Internal Spinal Cord (Gray Matter, White Matter, Funiculus) - Anatomy

Summary

In this educational video, the host delves into the anatomy of the Central Nervous System, focusing on the internal structure of the Spinal Cord. The discussion covers the distribution of grey and white matter, detailing the functions of key nuclei within the grey matter and the tracts within the white matter. The video explains the roles of these components in processing sensory information and initiating motor responses, distinguishing between conscious and unconscious pathways. It also touches on the significance of the spinal cord's sympathetic and parasympathetic segments. A quiz is provided at the end to test viewers' understanding.

Takeaways

• 🧠 The Central Nervous System (CNS) is composed of the encephalon and the spinal cord.
• 🔎 The internal surface of the spinal cord is divided into grey and white matter, with the grey matter containing cell bodies and dendrites, and the white matter containing myelinated axons and glial cells.
• 🏓 The grey matter is structured into three horns: anterior, posterior, and lateral horns, each with specific functions related to motor and sensory activities.
• 🧪 The central canal within the spinal cord is filled with cerebrospinal fluid and lined by ependymal cells.
• 🌐 The anterior horn primarily contains motor nuclei, whose axons form the motor root of the spinal nerve.
• 🔍 The posterior horn is associated with sensory information, housing several nuclei that process different types of sensory data.
• 🔄 The intermediate zone contains nuclei that are involved in proprioception and are situated between the anterior and posterior horns.
• 📏 The lateral horn, present in specific spinal cord segments, contains nuclei related to the sympathetic and parasympathetic nervous systems.
• 🧵 The white matter is divided into three funiculi (posterior, lateral, and anterior), each containing different tracts responsible for ascending and descending signals.
• 🔺 Ascending tracts in the spinal cord convey sensory information to the brain, while descending tracts transmit motor commands from the brain to the body.

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 difference between grey matter and white matter in the spinal cord?

Grey matter consists of nerve tissue rich in nerve cell bodies and dendrites, while white matter consists of nerve tissue rich in myelinated axons and glial cells.

Why are myelinated axons in the white matter considered white?

Myelinated axons are white because they are rich in lipids, which are white in color.

What are the three horns of the grey matter in the spinal cord?

The grey matter consists of an anterior horn, a posterior horn, and a lateral horn.

What is the function of the anterior horn in the spinal cord?

The anterior horn primarily consists of motor nuclei whose axons leave the spinal cord as the motor root of the spinal nerve.

What type of sensory information is processed in the posterior horn of the spinal cord?

The posterior horn is associated with receiving sensory information, including pain, touch, and temperature.

What is the function of the central canal in the spinal cord?

The central canal is filled with cerebrospinal fluid and is lined by ependymal cells, serving as a pathway for the fluid within the spinal cord.

How are the tracts within the white matter of the spinal cord organized?

The tracts are organized into ascending (afferent) and descending (efferent) tracts, which further divide into conscious and unconscious sensory information tracts, and involuntary and voluntary movement tracts.

What are the two types of sensory information carried by the ascending tracts in the spinal cord?

The ascending tracts carry both conscious sensory information, which goes to the cortex of the cerebrum, and unconscious sensory information, which goes to the cerebellum.

What is the role of the corticospinal tracts in the spinal cord?

The corticospinal tracts, which include the anterior and lateral corticospinal tracts, are responsible for voluntary movements and originate from the pyramidal cells of the primary motor cortex.

Outlines

00:00

🧠 Introduction to the Central Nervous System

The video script introduces the anatomy of the Central Nervous System (CNS), focusing on the internal structure of the spinal cord. It outlines the CNS's two main parts, the encephalon and the spinal cord, and emphasizes the importance of understanding the spinal cord's internal surface, including the distribution of grey and white matter. The grey matter, rich in nerve cell bodies and dendrites, is contrasted with the white matter, rich in myelinated axons and glial cells. The script also mentions a quiz at the end of the video to test the viewer's understanding, and it references a previous video that covered the external structures of the spinal cord.

