Understanding the Pons in the CNS

What's up, Merete here! Let's continue the anatomy of the central nervous system. In this segment, we will cover the complete anatomy of the Pons. So remember, the central nervous system consists of two parts, the Encephalon and the spinal cord. The Encephalon is then further subdivided into specific parts. We have the brainstem, which consists of the medulla, pons and the midbrain, or the mesencephalon. We have the cerebellum back here, and the diencephalon and the tenencephalon. So our focus in this video is going to be ponds, which is here. So in this video, we're first going to cover the external surfaces of ponds, basically look at its topography and what structures you will find from an anterior view and a posterior view. And then we're going to slice up the ponds and look at the internal surface, basically see how the gray matter and the white matter are arranged within it. And then I made a little quiz at the end of this video, which might help you if you need to memorize. Alright, so we can start by replacing this picture with a little more realistic one. Pons is located here, lying above the medulla and in front of the cerebellum, and down here you can see the spinal cord. Now if you remove a part of the cerebral cortex, you'll be able to see the rest of the pons, as well as the mesencephalon, or the midbrain, which is the most superior part of the brainstem. Alright, now, externally, your pons have two surfaces, it has an anterior surface, and a posterior surface. Let's now cover the typical morphology of these two surfaces. Starting with the anterior surface first. And we'll do that by looking at the brainstem from this perspective. We'll see this. So again, Pons is this prominent bulb you see here. In the midline of the anterior surface, there's a sulcus called the basilar sulcus. Laterally on either side, you'll see that the Pons turns backwards towards the cerebellum. And that is because Pons forms the middle cerebellar peduncles on either side. which continue into the cerebellum back here. That was the general morphology of the anterior surface of Pons, but there are some cranial nerves that leave the brainstem at this area. We have 12 cranial nerves in our body, and each serves its particular function for our brain, but from the anterior part of Pons, you will see a nerve that goes out between the pyramids of the middle of the lingara and Pons. This nerve is the 6th cranial nerve, the nervus abducens, that goes to the lateral extraocular muscles of the eyes to help with abduction of the eyeballs. Then between the olives and the middle cerebellar peduncles, you will find the cranial nerve number 7, the facial nerve which provides motor innervation for the facial muscles that help with facial expressions, and the cranial nerve number 8, the vestibulocochlear nerve, for hearing imbalance. The last nerve is at the surface of the pons, and that is the fifth cranial nerve, the nervus trigemnus. It's a very large nerve that goes to your facial region to provide sensory innervation, motor innervation as well as parasympathetic innervation for the glands. So all of these nerves emerge from the anterior area of Pons. Now let's turn this model around and look at the posterior surface. From the posterior view, you will see that the cerebellum covers the whole posterior area of Pons. So let's go ahead and remove the cerebellum. So Pons is here, above the medulla and below the midbrain, or mesencephalon. Pons doesn't really have any specific structures on its own, rather it works with the medulla and mesencephalon in forming certain structures. One of them is the rhomboid fossa. The rhomboid fossa has many nuclei for the cranial nerves, and is a very important landmark for tracts and nuclei. I will cover this in detail in my next video, but for now, I wanted to know that the upper part of the rhomboid fossa is formed by pons, and the lower part of the rhomboid fossa is formed by the medulla. Cool. On either side of the rhomboid fossa, you will see the cerebellar peduncles, which contain fibers that run between the cerebellum and all three parts of the brainstem. The inferior cerebellar peduncles contain fibers that go to the medulla. The middle cerebellar peduncles contain fibers that go to the pons. The superior cerebellar peduncles contain fibers that go to the midbrain. So that was all for the posterior surface of pons. Now let's go over to the next segment of this video and look at the internal surface of pons. But before we do that, I want you to keep in mind that the grey matter always contain cell bodies, so all structures within the grey matter are nuclei. White matter contain nerve fibers that form tracts. Now Let's take pons, and slice it up like this to look at the internal surface. So this is an outline of what pons look like. We will see the basilar circles here, so this is the anterior surface. We will see the middle cerebellar peduncles, and the rhombus fossa back here. So I hope this makes sense at this point. Before we dig into the structures on the surface of pons, we need to go through an important landmark that we use to separate pons into two parts. So here we see the internal part of the ear, the inner ear we call it, with the cochlea and the vestibulum. The cochlea, which is our primary organ of hearing, has a nerve called the cochlear nerve. The cochlear nerve will go directly towards the pons and then ascend towards the superior temporal gyrus as the lateral laminescus. But some fibers cross to the