Medulla Oblongata Anatomy - External & Internal (White & Grey matter) + QUIZ

Summary

This educational video script delves into the anatomy of the medulla oblongata, a vital part of the brainstem. It covers both external and internal features, highlighting the medulla's topography, grooves, bumps, and cranial nerve connections. The script also explores the medulla's internal grey and white matter, detailing the nuclei and tracts responsible for essential functions like voluntary muscle movement and balance. A quiz at the end challenges viewers' understanding, promising a comprehensive grasp of this complex brain region.

Takeaways

• 🧠 The central nervous system is composed of the encephalon and the spinal cord, with the encephalon further divided into the brainstem, cerebellum, diencephalon, and telencephalon.
• 🌟 The medulla oblongata is a critical part of the brainstem, situated above the spinal cord and below the pons, and it connects with the cerebellum.
• 📏 The medulla oblongata is approximately 2.5 cm in length and plays a significant role despite its small size.
• 👀 The anterior surface of the medulla features five grooves: the anterior median fissure, right and left anterolateral sulci, and right and left posterolateral sulci.
• 🔍 The pyramids of the medulla, located medially, contain corticospinal tracts responsible for voluntary skeletal muscle movement.
• 🔗 The olives of the medulla are lateral to the pyramids and are associated with the olivary nucleus.
• 💉 The 12th cranial nerve, the hypoglossal nerve, emerges from the anterolateral sulcus and controls most tongue muscles.
• 🔊 The glossopharyngeus, vagus, and accessory nerves emerge from the posterolateral sulci, serving swallowing, organ regulation, and neck muscle movement.
• 🔙 The posterior surface of the medulla includes the posterior median sulcus, gracile and cuneate fascicles, and inferior cerebellar peduncles.
• 🧬 The internal structure of the medulla consists of grey matter (nuclei) and white matter (tracts), with the grey matter containing cell bodies and the white matter containing nerve fibers.
• 🚀 Key tracts include the gracile and cuneate tracts for sensory information, spinocerebellar tracts for proprioception, and corticospinal tracts for voluntary muscle control.

Q & A

What are the two main parts of the central nervous system?

The central nervous system consists of the encephalon and the spinal cord.

What is the medulla oblongata and where is it located?

The medulla oblongata is a part of the brainstem located above the spinal cord and below the pons, and it connects with the cerebellum.

What is the length of the medulla oblongata?

The length of the medulla oblongata is about 2.5 cm.

What are the two surfaces of the medulla oblongata?

The medulla oblongata has an anterior surface and a posterior surface.

What are the five grooves found on the anterior surface of the medulla oblongata?

The five grooves on the anterior surface of the medulla oblongata are the Anterior median fissure, Right and Left Anterolateral sulci, and Right and Left posterolateral sulci.

What structure contains the corticospinal tracts and is located between the anterior median fissure and the anterolateral sulci?

The Pyramids of the Medulla Oblongata contain the corticospinal tracts.

Which cranial nerve is responsible for the movement of most of the muscles in the tongue?

The 12th cranial nerve, the hypoglossal nerve, is responsible for the movement of most of the muscles in the tongue.

What is the function of the glossopharyngeus, vagus, and accessory cranial nerves that emerge from the medulla?

The glossopharyngeus is for coordinating swallowing and the gag reflex, the vagus regulates functions of most organs through parasympathetic fibers, and the accessory nerve is for neck muscles.

What are the structures found on the posterior surface of the medulla oblongata?

On the posterior surface of the medulla oblongata, you find the Posterior median sulcus, Gracile Fascicle, Cuneate Fascicle, and inferior cerebellar peduncles.

What are the functions of the gracile and cuneate nuclei within the medulla oblongata?

The gracile nucleus receives sensory input from the lower part of the body, and the cuneate nucleus receives input from the upper part of the body.

How does the medulla oblongata contribute to the balance and posture of the body?

The medulla oblongata contributes to balance and posture through tracts like the vestibulospinal tract, olivospinal tract, and reticulospinal tracts.