05:01

🌐 Detailed Anatomy of the Spinal Cord's Grey Matter

This section delves into the anatomy of the spinal cord's grey matter, which is divided into three horns: anterior, posterior, and lateral. The anterior horn contains motor nuclei, while the posterior horn is associated with sensory information processing. The lateral horn, found between specific spinal segments, is involved with sympathetic and parasympathetic fibers. The intermediate column and central zone are also described, with the central canal filled with cerebrospinal fluid. The grey matter contains various nuclei, including the marginal nucleus, the gelatinous substance, the nucleus proprius, and the posterior thoracic nucleus, each with specific roles in processing sensory information.

10:04

🔄 Functions of the Spinal Cord's White Matter

The white matter of the spinal cord is composed of myelinated axons and is divided into the posterior, lateral, and anterior funiculi. The script explains the general arrangement of nerve fibers within the white matter, which can be ascending (afferent) or descending (efferent) tracts. Ascending tracts are further divided into those carrying unconscious sensory information to the cerebellum and those carrying conscious sensory information to the cerebral cortex. Descending tracts are categorized into voluntary movements, which originate from the primary motor cortex, and involuntary movements, which originate from other parts of the brain.

15:10

🚶‍♂️ Sensory and Motor Tracts in the Spinal Cord

This part of the script describes the specific sensory and motor tracts within the spinal cord. The posterior funiculus contains the fasciculus gracilis and fasciculus cuneatus, which are responsible for conscious proprioception and mechanoreception from the lower and upper body, respectively. The lateral and anterior funiculi house the spinocerebellar tracts, which provide unconscious proprioception to the cerebellum. The spinothalamic tracts in these funiculi are responsible for conscious sensations of pain, temperature, pressure, and touch. The script also covers motor tracts, including the corticospinal tracts, which are involved in voluntary movements, and extrapyramidal tracts like the rubrospinal, tectospinal, and olivospinal tracts, which support balance, posture, and coordination.

20:16

🔚 Review and Anticipation of Upcoming Content

The final section of the script reviews the nuclei and tracts discussed in the video and challenges the viewer to recall the names and functions of these structures without visual aids. It also provides a table summarizing the information for both the grey and white matter of the spinal cord. The script concludes with a call to action for viewers to engage with the video and an announcement of the next topic, which will be the medulla oblongata.

Keywords

💡Central Nervous System (CNS)

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 the video's theme as it is the main focus of the anatomy discussion. The CNS is responsible for processing and coordinating most of the nervous system's activities, including thinking, learning, and controlling bodily movement. In the script, the CNS is divided into two parts: the encephalon (brain) and the spinal cord, setting the stage for the detailed exploration of the spinal cord's internal surface.

💡Spinal Cord

The spinal cord is a central component of the CNS, discussed extensively in the video. It is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata to the lumbar vertebrae. The video script delves into the spinal cord's internal surface, highlighting the distribution of grey and white matter, which are essential for its function in transmitting signals between the brain and the rest of the body.

💡Grey Matter

Grey matter in the spinal cord consists of nerve cell bodies and dendrites. It is referred to as 'grey' because it appears greyish when viewed under a microscope without staining. The script mentions that grey matter is rich in nerve tissue and is organized into horns, including anterior, posterior, and lateral horns. These areas are crucial for processing sensory information and initiating motor responses.

💡White Matter

White matter in the spinal cord is composed mainly of myelinated axons and glial cells, which give it a whitish appearance due to the high lipid content in myelin. The video script describes how white matter is organized into tracts or bundles of fibers that facilitate communication between different parts of the nervous system. These tracts are categorized as either ascending (carrying information to the brain) or descending (carrying information from the brain).

💡Nuclei

Nuclei are clusters of neuron cell bodies located in the grey matter of the spinal cord. They are essential for processing and relaying information. The script explains various nuclei, such as the marginal nucleus, gelatinous substance, and nucleus proprius, each playing a distinct role in sensory processing. Understanding these nuclei is key to grasping the video's discussion on the spinal cord's functionality.

💡Tracts

Tracts refer to the bundles of nerve fibers (axons) found in the white matter of the spinal cord. They are responsible for传导 nerve impulses. The video script describes different types of tracts, including ascending sensory tracts like the spinothalamic tracts and descending motor tracts like the corticospinal tracts, which are vital for the spinal cord's role in transmitting sensory information to the brain and motor commands from the brain to the muscles.

