the celiac, superior mesenteric, and renal plexuses. The left vagus runs anterior to the esophageal plexus, then enters the abdomen, supplying the stomach, liver, duodenum, and head of the pancreas.
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Introduction
0:06
What’s up, Taim Talks Med here. Let’s continue our Cranial nerve series. Cranial nerves are twelve pairs of nerves that exit the brain and the brainstem, and
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in this segment, we’ll talk detailed about the tenth cranial nerve, the vagus nerve. And we’ll do that by first drawing a quick scheme of the vagus nerve pathway.
0:25
Then we’ll break down the functional components of this nerve along with its respective nuclei in the medulla.
0:31
We’ll go through both the intracranial and the extracranial course, and then go through the branches of the vagus nerve, and to make it easier we’ll divide them according to
0:41
the anatomical region along its pathway, which are the jugular foramen, neck, thorax and
0:48
the abdomen. Alright, let’s start making a little scheme and then we’ll talk about it in detail. Now, the vagus nerve has the longest course of all the cranial nerves, extending from
Vagus Nerve Scheme
0:59
the head to the abdomen. It has a parasympathetic component, which help regulate functions like the heart rate,
1:06
digestion, and respiratory rate. It has sensory component to relay information from various visceral organs, and a motor
1:14
component for tasks like speech and swallowing. This nerve has altogether 4 nuclei that are located whithin the medulla oblongata.
1:25
We got a nucleus ambiguous which is a motor nucleus. Posterior, or dorsal nucleus of the vagus nerve, which is parasympathetic, nucleus of
1:35
solitary tract which is functionally divided into a viscerosensory part and a gustatory
1:41
part for taste. And we got the spinal nucleus of the trigeminal nerve which is somatosensory.
1:48
Now what happens it, nerves are going to go in and out through the medulla, on the lateral
1:53
aspect of the olive, called the retroolivary groove. So It has a motor component, parasympathetic component, and the sensory components.
2:03
Some important landmarks to put in here are the jugular foramen, superior ganglion of
2:09
the vagus nerve, and the inferior ganglion of the vagus nerve. And keep in mind the glossopharyngeal nerve also has a superior and an inferior ganglion
2:18
around the same area. These are different. Alright. The first branch that I wanna mention here is the auricular branch, which gathers sensations
2:28
from the skin of the anterior auricle, external acoustic meatus, and the external surface
2:33
of the tympanic membrane. The auricular branch will go through the mastoid canaliculus and then synapse with nuclei located
2:42
within the superior ganglion, and from here it’ll take sensory fibres directly to the
2:48
spinal nucleus of the trigeminal nerve. Another sensory nerve is the meningeal branch, which arises at the at the superior ganglion
2:57
and re-enters the skull via the jugular foramen to innervate the dura of the posterior cranial
3:04
fossa. Also taking sensory information towards the spinal nucleus of the trigeminal nerve.
3:11
Now, from here we’re going to do a couple of branches together since most branches of
3:16
the vagus nerve consists of a combination of parasympathetic, motor and sensory innervations.
3:23
So the motor component coming from the nucleus ambiguous will go through the jugular foramen
3:30
and the ganglia without synapsing with them. Then it’s going to take a turn towards the pharynx to contribute to the pharyngeal plexus,
3:38
together with the glossopharyngeal and the laryngopharyngeal nerves. So the vagus nerve here represents the motor component of the pharyngeal plexus and ultimately
3:49
provides motor innervation to most of the muscles of the soft palate (all but the tensor
3:54
veli palatini muscle), and of the pharynx (all but the stylopharyngeus muscle).
4:01
Around at the level of the inferior ganglion, the cranial component of the 11th cranial
4:06
nerve, the accessory nerve, is going to supply motor fibers into the vagus nerve, and further
4:13
towards the pharyngeal plexus. Which means that the 11th cranial nerve is going to help the vagus nerve innervate most
4:20
pharyngeal and soft palate muscles, both coming from parts of the nucleus ambiguous in the
4:26
brainstem. Some sources say the accessory nerve helps with this innervation and some sources mention
4:33
the vagus nerve alone does the job. So keep this in mind. Now, together with the pharyngeal branch, there are going to be sensory taste fibres,
4:43
sensing taste at around the region of the epiglottic valleculae, which are going to synapse with nuclei whithin the inferior ganglion, to further send information towards the nuclei
4:55
of the solitary tract. So the pharyngeal branch contain sensory visceral efferent fibers which are motor, and special visceral afferent fibers, for taste. Alright. The motor fibers are going to continue and give off fibers forming the superior laryngeal
5:03
nerve. The superior laryngeal nerve is also going to contain general visceral afferent fibers
5:10
that synapse with nuclei in the inferior ganglion, which goes towards the nuclei of the solitary
5:16
tract. The pharyngeal nerve is now going to split into an external branch and an internal branch.