Outlines

00:00

🧠 Introduction to the Medulla Oblongata

This section introduces the anatomy of the central nervous system, focusing on the medulla oblongata. It explains the division of the central nervous system into the encephalon and the spinal cord, with further subdivision of the encephalon into the brainstem, cerebellum, diencephalon, and telencephalon. The medulla oblongata's position between the spinal cord and pons is highlighted, along with its connection to the cerebellum. The video promises to cover both the external and internal surfaces of the medulla, including its topography and structures visible from anterior and posterior views. The length of the medulla is noted as approximately 2.5 cm, emphasizing its small size but significant role in the brain.

05:02

👁️‍🗨️ Anatomy of the Medulla's External Surface

This paragraph delves into the external surface features of the medulla oblongata. It describes the anterior surface, which includes the anterior median fissure, anterolateral sulci, and posterolateral sulci. The Pyramids of the Medulla Oblongata, located medially, contain corticospinal tracts responsible for voluntary muscle movement. The Olives of the Medulla, laterally positioned, house the olivary nucleus. The paragraph also discusses the exit points of the 12th cranial nerve (hypoglossal nerve) and three other cranial nerves (9th, 10th, and 11th) from the sulci, detailing their functions. The posterior surface is then examined, featuring the posterior median sulcus, gracile fascicle, and cuneate fascicle, which are involved in sensory input from different parts of the body. The inferior cerebellar peduncles, connecting the cerebellum to the medulla, are also mentioned.

10:05

🔍 Internal Structure of the Medulla Oblongata

The internal surface of the medulla is explored in this section, distinguishing between grey matter (nuclei) and white matter (tracts). The grey matter includes the Gracile Nucleus, Cuneate Nuclei, olivary nuclei, and the Reticular Formation. The white matter consists of tracts such as the inferior cerebellar peduncle, which connects to the cerebellum. The discussion continues with the function of various tracts, including the ascending sensory tracts (gracile and cuneate fascicles) and the descending motor tracts (corticospinal tract). The decussation of the pyramids, where many corticospinal tract fibers cross, is also explained. The summary provides a detailed look at how these structures facilitate different sensory and motor functions within the brainstem.

15:12

🌐 Tracts and Nuclei within the Medulla

This paragraph provides a comprehensive overview of the various tracts and nuclei found within the medulla oblongata. It describes the function of ascending tracts like the spinocerebellar tracts, which contribute to unconscious proprioception, and the spinothalamic tracts, which transmit conscious sensory information related to pain, temperature, and touch. The descending tracts are also detailed, including the corticospinal tract responsible for voluntary muscle movement, the vestibulospinal tract for balance and posture, and the olivospinal tract, which aids in balance. Other tracts like the rubrospinal, tectospinal, and reticulospinal tracts are also covered, emphasizing their roles in fine motor coordination, eye and neck muscle coordination, and balance, respectively. The medial longitudinal fascicle, which coordinates involuntary head and neck movements, is also mentioned. The paragraph concludes with a challenge for viewers to recall the functions and pathways of the numbered structures without visual aids.

Keywords

💡Central Nervous System

The central nervous system (CNS) is the part of the nervous system consisting of the brain and spinal cord. It plays a crucial role in receiving, processing, and transmitting information throughout the body. In the video, the CNS is divided into two main parts: the encephalon (brain) and the spinal cord. The focus of the video is on the medulla oblongata, a part of the brainstem within the encephalon.

💡Medulla Oblongata

The medulla oblongata is a structure located at the base of the brain, forming part of the brainstem. It is responsible for controlling vital functions such as breathing, heart rate, and blood pressure. The video script provides a detailed anatomy lesson on the medulla, including its external and internal surfaces, and its connections to other parts of the brain.

💡Brainstem

The brainstem is a part of the brain that connects to the spinal cord and is situated beneath the cerebrum. It is composed of three parts: the medulla oblongata, pons, and midbrain. The brainstem is essential for life-sustaining functions, and the video script discusses the medulla's role within it.

💡Cerebellum

The cerebellum is a region of the brain that is located at the back of the head, beneath the cerebrum. It plays a key role in motor control, coordination, and balance. In the script, the cerebellum is mentioned in relation to its position relative to the medulla oblongata.

💡Anterior Surface

The anterior surface of the medulla oblongata is the front-facing side of the medulla. The video script describes the topography of this surface, including the presence of grooves and bumps such as the anterior median fissure, anterolateral sulci, and the pyramids of the medulla oblongata.