💡Axons

Axons are long, slender projections of a nerve cell that conduct electrical impulses away from the neuron's cell body. They are a critical component of white matter, as highlighted in the script. Myelinated axons, in particular, are emphasized for their high lipid content, which contributes to the white appearance of white matter. Axons facilitate communication within the CNS, playing a central role in the video's exploration of the spinal cord's anatomy.

💡Spinal Nerves

Spinal nerves are nerves that originate from the spinal cord and branch out to supply various parts of the body. The video script touches on the anatomy of spinal nerves and their connection to the spinal cord. These nerves are essential for transmitting sensory information to the spinal cord and motor commands from the spinal cord to the muscles.

💡Reflex Arcs

Reflex arcs are neural pathways that mediate quick, automatic responses to stimuli. The script mentions two types of reflex arcs that occur through the spinal cord: unconscious and conscious proprioception. Unconscious reflex arcs are involved in automatic responses like posture and balance, while conscious reflex arcs involve sensory input that reaches the brain for processing.

💡Cerebrospinal Fluid (CSF)

Cerebrospinal fluid is a clear fluid that circulates around the brain and spinal cord, providing cushioning and buoyancy. The video script refers to the central canal of the spinal cord, which is filled with CSF, similar to the subarachnoid space. This fluid is vital for the health of the CNS and is an important aspect of the spinal cord's internal environment.

💡Ependymal Cells

Ependymal cells are a type of glial cell that line the ventricles of the brain and the central canal of the spinal cord. The script mentions these cells as forming a central gelatinous substance of the spinal cord. They play a role in producing and maintaining the cerebrospinal fluid, which is essential for the health and function of the CNS.

Highlights

Introduction to the anatomy of the Central Nervous System, focusing on the internal surface of the Spinal Cord.

Explanation of the distribution of white and grey matter within the Spinal Cord.

Description of grey matter composition, including nerve cell bodies and dendrites.

Discussion on why myelinated axons in white matter appear white due to their lipid content.

Identification of the three horns within the grey matter: anterior, posterior, and lateral horns.

Function of the anterior horn, primarily consisting of motor nuclei.

Role of the posterior horn in receiving sensory information and its associated nuclei.

Explanation of the intermediate zone and its nuclei related to proprioception.

Mention of the lateral horn and its association with sympathetic and parasympathetic fibers.

Description of the central zone and the central canal filled with cerebrospinal fluid.

Importance of the spinal reticular formation in regulating basic life functions.

Division of white matter into three funiculi: posterior, lateral, and anterior.

General arrangement of nerve fibers into ascending and descending tracts within the white matter.

Differentiation between conscious and unconscious sensory information in ascending tracts.

Description of the corticospinal tracts as part of voluntary movement control.

Role of extrapyramidal tracts in involuntary movements and posture.

Identification of specific sensory tracts in the posterior funiculus: Fasciculus Gracilis and Fasciculus Cuneatus.

Function of spinocerebellar tracts in providing unconscious proprioception.

Importance of spinothalamic tracts in conveying conscious sensations of pain, temperature, pressure, and touch.

Overview of the vestibulospinal tract's role in balance and posture.

Introduction to the reticulospinal tracts and their contribution to motor control.

Conclusion and summary of the Spinal Cord's grey and white matter anatomy.

Transcripts

What’s up. Meditay Here.

Let’s talk about the  anatomy of the Central Nervous System.

In this segment, we will be talking about the Internal  surface of the Spinal Cord. Basically go through  

everything you need to know regarding the anatomy  of the tracts and nuclei within the spinal Cord. 

Alright, so the Central Nervous System consists  of two parts. The encephalon and the spinal Cord 

So in this is video, we’re first going to go  through the internal surface of the Spinal Cord  

and talk about the distribution of white and grey  matter within it. Then we’ll look detailed into  

the anatomy of the grey matter and the anatomy of  the white matter. Then at the end of this video,  

I’ve made a quiz which you’ll hopefully  be able to pass based on this video.  

In our previous video, we looked at the Topography  and the external structures of the Spinal Cord,  

as well as the anatomy of the spinal nerve  and the two types of reflex arches we have  

through the spinal Cord. So if this is the  first time you’re studying the spinal Cord,  

I recommend you to watch that first because this  video will make much more sense with you knowing  

the external surface of the Spinal Cord. Alright. We can start by taking a small  

segment of the spinal Cord, and look at  its internal surface. It’ll look like this. 