other side and then ascend to the superior temporal gyrus as the lateral laminescus. Now, Why am I telling you this? Because as these fibers cross within pons to the other side, they form the trapezoid body, as you see here. And the trapezoid body divides the internal surface of pons into two regions. The dorsal part becomes the tegmentum of pons, and the ventral part becomes the basilar part. Now let's go through the grey matter in the ventral and dorsal parts, and then do the white matter. So we'll start with the grey matter structures associated with the basilar part first. The only grey matter in the basilar part are the pontine nuclei. These pontine nuclei are a very significant part of Pons, because there's gonna be a tract that originates outside of the primary motor cortex, from the frontal lobe of the cortex, called the frontopontine tract. It will descend and synapse with the pontine nuclei, as you see here. And then once they synapse, these fibers will go to the cerebellum through the middle cerebellar peduncles. as the Pontocerebellar Tracts, so these fibers cross to the other side and then go to the cerebellum. And once they are at the cerebellum, the tracts will then travel towards the red nucleus of the midbrain as the cerebellorubral tract, and then they will descend as the rubrospinal tract to support voluntary movements. So the pontine nuclei are a very important part of Pons. The grey matter of the tegmentum consists of nuclei that belongs to the cranial nerve number 6 to 8 in the rhombus fossa. And we will cover the rhombus fossa in detail in a separate video, but for now, we will stick with the most important structures associated with Pons to really understand the anatomy of it. Next, we will see the reticular formation. And we will see the reticular formation along all parts of the brainstem. Then between the fibers of the trapezoid body, you will see small nuclei called the nuclei of the trapezoid body. which some of the fibers synapse with. So that was all the grey matter of pons. Now, let's go ahead and cover the white matter of the basilar part and the tegmentum of pons. And we'll start with the basilar part first. So here you'll only find descending tracts, or motor tracts. Remember earlier when we talked about the frontopontine tract and the pontocerebellar tracts, where fibers from the frontal cortex go down and synapse with the pontine nuclei in pons? and then fibers go from the pons to the cerebellum as the pontocerebellar tracts. Pontocerebellar tracts are descending tracts, so we need to color it as red. The other descending tract we see here is the frontopontine tract. You will see it depending on at which level you're looking at pons. But the frontopontine tract is actually a part of a bigger bundle of tracts called the corticopontine tract. The frontopontine tract was just an example. If the tracts originate from the occipital lobe, is called the occipitopontine tract, if it originates from the temporal lobe, it's called the temporopontine tract, and so on. That's why I specifically said the frontal lobe earlier, because the frontopontine tract comes from the frontal cortex. Notice that they all originate from different areas of the cerebral cortex, which are outside of the primary motor area of the brain. And because of that, these tracts are considered as extrapyramidal tracts. because they don't originate from the pyramidal cells of the primary motor cortex. So when we use the term corticopontine tract, you're really talking about the frontopontine tract, the occipitopontine tract, the temporopontine tract and the parietopontine tract. So you will find the corticopontine tract fibers here synapsing with the pontine nuclei. Awesome. The other descending tract is a pyramidal tract, called the corticospinal tract. It's a pyramidal tract because it originates from the pyramidal cells of the primary motor area in the cortex, and descend to the spinal cord to innervate skeletal muscles. Alongside the corticospinal tract, you will find the corticonuclear tract as well. It descends at the same area as the corticospinal tract, but the corticonuclear tract are responsible for voluntary control of muscles located in the head and neck. So that was all for the white matter of the basilar part, only descending tracts. Now let's do the white matter in the tegmentum and pons. The first one is the medial leminiscis. Now we need to repeat a few things in order to remember this one. So here we see a cross section of the spinal cord and the medulla. Remember that there were fibers that comes from the lower part of the body, which ascend as a graciofascial, and sensory fibers that came from the upper part of the body, which ascend as a cuneate fascial. I used the G in Graciofascial as genitals to remember that the graciofascial comes from the lower part of the body. So these fibers receive conscious proprioceptive information, as well as sensory input from mechanoreceptors. and they ascend to the Gratial and the Cuneate nuclei in the medulla. Then the fibers will leave as either the external arcuate fibers or internal arcuate fibers. The internal arcuate fibers will cross to the other side, and then they will ascend as the medial lemniscus, which is what you see here in Pons. They will ascend and go to the primary somatosensory area in the cerebral cortex, so that you're aware of sensory touch and vibration, as well as the position of your body parts. So that was the medial lemniscus. Then we have the spinal lemniscus. Remember when we talked about