💡Posterior Surface

The posterior surface of the medulla oblongata is the back-facing side of the medulla. The script explains that this surface contains the posterior median sulcus and the gracile and cuneate tubercles, which are important for sensory information processing.

💡Grey Matter

Grey matter in the context of the nervous system refers to regions composed of neuronal cell bodies, as opposed to white matter, which consists of myelinated axons. The script describes the grey matter of the medulla, including nuclei such as the gracile nucleus and the olivary nuclei.

💡White Matter

White matter is composed of myelinated nerve fibers that facilitate communication between different parts of the brain. The video script discusses the arrangement of white matter in the medulla, including tracts such as the corticospinal tract and the medial lemniscus.

💡Cranial Nerves

Cranial nerves are the nerves that emerge directly from the brain, as opposed to spinal nerves that emerge from the spinal cord. The script mentions that there are 12 cranial nerves, and it specifically discusses the 12th cranial nerve (hypoglossal nerve) and cranial nerves 9, 10, and 11 as they relate to the medulla.

💡Corticospinal Tract

The corticospinal tract is a bundle of nerve fibers that carries signals from the cerebral cortex to the spinal cord, playing a key role in voluntary motor control. The video script explains that the majority of fibers in the corticospinal tract decussate at the lower border of the medulla oblongata.

💡Reticular Formation

The reticular formation is a network of neurons located in the brainstem, involved in regulating various autonomic functions, including sleep, respiration, and cardiovascular control. The script mentions the reticular formation as part of the grey matter within the medulla.

Highlights

The central nervous system consists of the encephalon and the spinal cord.

The brainstem is composed of the medulla, pons, and midbrain.

The medulla oblongata is a critical part of the brainstem.

The medulla's external surfaces include anterior and posterior views.

The anterior surface of the medulla features five grooves.

The Pyramids of the Medulla Oblongata contain corticospinal tracts.

The Olives of the Medulla contain the olivary nucleus.

The 12th cranial nerve, the hypoglossal nerve, emerges from the medulla.

Cranial nerves 9, 10, and 11 exit from the posterolateral sulci.

The posterior surface of the medulla forms part of the rhomboid fossa.

The medulla's internal surface is divided into grey and white matter.

The Gracile and Cuneate Nuclei are part of the medulla's grey matter.

The medulla contains tracts for both ascending and descending nerve fibers.

The corticospinal tract is a major descending tract in the medulla.

The vestibulospinal tract is involved in balance and posture.

The reticulospinal tract originates from the reticular formation.

The medial longitudinal fascicle coordinates head and neck movements.

Transcripts

What’s up. Meditay Here. Let’s continue  the anatomy of the Central Nervous System.  

In this segment, we’ll cover the complete  anatomy of the medulla oblongata. 

So remember, the central nervous  system consists of two parts:  

the encephalon and the spinal cord. The encephalon  is then further divided 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,  then the diencephalon and the telencephalon. 

Our focus in this video is going to be  the medulla oblongata, which is here. 

So in this video, we’re first going to cover  the external surfaces of the medulla. Basically,  

look at its topography and what structures you’ll  find from an anterior view and a posterior view.  

Then we’re gonna slice up the medulla  and look at the internal surface.  

Basically, see how the grey matter and white  matter are arranged within it. And at the end  

of this video, you’ll find a quiz that you’ll  hopefully be able to pass based on this video. 

Alright, so we can start by replacing  this picture with a more realistic one. 

The medulla is here, lying right above the spinal  cord and below the pons. The medulla also connects  

with the cerebellum, so you’ll find the cerebellum  behind the superior part of the medulla oblongata. 

And all of these structures lie within  our cranial cavity within the skull.  

So topographically, the medulla starts  at the level of the foramen magnum,  

which is the distinct border between the  spinal cord and the medulla. And in the front,  

the medulla lies on the clivus, which remember  is at the anterior portion of the occipital bone.  

The length of the medulla oblongata is  about 2,5cm, so it’s a quite small portion  

of your brain but a very important one. Alright. Now. Externally, your medulla has  

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. So if we look at the  

brainstem from this perspective, you’ll see this. And again, the medulla oblongata is here in green.  