The internal surface of the Spinal Cord consists  of grey matter and white matter. The reason why  

they’re called grey and white matter is because  if you look at a neuron. A neuron is colorless in  

general. And we know that because if you cut the  spinal Cord physically and look at it underneath  

the microscope without any significant staining,  you’ll see that the neurons are grey. So the grey  

matter consists of nerve tissue rich in nerve  cell bodies and dendrites. White matter consists  

of nerve tissue rich in myelinated axons and  glial cells, as you see here. And the reason why  

myelinated axons are white is because they’re  rich in lipid, and lipids are white. And keep  

this in mind throughout this video because you’ll  notice as we go through the structures in the grey  

matter, we’ll be talking about nuclei or nucleus  because cell bodies are in the grey matter.  

When we’re talking about the white matter, we  have structures called tracts, which are axons. 

So let’s start with the grey matter first.  The grey matter consists of three horns. We  

have an anterior horn and a posterior horn, or  conu anterius and conu posterius. And where is  

the last horn? The last horn is located in the  spinal segments associated with the sympathetic  

and the parasympathetic fibers, between the  C8 and L2, and S2 and S4 spinal cord segments.  

So if you cut the spinal Cord within those  areas, you’ll see that we have an anterior horn,  

a posterior horn, and a lateral horn  that give off either sympathetic fibers  

or parasympathetic fibers. So this segment  is from an area outside of the sympathetic or  

parasympathetic segments. -- 

Between the anterior and posterior horn, there’s  the Intermediate column. Then in the middle,  

there’s the Central Zone, with the central canal  in the middle. The central canal is filled with  

cerebrospinal fluid, which is the same fluid as in  the subarachnoid space. Around the central canal,  

there are cells called ependymal cells, forming a  central gelatinous substance of the Spinal Cord,  

which is the same lining as the rest  of the ventricles in the spinal Cord. 

So now I wanna focus on each of these  zones, basically go through the most  

important nuclei you’ll find, and  we’ll start with the Anterior horn. 

So the anterior horn is pretty easy as  it primarily consists of motor nuclei.  

Their axons leave the spinal Cord as  the motor root of the spinal nerve. 

So that’s mostly it for the anterior horn. The  posterior horn is associated with receiving  

sensory information. You’ll notice that it  consists of several nuclei responsible for  

certain types of sensory information. So the  first one is the marginal nucleus consisting  

of interneurons triggered by any sensory neuron  coming into the spinal Cord. Then there’s the  

gelatinous substance, which also consists  of interneurons that modulate sensory input 

Then there’s the Nucleus Proprius, which consists  of neurons that modulate sensory input like pain,  

touch, and temperature. They take the information  and send them upwards to the higher senses 

After that, we have the posterior thoracic  nucleus, which receives unconscious proprioceptive  

movement. Basically giving information  about the position and posture of the body.  

So that was the posterior horn. Now let’s do the intermediate zone. And the first  

nucleus here is the intermediomedial nucleus since  it’s located medially within the grey matter.  

This nucleus has more or less the same  function as the posterior thoracic nucleus,  

which is unconscious proprioception. And some  sources consider the posterior thoracic nucleus  

as a part of the intermediate zone,  not a part of the posterior horn,  

so keep that in mind. But there are two  more nuclei within the intermediate zone,  

and they’re located within the lateral  horn. Remember we mentioned this earlier? 

So in the lateral horn, we’ll find two different  nuclei depending on where we are within the spinal  

Cord. If we’re between spinal segments C8 through  L2, then we have the IntermedioLateral nucleus,  

which consists of sympathetic fibers for the  fight or flight response. They will send their  

fibers together with the motor fibers down  through the anterior root of the spinal nerve. 

If we’re looking at a segment between S2 and S4,  we will see the Sacral Parasympathetic nuclei,  

which also send their fibers through  the anterior root of the spinal nerve,  

responsible for the rest and  digest state of the person. 

So the intermediate column consists of the  Intermediomedial nucleus, Intermediolateral  

nucleus, Sacral parasympathetic nucleus, and the  posterior thoracic nucleus if your sources say so. 