the cross section of the medulla, we had two spinothalamic tracts, the lateral and anterior one? They ascend together as the spinal lemniscus, and that's exactly what you see here in Pons. So it ascends to the cortex, to the primary somatosensory area as well, and they're responsible for conscious sensory input of pain, temperature, pressure and touch. So that is this one. Next we have the trigeminal lemniscus. The trigeminal lemniscus comes from the trigeminal ganglion, which is a part of the trigeminal nerve, the 5th cranial nerve. So Pons receives sensory input from this nerve, and then it crosses to the other side and ascends to the primary somatosensory area. So that is the trigeminal lemniscus. Then we have the anterior spinocerebellar tract. Remember when we talked about the medulla? that we had the posterior and anterior spinocerebellar tracts. The posterior spinocerebellar tract will go through the inferior cerebellar peduncle to go to the cerebellum. But the anterior one will go through the pons and midbrain, and then go to the cerebellum through the superior cerebellar peduncles. That's why we see it here, because it's going up to the midbrain to eventually go to the cerebellum. Then I wanna repeat something I mentioned earlier in this video. about the auditory nerve called the cochlear nerve that goes to the pons and then ascends as the lateral lemniscus to go to the superior temporal gyrus, which is the primary auditory area of the brain. Remember, some fibers are going to cross and then ascend to the primary temporal gyrus as the lateral lemniscus. But when they ascend after crossing, they will also ascend as the lateral lemniscus, which is an ascending tract that we need to include as well. So that was all the ascending tracts in the tegmentum of pons. Remember, blue represents sensory, or ascending tracts, and red represents descending, or motor tracts. Now let's do all the descending tracts in the tegmentum of pons. And the first one is the tectospinal tract. The tectospinal tract is called tectospinal because these fibers come from the tectum of the midbrain. So here is the midbrain, and posteriorly you'll find the tectum, so the tectospinal tract descend from here. And these are fibers that are associated with the coordinated eye and neck movements. And remember, since this tract originates from the brainstem, it's referred to as an extrapyramidal tract. Hence, it unconsciously moves your neck muscles with your eyes. So when you look at something, imagine you're looking at a hamburger, you're looking at it and you keep looking at it as it passes you, and your neck muscles unconsciously follow your eyes. That's what the tectospinal tract is responsible for. And that is our first descending tract of the tegmentum. The next one is called the rubrospalant tract. Remember we talked about the corticopontine tract, which are fibers that originate from anywhere outside of the primary motor area, that descend to synapse with the pontine nuclei. These fibers will go to the cerebellum as the pontocerebellar tract. From the cerebellum, fibers will go to the red nucleus of the midbrain as the cerebellorubral tract. And then Then they will descend as the rubrospinal tract. Notice that I said that these fibers do not originate from the pyramidal cells of the primary motor cortex. That's why they are referred to as extrapyramidal tract. They don't initiate movement, but they support and coordinate the voluntary movements. So that is the rubrospinal tract. Next we have the reticulospinal tract, which is a part of the balance and posture system. They come from the reticular formation inside of the brainstem. The reticular system are responsible for sleep, alertness, cardiovascular control, breathing and all of those vital things, but they are also responsible for motor control, like your balance and posture, through the reticulospinal tract. So that is this one. Next we have the vestibulospinal tract, and to understand this one, we need to involve the inner ear again. Because the inner ear has the vestibular system. And the vestibular system has crystals within it that monitors your balance, and it transmits impulses to your brain and then down to your muscles to keep your balance. So whenever your head is tilted, or you're upside down, or you're about to fall, all of those is monitored and controlled by your vestibular system. So it helps with balance and posture. Alright, So let's now clean up the labels and add a little color to differentiate them. There is one more tract that we need to mention, which is the medial longitudinal fasciculus, which descend and is present only in the cervical segments in the spinal cord. This tract coordinates the involuntary movements of the head and neck and eyes through synapses between the cranial nerves number 3, 4, 6 and 11. So that was all I had for the internal surfaces of pons. Now I made this table for the nuclei and tracts we will find along the basilar part of the endotigmentum of Pons, along with a little description of them. Now this is where this video gets scary. I am going to make all of these names disappear, and can you, from the beginning, tell me what is the name of number 1? What is the name of number 4? Where does number 14 go, and where does number 12 go? If you can do that, then you've grasped the anatomy of Pons fully. If you find this video helpful, please put a like, share, comment, whatever you find convenient to you. The next video is going to be about the fourth ventricle and the rhomboid fossa.