So there are 5 grooves that you can see on the  anterior surface. The first one is the Anterior  

median fissure, then laterally to that, you  can see the Right and Left Anterolateral sulci,  

and laterally to that again, you’ll see  the right and left posterolateral sulci. 

And notice between these grooves, there are bumps  that are very characteristic for the medulla.  

The first bumps are called the Pyramids of the  Medulla Oblongata. And they’re located medially  

between the anterior median fissure and the Right  and Left anterolateral sulci. The pyramids contain  

the corticospinal tracts, which come from the  pyramidal cells of the primary motor cortex. Which  

remember is responsible for voluntary movements of  our skeletal muscles. A majority of the fibers in  

the corticospinal tract will decussate at  the lower border, forming the decussation  

of the pyramid. We’ll talk more about that when  we talk about the internal surface of the medulla.  

I just mentioned it now to give you something to  remember the pyramids with. Alright. Laterally to  

the Pyramids, you’ll find the Olives of the  Medulla, which contain the olivary nucleus.

So these are the bumps. But some cranial nerves  go out from the medulla through these grooves.  

We have 12 cranial nerves in our body and each  serves its particular function in the brain,  

but from the anterior part of the medulla. You’ll  see the 12th cranial nerve, the hypoglossal nerve,  

going out from the anterolateral sulci. The 12th  cranial nerve is responsible for the movement of  

most of the muscles in your tongue, so this  nerve goes out from the anterolateral sulcus  

and then goes to the tongue. So that is  that. Then on the posterolateral sulci,  

there are three cranial nerves that go out.  These are the cranial nerve number 9, number 10,  

and number 11. The glossopharyngeus, Vagus, and  the Accessorius. Glossopharyngeus is mainly for  

coordinating the swallowing process and  is also responsible for the gag reflex.  

Vagus goes to most organs in your body and  regulates their function. Mainly parasympathetic  

fibers. And the last accessories is an  accessory nerve for the neck muscles. 

So that is the anterior view. Now let’s turn the picture around  

and look at the posterior view. So the posterior  part of the medulla is highlighted in green,  

and if we now remove the cerebellum, you'll  be able to see the rest of the medulla. Now  

the upper part of the medulla oblongata takes part  in forming the so called rhomboid fossa, which is  

a fossa that contain many nuclei. The lower part  of the rhomboid fossa is considered a part of the  

medulla oblongata, but we’ll cover the rhomboid  fossa briefly in a separate video to really focus  

on the anatomy of the medulla for now. So on the posterior surface,  

you’ll find the Posterior median sulcus. On  either side of the posterior emdian sulcus,  

you’ll find the Gracile Fascicle, remember  we talked about this one when we talked about  

the spinal cord. The gracile fascicle received  sensory input form the Lower part of your body,  

and sends it up through the spinal cord and  through the medulla, to the gracile nuclei,  

which form a gracile tubercule. Laterally to  the gracile fascicle is the Cuneate Fascicle,  

which receives input from the upper parts  of your body and forms the Cuneate Tubercle. 

From the posterior surface of the medulla,  you’ll also be able to see the inferior  

cerebellar peduncles, which are fibers that go  within the medulla, to the cerebellum, as you  

see here. So the inferior cerebellar peduncles  connect the cerebellum and the medulla together. 

So that was all for the  external surface of the medulla. 

Now let’s go ahead and cover the internal  surface of the medulla oblongata. 

The internal surface of the medulla consists of  two parts, grey matter, and white matter. And  

just to remind you again, that grey matter always  contains cell bodies, so when we talk about the  

grey matter, we talk about nuclei. White matter  always contains nerve fibers, which form tracts. 

Now, let’s finally take the medulla and give it a  good slice, to focus on the internal surface. In  

theory, if you wanna go deep within the neurology  of it, the internal surface of the medulla differs  

along the superior part and the inferior part of  it. Meaning if you cut the medulla at different  

regions, you’ll find different structures. But in  this video, I’ll just slice at the superior part  

of the medulla and talk about the most significant  parts of the internal surface while highlighting  

which parts below to which level so that it  gets easier to understand the medulla oblongata. 

So here is the general outline of the medulla.  We’ll be able to see the Antrior median fissure,  

the Pyramid of the medulla and the Olives. And  posteriorly, we’ll see the Gracile Tubercle and  

the Cuneate Tubercle. And on the sides here  we can see the inferior cerebellar peducle,  

which remember connects the cerebellum with the  medulla. So I hope you’re following so far. Let’s  

now go ahead and fill upp the internal surface  with structures, starting with the grey matter. 