Alright, so now we’ve covered the majority of  nuclei within all three zones of the grey matter. 

Along the outer part of the grey matter, you’ll  find a very thin layer of white matter called  

fasciculi proprii, which are fibers that  connect adjacent parts of the grey matter  

together or adjacent segments because you can  also divide the grey matter into segments. 

Another thing you’ll find is grey matter  that is pressed into the white matter called  

spinal reticular formation, or Formatio  retucularis spinalis, which continues  

upwards into the brainstem. It consists of  neurons that make a communicative network for  

activating certain sensory information for basic  living. So it regulates respiration, heartbeat,  

blood pressure, and all of those things. Here’s maybe a better representation of the  

spinal reticular formation, and again  it goes upwards into the brainstem. 

So that was all for the grey matter of the  Spinal Cord, now let’s do the white matter. 

The white matter of the Spinal Cord, remember  its nerve tissue rich in myelinated axons,  

so we’re not talking about nucleus anymore.  We’re talking about tracts or bundles of fibers. 

And the white matter is divided into three  portions because you’ll find connective  

tissue separating these three portions. We have  the Posterior Funiculus, the Lateral funiculus  

and the Anterior funiculus. So again, these  funiculi are bundles of fibers that are  

surrounded by connective tissue. Now before  we go detailed into each of these funiculi.  

I wanna spend a little bit of time  explaining the general arrangement of fibers  

within the white matter. And by understanding  that, the tracts will get much more logical. 

Alright, so nerve fibers are  arranged in bundles or tracts, right? 

So here are many neurons. There are  connective tissue around all of those neurons,  

and that was what we call a tract. And there are  three .. um.. directions these tracts can go. 

They can either go upwards, as ascending tracts,  

or afferent tracts, remember a stands for  arrive, so these tracts arrive to the brain,  

but they can also descend, go down as descending  tracts, or efferent tracts e stands for exit. 

So the asceding tracts receive sensory  information from anywhere in the body,  

and send them up to your higher senses to make  sense out of them. And then once you’ve done that,  

you’d wanna react to the sensory information,  or you just wanna move a muscle in general,  

so you activate the descending tracts. So you accidentally put your hand above  

something hot, sensory information is sent  up, and then you react by descending tracts  

activating muscles to remove your hand. And  again, all of that happens through funiculi, which  

means long ropes, found within the posterior,  lateral, and anterior parts of the Spinal Cord. 

The ascending and descending tracts  can further be divided into two parts. 

The ascending tracts are generally divided into  unconscious and conscious sensory information.  

Now, what is the difference? Well, everything  that goes to the cortex of your cerebrum  

is considered conscious. Unconscious sensory  input goes to the cerebellum. The cerebellum is  

an organ responsible for balance and posture, so  the unconscious ascending tract relays unconscious  

proprioceptive sensation. You’ll see this word a  lot as you study the tracts of the central nervous  

system. So it’s important that you have a general  knowledge about it. Unconscious proprioception is  

responsible for posture, meaning sensory  fibers from muscles are all the time sent  

to the cerebellum so that it can activating  the necessary muscles to keep your posture,  

as well as activating muscles that support your  joints and the natural position of your limbs,  

so information about joint stability is  considered unconscious proprioception as well.  

But there is one more thing. Imagine you’re  outside, walking and minding your own business. 

All of a sudden, YOU SEE A CAR DRIVING  TOWARDS YOU AND BREAKS RIGHT IN FRONT OF YOU.  

Your initial response is tensing your  muscles, a process called feedforward control.  

Your muscles tenses due to something in the  external environment. And in the majority of  

times, you’re not in control of it, and we  consider this as unconscious proprioception  

as well. They’re unconscious because they go to  the cerebellum, which is this organ right here.

In our spinal Cord, we have tracts called  the anterior spinocerebellar tract and the  

lateral spinocerebellar tract. They end with the  word cerebellar, so they go to the cerebellum. 

Conscious sensory information relays conscious  proprioception, like kinesia, which is conscious  

muscle movement. The conscious joint position  is considered a part of this system, as well as  

a sense of force. Meaning as your standing,  you consciously know that there’s a force  

acting against you, which is the floor against  your feet. The conscious sensory information  

is also responsible for sensing certain things,  like touch, and pain and pressure and temperature. 