5:23
The external branch is primarily going to innervate the cricothyroid muscle, which is
5:29
a muscle that aid in phonation, or vocalization. The internal fibers are going to contain a little bit of parasympathetic fibers aswell
5:38
coming in from the posterior nucleus of the vagus nerve. And they’re going to provide sensory innervation to the laryngeal mucosa above the vocal cords,
5:48
epiglottis and the root of the tongue, and parasympathetic innervation to glands and
5:53
vasculature in the same area. Further down the line we got the recurrent laryngeal nerve, which leaves the nerve at
6:01
the region of the neck, goes down to the thorax to loop around the subclavian artery on the
6:07
right side, and the aortic arch on the left side, and then they travel back up along the
6:13
neck. On its way, it’s going to give off branches to the trachea, and again providing parasympathetic
6:19
fibers aswell, innervating the mucosal lining of the trachea and mucosal glands and smooth
6:25
muscles in the same area. We have esophageal branches, which provide motor innervation to striated muscles of the
6:33
esophagus, sensory innervation to the mucosa and parasympathetic innervation to the glands
6:39
and smooth muscle of the esophagus. It’s also going to provide motor innervation to the inferior pharyngeal constrictor muscle,
6:47
and a little bit of sensory innervation to the pharyngeal area aswell. The recurrent laryngeal nerves are then going to go up towards the larynx and terminate
6:57
as the inferior laryngeal nerve. The inferior laryngeal nerve has a sensory component innervating the laryngeal mucosa
7:06
below the vocal cords, and a motor component innervating the intrinsic muscles of the larynx,
7:12
except the cricothyroid. As the inferior laryngeal nerve ascends, it’s going to form some synapsing fibres with the
7:21
internal branch of the superior laryngeal nerve. Alright. At this point the rest of the fibers are going to be general visceral afferent and efferent
7:32
fibers going together to various organs, so parasympathetic and sensory fibres go together.
7:40
Around the heart, there’s gonna be a cardiac plexus, which is a mixed plexus containing
7:45
parasympathetic fibers from the vagus nerve and sympathetic fibers from the sympathetic
7:51
trunk. The parasympathetic, as well as some sensory innervations from the vagus nerve come in
7:57
as the superior cervical, inferior cervical and thoracic cardiac branches.
8:03
While I did say that the nucleus ambiguous is a motor nucleus, research have shown that
8:10
most parasympathetic fibers coming in to the heart actually comes from the nucleus ambiguous,
8:16
and to lesser extent the posterior nucleus of vagus nerve, so even tho I’ve put it
8:21
here as though they come from the posterior nucleus of the vagus nerve, just keep in mind that most parasympathetic innervation to the heart come from the nucleus ambiguous, to
8:32
reduce its heart rate. Some variations also say that cardiac branches come from the recurrent laryngeal nerve and
8:39
not from the vagus nerve directly. I’m just basing this scheme off of how I learned it, but you know, keep these things
8:45
in mind. Now, there’s also going to be fibers forming the pulmonary plexus, called bronchial branches,
8:52
which innervates the bronchial tree and the visceral pleura. These again are parasympathetic fibers from the posterior nucleus, and sensory fibers
9:01
to the nuclei of solitary tract. Now, the vagus nerve is going to continue down the esophagus and form the esophageal
9:10
plexus, and then penetrate the diaphragm through the esophageal hiatus, and then divide into
9:16
two trunks. The left vagus nerve will form the anterior vagal trunk, and the right vagus nerve will
9:23
become the posterior vagal trunk. And this is important because they innervate different structures.
9:29
The anterior vagal trunk will give off the anterior gastric branches for the stomach,
9:35
and the hepatic branches for the liver and the lesser omentum. The posterior vagal trunk will give off the posterior gastric branches, which form the
9:45
gastric plexus together with the anterior gastric branches. And it’s going to give off the celiac branches, which feed into the celiac plexus, also known
9:55
as the solar plexus. The celiac plexus is a huge plexus within the abdominal cavity that forms secondary
10:03
plexuses that supply nearly all the abdominal organs. So, the parasympathetic input of the celiac plexus comes from the vagus nerve, that mainly
10:13
innervate organs in the upper abdomen. The sympathetic input comes from the splanchnic nerves.