We’re first going to have the Gracile Nucleus  medially, within the gracile tubercle. Then  

laterally to that, we have the Cuneate Nuclei,  within the cuneate Tubercles. Within the Olives,  

we have the olivary nuclei, and then in the  middle, we have the Reticular formation,  

which is a network of grey matter throughout  the brainstem. I’ll show you this in a little  

more detail later. Then lastly, you’ll find many  nuclei of the cranial nerves within the medulla,  

at the region of the Rhomboid Fossa. You’ll  find the cranial nuclei number 8-12. Again,  

these are not significant for the understanding  of the medulla anatomy, for now, so I’ll mention  

these in the video about the rhomboid fossa.  So these are the grey matter of the medulla  

oblongata. Let’s now see how these nuclei are  associated with tracts within your brainstem  

by looking at the white matter of the medulla. While we’re talking about the tracts,  

I’ll represent the blue color as ascending  tracts or sensory tracts. And the red color  

will represent motor tracts or descending tracts.  Alright, so first off, we’ll start with the  

fibers associated with the nucleus gracilis, and  we’ll add the spinal cord to visualize this one.  

Fibers that synapse with the nucleus gracilis are  sensory fibers that come from the lower parts of  

the body and through the spinal cord. These fiber  will then ascent and synapse with nucleus gracilis  

in the medulla. Um, I use the letter G in Gracile  nucleus as genitals to remember that nucleus  

gracilis receives input from the lower parts of  the body. And it receives conscious epicritic  

sensibility. With is conscious proprioception.  Remember, this is kinesia, joint position,  

and the sense of force. But it also receives input  from mechanoreceptors, which is responsible for  

two-point discrimination, which means the minimal  distance between two points required for you to  

detect it as two points and not one. So if these  two pencils were veeery cloe to each other, you’d  

have detected that prick as one point and not  two. So two-point discrimination is your ability  

to discriminate between two points. Meaning the  minimum distance needed for you to sense those  

pencils as two points, not one. It also receives  input like vibration and touch. All of these are  

sent to the nucleus gracilis. The cuneate nucleus  receives input from the upper part of your body  

through the cuneate fascicle, which also senses  epicritic sensibility. Alright. Now from the  

gracile nucleus and the Cuneate nucleus, where do  the fibers go? Well, they split into two pathways. 

They split into fibers that go through the  inferior cerebellar peduncle, as you see here,  

as fibers called the external arcuate fibers.  And remember, since they go through the inferior  

cerebellar peduncle, they’ll go to the cerebellum. Now. Since we have external arcuate fibers,  

we’ll also have internal arcuate fibers. And  these fibers will cross over to the other side,  

as you see here. So these are called the internal  arcuate fibers. And since both sides cross to the  

other side, they decussate to form the decussation  of the lemnisci. They’re called that because once  

they cross, they start to ascend upwards  in your CNS, as the medial lemniscus. To go  

further through the diencephalon and then to the  primary somatosensory area in the cerebral cortex. 

Next, we have two tracts on either  side. Called the spinocerebellar  

tracts. Remember we talked about these  when we talked about the spinal cord?  

We have an anterior spinocerebellar tract and a  posterior spinocerebellar tract. Remember, if the  

tract ends with the work Cerebellum, that means  that these tracts will ascend to the cerebellum.  

But the way these two tracts do that is a little  bit different. The posterior spinocerebellar  

tracts are closest to the inferior cerebellar  peduncle, so it’ll go through the inferior  

cerebellar peduncle to the cerebellum. The anterior spinocerebellar tract  

will ascent through the medulla oblongata through  pons and then to the midbrain. From the midbrain,  

it’ll go into the cerebellum through  the superior cerebellar peduncle. 

And since these tracts go to the cerebellum,  that means they’re responsible for  

unconscious proprioception, like giving  information about the posture and joints. 

After that we have two other ascending  tracts, called Spinothalamic tracts.  