Examples of conscious ascending tracts are  the anterior and lateral spinothalamic tracts,  

the cuneate, and the gracilis fascicle, which send  their information to the cortex of the cerebrum. 

So that is the ascending tracts, but we also  divide the descending tracts into two parts.  

We divide it into Involuntary  movements and voluntary movements. 

So one of the important parts of our cerebral  cortex is the primary motor cortex. If we look  

at it underneath the microscope, you’ll  find that it consists of pyramidal cells. 

They’re pyramidal because they literally  look like pyramids. So when you decided you  

wanted to click on this video or search for the  internal surface of the Spinal Cord on youtube,  

you activated the pyramidal cells  to give the command to your muscles.  

All the tracts that come from the pyramidal  cells are called voluntary movements. And  

they help you make fine conscious movements like  when you’re writing with a pen. These movements  

are so precise that they make your handwriting  look good. These tracts usually start with the  

name Cortico- Like the anterior corticospinal  tract and the lateral corticospinal tract. 

When motor fibers doesn’t  come from the pyramidal cells,  

they’re called extrapyramidal tracts meaning these  tracts originate from other parts of your brain  

instead of the primary motor cortex So these movements are movements you  

don’t really think about, like keeping your  balance and posture when you’re walking, as  

well as rough movements or coarse movements. These  tracts doesn’t come from the primary motor cortex,  

so they have other names like rubrospinal  tract, tectospinal tract and olivospinal tracts. 

So I hope this made a little sense to you  all because once you’ve visualized this part.  

The next part of this video will  be much easier to understand.

So let’s now start by talking about the  tracts within each of these funiculi,  

and we’ll start with the posterior one. Ok, so in this diagram, I’ve made the blue  

colors represent sensory fibers and the  red ones representing motor fibers. The  

posterior funiculus has two sensory tracts.  The first one is called Fasciculus Gracilis.  

This tract will conduct impulses from the  lower part of the trunk and the lower limbs,  

so it’s present in all the segments of the Spinal  Cord, and it takes the information to the cortex.  

And since it brings info to the cortex, then  remember its function is conscious sensation.  

In this case, it’s responsible for the epicritic  sensibility of the lower parts of the body.  

Epicritic sensibility means Conscious  proprioception, which remember is Kinesia,  

joint position, and sense of force. But epicritic sensibility also means receiving  

info from the mechanoreceptors. Now, what does  that mean? It senses two-point discrimination,  

so the minimal distance between two  touchpoints, until you actually sense  

that there are two objects touching you, that is  the two points discrimination. Mechanoreceptors  

also sense vibration and touch. So all of those  things are what we call epicritic sensibility. 

The other ascending tract of the posterior  funiculus is the Fasciculus Cuneatus, which brings  

sensory information from the upper body and sends  it to the cortex. So it does exactly the same as  

Fasciculus Gracilis, just for the upper body.  And since this tract si only for the upper body,  

you’ll find this tract only above the thoracic  spinal segment number 6. So that was all of the  

posterior funiculus. Fasciculus Gracilis for lower  limb and Fasciclus Cuneatus for Upper limb. I use  

the letter G in Gracilis as Genitals to remember  that gracilis is for the lower part of the body 

Next, Let’s do the Lateral and the anterior  funiculus together because you’ll find tracts  

that do the same but are present on both  the lateral and the anterior funiculus. 

Just remember that they’re divided by  connective tissue. These two funiculi are  

divided by connective tissue, and we’ll represent  the connective tissue using these two brown lines. 

The first tracts are ascending tracts  located on the lateral funiculus,  

called the SpinoCerebellar tracts. We have  two, there’s the anterior spinocerebellar tract  

and the posterior spinocerebellar  tract. Before ascending up,  

the posterior spinocerebellar tract receives  sensory input from the posterior thoracic nucleus,  

and the anterior spinocerebellar tract receives  sensory input from the intermediomedial nucleus. 

They then ascend to the cerebellum because they  both end with the word cerebellum. And remember,  

if something ascends to the cerebellum and not  the cerebral cortex. Then they provide unconscious  

proprioception, which later will provide  unconscious contraction of muscles for posture,  

joint stability, and the feedforward control  system. So that is the spinocerebellar tract.