10:19
The posterior vagal trunk is also going to give off a few fibres towards the liver to
10:25
innervate the liver and gallbladder, and a few fibres towards the kidneys. So that is the general scheme of the vagus nerve.
10:33
It’s just schematic, not exactly anatomically correct, but I tried to simplify it as much as I could to make it easier to study.
10:40
And again please keep in mind there are variations according to what source you study from. But we’ll use this to go through this nerve in detail.
Functional Components
10:48
So, before we go into the actual course and branches, I wanna quickly go through the functional
10:54
components of the vagus nerve, because understanding this will help you gain a better picture of
10:59
the vagus nerve. So, we consider the vagus nerve as a mixed nerve, meaning it consists of a motor component,
11:07
a sensory component and a parasympathetic component. The motor component of this nerve supply most muscles of the pharynx, laryngx, and some
11:16
muscles of the soft palate and the tongue. The parasympathetic component simulates smooth muscle and glands of the pharynx, larynx,
11:25
thoracic and abdominal organs. The sensory component is further subdivided into visceral and somatic, and visceral is
11:33
again subdivided into general and special visceral sensory fibers.
11:38
General visceral fibers bring sensations from the pharynx, larynx, trachea, oesophagus,
11:44
and the abdominal and thoracic viscera, and for the most parts travel with the parasympathetic component.
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Special visceral sensory fibers bring information about taste from epiglottis and posteriormost
11:56
part of tongue. And the somatic general sensory fibres will bring sensation from the outer ear and the
12:03
tympanic membrane. Alright so how does it look like. Special Visceral Efferent fibres which are motor fibres, come from nucleus ambiguous,
12:14
and innervate skeletal muscles of the pharynx and larynx, as well as muscles of the soft palate except tensor veli palatini, and parts of the muscles of the tongue.
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General Visceral Efferent fibers, or GVE fibers, are the parasympathetic component innervating
12:31
organs in the neck, thorax and the abdomen. This is one of the largest component of the vagus nerve, and it primarily comes from the
12:39
posterior nucleus of the vagus nerve, but I wrote here that some parts come from nucleus
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ambiguous because research show that some parasympathetic innervation to the hear actually comes from nucleus ambiguous.
12:51
The rest come from the posterior nucleus of the vagus nerve. Then we got General Visceral Afferent fibers, or GVA fibers.
13:00
Which bring visceral information such as distention of organs from the pharynx, larynx, trachea,
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esophagus, abdominal and thoracic viscera towards the inferior ganglion of the vagus nerve, and then towards the nucleus of the solitary tract.
13:16
Most of these fibers go together with the GVE fibers. Then we have Special visceral afferent fibers, or SVA fibers, taking in taste information
13:27
from the area around the epiglottis towards the inferior ganglion, and then towards the
13:33
nucleus of the solitary tract as well. Then we also have general somatic afferent fibers, which take in sensations primarily
13:40
from the skin of the ear towards the superior ganglion of the vagus nerve, and then towards
13:45
the spinal nucleus of the trigeminal nerve. Also bringing a little bit of information from the dura mater as well.
13:51
So this is what we’re going to work with. Let’s start with going through the nuclei again, and then do the course, and finish
13:58
up with going through the branches in a little more detail. This nerve is really not that complicated as it seems, don’t worry we’ll go through
Nuclei of Vagus Nerve
14:06
it step by step. And at the end I’ll show you the scheme again which’ll make more sense once you
14:11
go through this nerve. I know I say this a lot in my previous videos, but here again you see the spinal cord, the
14:19
medulla oblongata, cerebellum, Pons, Mesencephalon, and the Diencephalon. If we now focus on the lateral aspect of the brainstem, you’ll see this.
14:29
So again we got the nucleus ambiguous, giving off the special visceral efferent fibres, so motor fibres.
14:36
There are the nuclei of the solitary tract receiving both general visceral afferent fibres
14:41
from the pharynx, larynx, trachea, oesophagus, and abdominal and thoracic viscera, as well
14:46
as special visceral afferent fibres for taste sensations from the posterior most part of
14:52
the tongue and the epiglottis. We got the posterior nucleus of the vagus nerve, giving off a huge amount of parasympathetic
15:01
fibers towards the pharynx, larynx, thoracic and abdominal organs, called general visceral
15:06
efferent fibers. And we got general somatic afferent fibers coming in from skin around the external ear,
15:14
as well as general sensations from the dura mater, towards the spinal nucleus of the trigeminal nucleus.