What's up, Merete here! Let's continue the anatomy of the central nervous system. In this segment, we will cover the complete anatomy of the Pons.

So remember, the central nervous system consists of two parts, the Encephalon and the spinal cord. The Encephalon is then further subdivided into specific parts. We have the brainstem, which consists of the medulla, pons and the midbrain, or the mesencephalon.

We have the cerebellum back here, and the diencephalon and the tenencephalon. So our focus in this video is going to be ponds, which is here. So in this video, we're first going to cover the external surfaces of ponds, basically look at its topography and what structures you will find from an anterior view and a posterior view. And then we're going to slice up the ponds and look at the internal surface, basically see how the gray matter and the white matter are arranged within it.

And then I made a little quiz at the end of this video, which might help you if you need to memorize. Alright, so we can start by replacing this picture with a little more realistic one. Pons is located here, lying above the medulla and in front of the cerebellum, and down here you can see the spinal cord.

Now if you remove a part of the cerebral cortex, you'll be able to see the rest of the pons, as well as the mesencephalon, or the midbrain, which is the most superior part of the brainstem. Alright, now, externally, your pons have two surfaces, it has an anterior surface, and a posterior surface. Let's now cover the typical morphology of these two surfaces.

Starting with the anterior surface first. And we'll do that by looking at the brainstem from this perspective. We'll see this. So again, Pons is this prominent bulb you see here.

In the midline of the anterior surface, there's a sulcus called the basilar sulcus. Laterally on either side, you'll see that the Pons turns backwards towards the cerebellum. And that is because Pons forms the middle cerebellar peduncles on either side.

which continue into the cerebellum back here. That was the general morphology of the anterior surface of Pons, but there are some cranial nerves that leave the brainstem at this area. We have 12 cranial nerves in our body, and each serves its particular function for our brain, but from the anterior part of Pons, you will see a nerve that goes out between the pyramids of the middle of the lingara and Pons.