Next, we have the spinothalamic tracts,  

and there are two spinothalamic tracts in our  spinal Cord. There’s the anterior spinothalamic  

tract in the anterior funiculus and a lateral  spinothalamic tract in the lateral funiculus.

These two tracts are formed by axons coming from  the nucleus proprius, and then they ascend to the  

cortex. And since they go to the cortex, they  are responsible for the conscious sensation of  

pain, temperature, pressure, and touch. So that  was all the sensory tracts of the Spinal Cord.  

Now let’s do the motor tracts  or the descending tracts.

This includes the corticospinal tracts.  We have two corticospinal tracts.  

There’s the Anterior corticospinal tract  in the anterior funiculus and the lateral  

corticospinal tracts in the lateral funiculus These tracts start with the name ‘’Cortico’’,  

meaning they come from the pyramidal  cells of the primary motor cortex.  

So they are pyramidal tracts. Now the Lateral and Anterior corticospinal  

tracts descend differently, but they both synapse  with the motor nuclei to stimulate the motor  

fibers in the anterior root of the spinal nerve. Alright. So the Lateral Corticospinal tract  

starts off at the cortex and then descend,  but they decussate at the medulla oblongata,  

meaning they cross to the other side as you  see here at the medulla oblongata, and form  

the decussation of pyramids, and then they descend  further as the lateral corticospinal tract in the  

spinal Cord and synapse with the motor nuclei. The Anterior corticospinal tract is a little bit  

different in that they descend without  crossing. Instead, they cross at each  

segment they’re going to leave from. So in this  example, if they’re gonna leave at this segment,  

they cross to the other side and synapse with  the motor nuclei. And since they come from  

the cortex, they’re responsible for conscious  movement. So that’s the corticospinal tracts 

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 fibers because they  originate from the red nucleus of the midbrain  

and go down as rubrospinal tract. And remember,  extrapyramidal tracts 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,  

located in the anterior funiculus. It transmits  motor impulses for the eyes and neck muscles  

meaning they coordinate the eyes  and the neck muscles when you look  

at something. I’ve animated this very badly, but  imagine you’re looking at a hamburger, 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 he midbrain,  

which is on your brainstem, and then descend  down and synapse with the motor nuclei.  

It’s extrapyramidal, so it unconsciously  moved your neck muscles with your eyes. 

Next 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, whether your head is tilted upside down or  to the side, all of that is sensed and through  

nerves, 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.  

So if you’re running and trip on a rock and you’re  about to fall, your vestibular system, along with  

other systems, will quickly react to that and  quickly activate the necessary muscles in order  

for you to keep your balance. And this happens  involuntarily because this tract doesn’t come  

from your cortex. It comes from your brainstem. So that is the Vestibulospinal tract. Next,  

we have the olivospinal tract. The olivospinal  tract is also responsible for balance and posture. 

Inside of your medulla oblongata, there  are olivary nuclei that send out fibers  

to the spinal Cord as the olivospinal tract,  which also synapse with the motor nuclei. Keep  

that in mind all motor tracts will synapse  with the motor nuclei of the grey mater. 

Then we have the Reticulospinal Tract.  We have a lateral Reticulospinal tract  

and a medial reticulospinal tract which are  also a part fo the balance and posture system.  

They come from the reticular  formation inside the brainstem  

and also from the reticular formation of  the Spinal Cord, remember we talked about  

that earlier? Just to remind you again. 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. Then lastly there’s  the medial longitudinal fascicle, located in the  

anterior fasciculus only in the cervical segments,  which coordinates involuntary movements of the  

head neck and eyes through synapses between  the cranial nerves. And then they’re going to  

synapse with the motor nuclei of the grey matter  as well. So that was all I had for the grey and  

the white matter of the spinal cord. So I made  this table for the nuclei in the grey matter 

And this is where this video  gets scary, I am going to make  

all of the names disappear. Now can you, from the  beginning, tell me what is the name of number 1,  

what is the name of number 2, and so on. And here is one for the white matter as well.  

You can pause the video if you want and have a  look, and then here is an empty table for you  

to fill. So that was everything I had for the  anatomy of the Spinal Cord. 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 Medulla Oblongata.