We have an anterior spinothalamic tract and  a lateral spinothalamic tract. These tracts  

are both going to go to the primary somatosensory  area in the cortex. And as they ascent, they get  

the name the spinal lemniscus. And since they go  to the cerebral cortex, that means they provide  

conscious sensory information. And that is for  Pain and temperature and pressure and touch.  

So that was all the ascending tracts  I wanted to mention in the medulla.  

Now let’s do the descending tracts. And the first one is the one that’s  

the most significant of them, located within the  pyramids of the medulla, called the corticospinal  

tract. These fibers will originate from the  pyramidal cells of the primary motor cortex,  

and then they will descend. 80 percent of  the fibers that descend, will cross at the  

medulla oblongata region, like this, and form the  deccusation of pyramids. After they cross, they  

will descend as the lateral corticospinal tract.  The remaining 20% will descend as the anterior  

corticospinal tract, and only decussate at the  region they exit at the spinal cord. And since  

they come from the pyramidal cells of the primary  motor cortex, that means they’re responsible  

for the voluntary movement of skeletal muscles. Next there are the corticonuclear tracts, which  

descend at the same areas as the corticospinal  tract. And the corticonuclear tracts are  

responsible for the voluntary control  of muscles located in the head and neck. 

The next descending tract is the vestibulospinal  tract. Inside of your ear, the inner ear,  

you have a system called the vestibular system.  The vestibular system has crystals within it  

sensing the position of your head, wether your  head is tilted upside down, or to the side, all of  

that is sensed and through the vestibular nerve,  it’s sent to the brainstem, and then down to your  

spinal cord to keep your balance and posture.  So the vestibulospinal tract is responsible for  

keeping your balance and posture. And this happens  unconsciously because this tract doesn’t originate  

from your cortex—so unconscious balance of  your body is the function of this tract. 

So that is the Vestibulospinal tract. Next we  have the Olivospinal tract, which comes from the  

olivary nuclei. The olivospinal tract also takes  part in helping you keep your balance and posture. 

Through the olivary nuclei, there are  also fibers that go to the cerebellum,  

called the olivocerebellar tract, which  aid the balance system. So that’s these. 

Next, we have the Rubrospinal tract. Rubro means  red, and the reason why they’re called rubrospinal  

tract Is because we have red nuclei located inside  the midbrain of the brainstem. So these fibers are  

extrapyramidal because they’re not originating  from the primary motor cortex. They come  

from the red nucleus of the midbrain, and they  descend as the rubrospinal tract. And remember,  

extrapyramidal fibers are responsible for fine  coordination of movements and support voluntary  

movements, they make our voluntary movements  more precise. SO that is the rubrospinal tract. 

The next tract is the tectospinal tract. It  transmits motor impulses for the eyes and  

neck muscles. So they coordinate the eyes and  the neck muscles when you look at something.  

Imagine you’re looking at a hamburher, you look  at it, and you keep looking at it as it passes you  

and your neck muscles follow your eyes. That’s  what this tectospinal tract is responsible for.  

It’s called tectospinal tract because it comes  from the tectum of the midbrain, it’s located  

on the posterior surface of the midbrain.  It’s also extrapyramidal, so it unconsciously  

moves your neck muscles with your eyes. Then we have the Reticulospinal Tract.  

We have a lateral Reticulospinal tarct, and a  medial reticulospnal tract, which are also a  

part fo the balance and posture system. They come  from the reticular formation inside the brainstem.  

The Reticular system are responsible for  Sleep, alertness, cardiovascular control,  

breathing and all of those vital things. But  they’re also responsible for motor control  

like your balance and posture, through the  reticulospinal tract. So that is all of these. 

Let’s just clean up the labels and add  a little colour to differentiate them.  

There is one more tract that we need to mention,  which is the medial longitudinal fascicle,  

which descend and is present only in the cervical  segments, which coordinated involuntary movements  

of the head, neck, and eyes through  synapses between the cranial nerves 3,  

4, 6, and 11. So that was all I had for the  internal surface of the grey and the white matter. 

I made this table for the nuclei in the grey  matter and the tracts in the white matter we  

just went through, 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 3, what is the name of number  4, where does number 6 go and where does number 11  

go. If you can do that, then you’ve grasped  the anatomy of the medulla oblongata fully.  

If you found this video helpful, please  put a like, comment, share, whatever  

you find convenient to you. The next video is going to be about the Pons