15:20
They’re all going to go out from the medulla oblongata from the posterolateral part of
15:25
the medullary olive. A little bit inferior to the glossopharyngeal nerve.
Intracranial Course
15:30
From here, we can divide its course into intracranial course, and extracranial course, and the dividing
15:36
line between them would be the jugular foramen, from where this nerve exits the cranium. There’s really not much to talk about when it comes to the intracranial course luckily,
15:46
since it doesn’t branch off at this point. All it does it emerge from the medulla as series of rootlets.
15:53
It then goes along the cranial fossa and exits through the jugular foramen. So let’s do the extracranial course.
Extracranial Course
16:01
Just as the vagus nerve enters the jugular foramen, you’ll find two sensory ganglia.
16:07
They contain only sensory nuclei. There’s the superior ganglion of the vagus nerve which is located within the jugular
16:14
foramen, and the inferior ganglion of vagus which lies just below the jugular foramen.
16:21
At the region of the inferior ganglion, there’re gonna be motor fibers from the cranial root
16:26
of accessory nerve that joins the vagus nerve to be distributed along its pharyngeal and laryngeal branches.
16:33
In the neck, the vagus lies in the carotid sheath along with the internal jugular vein
16:38
and common carotid arteries. Then it descends. The right and the left vagus nerve descend a little bit differently, and it’s really
16:46
important to know this. What happens is, the right vagus nerve moves so it becomes posterior to the oesophagus,
16:54
while the left vagus nerve moves so it becomes anterior to the oesophagus.
17:00
They both then form the esophageal plexus. They’ll then follow the oesophagus through the diaphragm via the oesophageal hiatus.
17:09
Now what happens, is that the left vagus nerve will become the anterior vagal trunk running
17:15
anterior to the stomach, while the right vagus nerve becomes the posterior vagal trunk, running
17:21
on the posterior aspect of the stomach. This is important because the left and right vagal trunks give off different branches and
17:29
supply different regions in the abdominal cavity. So, this is the course. This is how this nerve actually travels within the body.
Branches of the Vagus Nerve
17:37
Now what I wanna do, is divide the branches of the vagus nerve into the branches in the jugular fossa, branches in the neck, branches in the thorax, and branches in the abdomen.
17:48
It makes so much more sense to divide them this way. Let’s do the branches in the jugular fossa first.
Branches in the Jugular Fossa
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The first branch that I wanna mention here is the meningeal branch. The meningeal branch arises at the at the superior ganglion and re-enters the skull
18:04
at the jugular foramen as you see here. This branch contains general somatic afferent fibres and supplies the dura of the posterior
18:13
cranial fossa. Then we got another nerve that also arises from the superior ganglion, called the auricular
18:20
branch. It’s going to re-enter the lateral portion of the jugular foramen via the mastoid canaliculus.
18:27
It runs through the temporal bone, passing close to the facial canal, reaching the surface
18:33
at the tympanomastoid fissure, just anterior to the external acoustic meatus.
18:38
It also contains general somatic afferent fibers and have their cell bodies located
18:45
in the superior ganglion. It innervates and supplies sensation to the external tympanic membrane, external acoustic
18:52
meatus, and a small portion of the external ear. So those are the two branches at the level of the jugular fossa.
Branches in the Neck
19:00
Let’s do the branches in the neck. The first one is the pharyngeal branch that arise from the inferior ganglion of the vagus
19:08
nerve and contain a mixture of visceral afferent fibers and motor fibers.
19:14
Notice here how the cranial part of the accessory nerve enter into the vagus nerve, fibers from
19:20
the accessory nerve is going to run together with the pharyngeal branch to supply with motor fibers aswell.
19:26
The pharyngeal branch of the vagus nerve is going to help form the pharyngeal plexus.
19:31
So the pharyngeal plexus contain a motor component derived from the vagus nerve, a sensory component
19:39
derived from the glossopharyngeal nerve, and sympathetic component derived from the laryngopharyngeal
19:44
nerve of the superior cervical ganglion. So motor component come from the vagus nerve, and they innervate all the muscles of the
19:53
pharynx, except the stylopharyngeus muscle which is innervated by the glossopharyngeal.
20:00
And it innervates all the muscles of the palate, except tensor veli palatini muscle, which
20:05
is innervated by the mandibular nerve. The pharyngeal branch also contains special visceral afferent fibers that is primarily
20:13
responsible for taste sensation from the few taste receptors in the epiglottis and surrounding
20:20
tissues. Then the superior laryngeal nerve. Consists of parasympathetic GVE fibers, sensory GVA fibers, and motor SVE fibers.