This nerve is the 6th cranial nerve, the nervus abducens, that goes to the lateral extraocular muscles of the eyes to help with abduction of the eyeballs. Then between the olives and the middle cerebellar peduncles, you will find the cranial nerve number 7, the facial nerve which provides motor innervation for the facial muscles that help with facial expressions, and the cranial nerve number 8, the vestibulocochlear nerve, for hearing imbalance. The last nerve is at the surface of the pons, and that is the fifth cranial nerve, the nervus trigemnus.

It's a very large nerve that goes to your facial region to provide sensory innervation, motor innervation as well as parasympathetic innervation for the glands. So all of these nerves emerge from the anterior area of Pons. Now let's turn this model around and look at the posterior surface.

From the posterior view, you will see that the cerebellum covers the whole posterior area of Pons. So let's go ahead and remove the cerebellum. So Pons is here, above the medulla and below the midbrain, or mesencephalon. Pons doesn't really have any specific structures on its own, rather it works with the medulla and mesencephalon in forming certain structures. One of them is the rhomboid fossa.

The rhomboid fossa has many nuclei for the cranial nerves, and is a very important landmark for tracts and nuclei. I will cover this in detail in my next video, but for now, I wanted to know that the upper part of the rhomboid fossa is formed by pons, and the lower part of the rhomboid fossa is formed by the medulla. Cool.

On either side of the rhomboid fossa, you will see the cerebellar peduncles, which contain fibers that run between the cerebellum and all three parts of the brainstem. The inferior cerebellar peduncles contain fibers that go to the medulla. The middle cerebellar peduncles contain fibers that go to the pons.

The superior cerebellar peduncles contain fibers that go to the midbrain. So that was all for the posterior surface of pons. Now let's go over to the next segment of this video and look at the internal surface of pons. But before we do that, I want you to keep in mind that the grey matter always contain cell bodies, so all structures within the grey matter are nuclei.

White matter contain nerve fibers that form tracts. Now Let's take pons, and slice it up like this to look at the internal surface. So this is an outline of what pons look like.

We will see the basilar circles here, so this is the anterior surface. We will see the middle cerebellar peduncles, and the rhombus fossa back here. So I hope this makes sense at this point.

Before we dig into the structures on the surface of pons, we need to go through an important landmark that we use to separate pons into two parts. So here we see the internal part of the ear, the inner ear we call it, with the cochlea and the vestibulum. The cochlea, which is our primary organ of hearing, has a nerve called the cochlear nerve.

The cochlear nerve will go directly towards the pons and then ascend towards the superior temporal gyrus as the lateral laminescus. But some fibers cross to the other side and then ascend to the superior temporal gyrus as the lateral laminescus. Now, Why am I telling you this?

Because as these fibers cross within pons to the other side, they form the trapezoid body, as you see here. And the trapezoid body divides the internal surface of pons into two regions. The dorsal part becomes the tegmentum of pons, and the ventral part becomes the basilar part.

Now let's go through the grey matter in the ventral and dorsal parts, and then do the white matter. So we'll start with the grey matter structures associated with the basilar part first. The only grey matter in the basilar part are the pontine nuclei.

These pontine nuclei are a very significant part of Pons, because there's gonna be a tract that originates outside of the primary motor cortex, from the frontal lobe of the cortex, called the frontopontine tract. It will descend and synapse with the pontine nuclei, as you see here. And then once they synapse, these fibers will go to the cerebellum through the middle cerebellar peduncles.

as the Pontocerebellar Tracts, so these fibers cross to the other side and then go to the cerebellum. And once they are at the cerebellum, the tracts will then travel towards the red nucleus of the midbrain as the cerebellorubral tract, and then they will descend as the rubrospinal tract to support voluntary movements. So the pontine nuclei are a very important part of Pons. The grey matter of the tegmentum consists of nuclei that belongs to the cranial nerve number 6 to 8 in the rhombus fossa.

And we will cover the rhombus fossa in detail in a separate video, but for now, we will stick with the most important structures associated with Pons to really understand the anatomy of it. Next, we will see the reticular formation. And we will see the reticular formation along all parts of the brainstem. Then between the fibers of the trapezoid body, you will see small nuclei called the nuclei of the trapezoid body. which some of the fibers synapse with.

So that was all the grey matter of pons. Now, let's go ahead and cover the white matter of the basilar part and the tegmentum of pons. And we'll start with the basilar part first. So here you'll only find descending tracts, or motor tracts.

Remember earlier when we talked about the frontopontine tract and the pontocerebellar tracts, where fibers from the frontal cortex go down and synapse with the pontine nuclei in pons? and then fibers go from the pons to the cerebellum as the pontocerebellar tracts. Pontocerebellar tracts are descending tracts, so we need to color it as red.

The other descending tract we see here is the frontopontine tract. You will see it depending on at which level you're looking at pons. But the frontopontine tract is actually a part of a bigger bundle of tracts called the corticopontine tract. The frontopontine tract was just an example. If the tracts originate from the occipital lobe, is called the occipitopontine tract, if it originates from the temporal lobe, it's called the temporopontine tract, and so on.

That's why I specifically said the frontal lobe earlier, because the frontopontine tract comes from the frontal cortex. Notice that they all originate from different areas of the cerebral cortex, which are outside of the primary motor area of the brain. And because of that, these tracts are considered as extrapyramidal tracts.

because they don't originate from the pyramidal cells of the primary motor cortex. So when we use the term corticopontine tract, you're really talking about the frontopontine tract, the occipitopontine tract, the temporopontine tract and the parietopontine tract. So you will find the corticopontine tract fibers here synapsing with the pontine nuclei.

Awesome. The other descending tract is a pyramidal tract, called the corticospinal tract. It's a pyramidal tract because it originates from the pyramidal cells of the primary motor area in the cortex, and descend to the spinal cord to innervate skeletal muscles. Alongside the corticospinal tract, you will find the corticonuclear tract as well. It descends at the same area as the corticospinal tract, but the corticonuclear tract are responsible for voluntary control of muscles located in the head and neck.

So that was all for the white matter of the basilar part, only descending tracts. Now let's do the white matter in the tegmentum and pons. The first one is the medial leminiscis. Now we need to repeat a few things in order to remember this one.

So here we see a cross section of the spinal cord and the medulla. Remember that there were fibers that comes from the lower part of the body, which ascend as a graciofascial, and sensory fibers that came from the upper part of the body, which ascend as a cuneate fascial. I used the G in Graciofascial as genitals to remember that the graciofascial comes from the lower part of the body. So these fibers receive conscious proprioceptive information, as well as sensory input from mechanoreceptors. and they ascend to the Gratial and the Cuneate nuclei in the medulla.

Then the fibers will leave as either the external arcuate fibers or internal arcuate fibers. The internal arcuate fibers will cross to the other side, and then they will ascend as the medial lemniscus, which is what you see here in Pons. They will ascend and go to the primary somatosensory area in the cerebral cortex, so that you're aware of sensory touch and vibration, as well as the position of your body parts.

So that was the medial lemniscus. Then we have the spinal lemniscus. Remember when we talked about the cross section of the medulla, we had two spinothalamic tracts, the lateral and anterior one? They ascend together as the spinal lemniscus, and that's exactly what you see here in Pons. So it ascends to the cortex, to the primary somatosensory area as well, and they're responsible for conscious sensory input of pain, temperature, pressure and touch.

So that is this one. Next we have the trigeminal lemniscus. The trigeminal lemniscus comes from the trigeminal ganglion, which is a part of the trigeminal nerve, the 5th cranial nerve. So Pons receives sensory input from this nerve, and then it crosses to the other side and ascends to the primary somatosensory area.

So that is the trigeminal lemniscus. Then we have the anterior spinocerebellar tract. Remember when we talked about the medulla? that we had the posterior and anterior spinocerebellar tracts.