20:32
The superior laryngeal nerve will also originate from the inferior ganglion, and then run inferiorly,
20:39
on the lateral surface of the pharynx, then it splits into the internal branch and the
20:45
external branch. The internal branch of the superior laryngeal nerve penetrates the thyrohyoid membrane to
20:52
enter the internal aspect of the larynx. While the external branch of the superior laryngeal nerve runs down the lateral surface
21:01
of the inferior pharyngeal constrictor muscle. Now, the internal branch contain GVA fibers, that provides sensory innervation to the laryngeal
21:11
mucosa above vocal cords, epiglottis and the root of tongue. It also contain GVE fibers, providing parasympathetic innervation to glands and vasculature of the
21:22
same area. The external branch however is purely motor.
21:27
So it contain SVE fibers that will go down and innervate primarily the cricothyroid muscles.,
21:34
which helps with phonation, or vocalization. It might also send some motor fibres to the inferior pharyngeal constrictor, but it’s
21:42
primarily going to innervate the cricothyroid muscle. All other intrinsic laryngeal muscles are innervated by the recurrent laryngeal nerve,
21:51
which is another branch of the vagus nerve. The recurrent laryngeal nerve is also a mixed nerve containing parasympathetic GVE fibres,
22:00
sensory GVA fibres, and motor SVE fibres. This nerve is a little weird because it loops around the large vessels and then go up again,
22:10
but the course of the right and left recurrent laryngeal nerves differ due to the vascular
22:16
asymmetry in the upper thorax. On the right side, the recurrent laryngeal nerve passes over the anterior surface of
22:24
the subclavian artery, then loops under the brachiocephalic artery and starts to ascend
22:30
in the groove between trachea and the esophagus. On the left side, the recurrent laryngeal nerve passes over the anterior surface of
22:39
the aortic arch, then loops under the arch, then ascends in the groove between the trachea
22:45
and esophagus on the left side. As the nerve ascends between the trachea and the esophagus, it gives off tracheal branches,
22:54
containing GVA and GVE fibers. So sensory fibers for the mucosal lining of the trachea, and parasympathetic motor innervation
23:02
for the mucosal glands and smooth muscle. It gives off esophageal branches, containing GVA, GVE and SVE fibers.
23:12
So motor innervation for the striated muscles of esophagus, its upper parts, sesnsory for
23:19
the mucosal lining of the esophagus, and parasympathetic motor innervation for the mucosal glands and
23:26
smooth muscle. Then a little upwardsw e can see pharyngeal branches, that’s primarily SVE motor fibers
23:35
for the inferior pharyngeal constrictor muscle. Then the recurrent laryngeal nerve will terminate as the inferior laryngeal nerve, which contain
23:45
sensory GVA fibers for the larygngeal mucosa below vocal cords, and motor SVE fibers, supplying
23:52
all the intrinsic muscles of the larynx except the cricothyroid muscle which is innervated
23:57
by the superior laryngeal nerve. So the inferior laryngeal nerve innervates the Lateral and the posterior cricoarytenoid.
24:06
Transverse and the oblique arytenoid. Thyro-arytenoid, and the Vocalis muscle.
24:12
As it ascends, there might be some branches of the inferior laryngeal nerve that go together
24:17
with the internal branches of the superior laryngeal nerve. Then we got another nerve, this nerve is going to go all the way down towards the heart,
24:27
called the superior cervical cardiac branches. Running on both sides as you see here.
24:33
They branch off the vagus nerve at the upper parts of the neck. They descend behind the subclavian artery to diverge into the deep part of the cardiac
24:42
plexus. Giving parasympathetic GVE fibers, and sensory GVA fibers.
24:49
So those were the main branches in the neck. The branches in the thorax will also send off fibers that innervate the cardiac plexus,
Branches in the Thorax
24:57
called thoracic cardiac branches, and the inferior cervical cardiac branches. Now, keep in mind there might be some variations here.
25:05
Some sources say the inferior cardiac nerve arises from the recurrent laryngeal nerve on the left side, and some say it comes from the main vagus nerve.
25:13
But essentially they’re both going to contain parasympathetic GVE and sensory GVA fibers.
25:22
So what happens is, nucleus solitarius receives the baroreceptor sensory input, while the
25:28
nucleus ambiguous, and dorsal motor nucleus to a lesser extent, are involved in the parasympathetic
25:34
output. So usually parasympathetic fibers come from the posterior nucleus of vagus nerve, but
25:41
when we talk about the cardiac plexus it’s usually coming from the nucleus ambiguous.