The posterior spinocerebellar tract will go through the inferior cerebellar peduncle to go to the cerebellum. But the anterior one will go through the pons and midbrain, and then go to the cerebellum through the superior cerebellar peduncles. That's why we see it here, because it's going up to the midbrain to eventually go to the cerebellum. Then I wanna repeat something I mentioned earlier in this video. about the auditory nerve called the cochlear nerve that goes to the pons and then ascends as the lateral lemniscus to go to the superior temporal gyrus, which is the primary auditory area of the brain.

Remember, some fibers are going to cross and then ascend to the primary temporal gyrus as the lateral lemniscus. But when they ascend after crossing, they will also ascend as the lateral lemniscus, which is an ascending tract that we need to include as well. So that was all the ascending tracts in the tegmentum of pons. Remember, blue represents sensory, or ascending tracts, and red represents descending, or motor tracts.

Now let's do all the descending tracts in the tegmentum of pons. And the first one is the tectospinal tract. The tectospinal tract is called tectospinal because these fibers come from the tectum of the midbrain.

So here is the midbrain, and posteriorly you'll find the tectum, so the tectospinal tract descend from here. And these are fibers that are associated with the coordinated eye and neck movements. And remember, since this tract originates from the brainstem, it's referred to as an extrapyramidal tract.

Hence, it unconsciously moves your neck muscles with your eyes. So when you look at something, imagine you're looking at a hamburger, you're looking at it and you keep looking at it as it passes you, and your neck muscles unconsciously follow your eyes. That's what the tectospinal tract is responsible for. And that is our first descending tract of the tegmentum.

The next one is called the rubrospalant tract. Remember we talked about the corticopontine tract, which are fibers that originate from anywhere outside of the primary motor area, that descend to synapse with the pontine nuclei. These fibers will go to the cerebellum as the pontocerebellar tract.

From the cerebellum, fibers will go to the red nucleus of the midbrain as the cerebellorubral tract. And then Then they will descend as the rubrospinal tract. Notice that I said that these fibers do not originate from the pyramidal cells of the primary motor cortex.

That's why they are referred to as extrapyramidal tract. They don't initiate movement, but they support and coordinate the voluntary movements. So that is the rubrospinal tract. Next we have the reticulospinal tract, which is a part of the balance and posture system. They come from the reticular formation inside of the brainstem.

The reticular system are responsible for sleep, alertness, cardiovascular control, breathing and all of those vital things, but they are also responsible for motor control, like your balance and posture, through the reticulospinal tract. So that is this one. Next we have the vestibulospinal tract, and to understand this one, we need to involve the inner ear again.

Because the inner ear has the vestibular system. And the vestibular system has crystals within it that monitors your balance, and it transmits impulses to your brain and then down to your muscles to keep your balance. So whenever your head is tilted, or you're upside down, or you're about to fall, all of those is monitored and controlled by your vestibular system. So it helps with balance and posture. Alright, So let's now clean up the labels and add a little color to differentiate them.

There is one more tract that we need to mention, which is the medial longitudinal fasciculus, which descend and is present only in the cervical segments in the spinal cord. This tract coordinates the involuntary movements of the head and neck and eyes through synapses between the cranial nerves number 3, 4, 6 and 11. So that was all I had for the internal surfaces of pons. Now I made this table for the nuclei and tracts we will find along the basilar part of the endotigmentum of Pons, along with a little description of them.

Now this is where this video gets scary. I am going to make all of these names disappear, and can you, from the beginning, tell me what is the name of number 1? What is the name of number 4? Where does number 14 go, and where does number 12 go? If you can do that, then you've grasped the anatomy of Pons fully.

If you find this video helpful, please put a like, share, comment, whatever you find convenient to you. The next video is going to be about the fourth ventricle and the rhomboid fossa.

Transcript for:Understanding the Pons in the CNS

Transcript for:
Understanding the Pons in the CNS