25:46
The nucleus ambiguus contains vagal efferent neurons that inhibit the heart rate.
25:52
When heart rate increases, baroreceptor afferents are activated and terminate in the nucleus
25:58
tractus solitarius in the medulla. These signals get carried by the afferent nerve branches of CN IX and CN X.
26:07
The cells of NTS send excitatory signals to the nucleus ambiguus, which then sends inhibitory
26:14
signals to the sinoatrial node via CN X to reduce the heart rate, providing tonic inhibition
26:21
of the heart rate to serve as a cardioprotective function. And what happens when the heart rate becomes too low?
26:28
This parasympathetic response is not activated, allowing the heart rate to rise.
26:33
This is generally how this works. Other nerves in this area are the bronchial nerves. We got some anterior bronchial nerves that contribute to the anterior pulmonary plexus
26:43
which innervates the bronchial tree and the visceral pleura. And we got some posterior bronchial branches, that are larger and more abundant than the
26:52
anterior ones, and they form the posterior pulmonary plexus, innervating the same structures
26:58
as the anterior one. So again it contain parasympathetic GVE and sensory GVA fibers.
27:06
So if you stimulate the vagus nerve, it’ll cause bronchoconstriction, mucus secretion
27:12
and bronchial vasodilation. Remember it’s a parasympathetic response.
27:17
The vagus nerve also help initiating the cough reflex aswell. As the vagus nerve descend, they form the oesophageal plexus, providing parasympathetic
27:27
motor innervation and sensory innervation to the esophagus. And notice how the right vagus nerve goes behind the esophagus, and the left vagus nerve
27:37
goes in front of it. We’ll stop here, keeping it simple and straight forward. Let’s do the abdominal branches.
Branches in the Abdomen
27:44
Now, as we said the left vagus nerve ends up in front of the esophagus and the right
27:50
one ends up posterior to the esophagus. As they descend, they’re going to go through the esophageal hiatus of the diaphragm and
27:59
end up in the abdominal cavity. And now the left vagus will become the ventral vagal trunk and the right vagus will become
28:07
the posterior vagal trunk, and they will provide preganglionic parasympathetic GVE fibers,
28:14
and sensory GVA fibers to the abdominal cavity through various autonomic plexuses to individual
28:21
organs, together with the vessels. So the way this goes is that the anterior vagal trunk passes along anterior surface
28:29
of the oesophagus to the anterior surface of the stomach, and then gives off two groups
28:35
of branches, mainly the anterior gastric branches and the hepatic branches.
28:40
The anterior gastric branches will help form the gastric plexus, together with the gastric
28:46
branches of the posterior vagal trunk. And the hepatic branches will supply the liver and lesser omentum, and help form the hepatic
28:55
plexus. Those are the main branches of the anterior vagal trunk.
29:01
On the other side, the right vagus nerve descends and becomes the posterior vagal trunk.
29:08
And the posterior vagal trunk is a monster. It gives off the posterior gastric branches to supply the gastric plexus.
29:16
And it gives off celiac branches. These celiac branches will go towards a plexus called the celiac plexus, or the solar plexus.
29:26
And via the celiac plexus, parasymphatic preganglionic fibres of the posterior vagal trunk run to
29:33
the most part of the organs of abdominal cavity, primarily to the upper parts of the abdomen.
29:38
It’s going to provide parasympathetic fibers to the Adrenal glands, Kidneys, Small intestine,
29:45
Pancreas, Spleen and even the 2/3 of the transverse colon, the rest getting innervation from the
29:51
parasympathetic branches of the sacral plexus. Other minor branches that might come off from the posterior vagal trunk are renal branches
30:00
and hepatic branches, but primarily when we talk about the posterior trunk, it’s the celiac branches and the posterior gastric we think about.
30:08
So those are the main branches coming off from this nerve. Alright. So that was everything I had for the vagus nerve.
Recap
30:15
Here again you see the scheme for the vagus nerve. It’s just schematic, not exactly anatomically correct but I hope it’ll help you gain a
30:23
good understanding of this nerve. So, we now covered the vagus nerve. The next video is going to be about the eleventh cranial nerve, the accessory nerve.
30:32
Thank you so much for watching another one of my videos. If you enjoyed, learned something from it, please remember to like, comment your favourite
30:39
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30:45
box. Have fun ya’ll.
30:54
Peace.
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