Medical School Question help please

[h2266]

Hi guys,
I just had a question which was was bugging me for quite a while.
I understand that a peripheral nerve can be motor, sensory or autonomic or all three etc..
I also understand that ramus is the same thing as branch. However, branch and root are two different things.

The attached images highlight my understanding as I have annotated them.

In the image below, the peripheral skin nerve field is innervated by a peripheral/spinal nerve that is formed from the ventral branch of C5 spinal/peripheral nerve and dorsal branch of C6 spinal/peripheral nerve - and of course, in this case, the peripheral/ spinal nerve that is formed is purely a sensory peripheral nerve because it solely has fibres from the dorsal spinal/peripheral roots of C6 and C5. Dorsal spinal/peripheral roots only contain sensory fibres.

I am not sure if I am making much sense or if what I've mentioned above is correctly put. Also, I guess peripheral and spinal mean exactly the same thing, hence the peripheral/spinal but then again I might be wrong.

Could someone please kindly shed some light into this? Would mean a lot!! Thank you so much!

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[libertyyne]

What is your question.

 

[h2266]

What is your question.

Sorry about muddling everything up! I'll try again - I've shortened everything.
My question is: What is wrong with what I have written below and the image I have attached below? What are the mistakes?

A peripheral nerve can be motor, sensory or autonomic or all three etc..
Ramus is the same thing as branch. However, branch and root are two different things.
Peripheral and spinal mean exactly the same thing.
In the image below, the peripheral skin nerve field is innervated by a peripheral/spinal nerve that is formed from the ventral branch of C5 spinal/peripheral nerve and dorsal branch of C6 spinal/peripheral nerve - and of course, in this case, the peripheral/ spinal nerve that is formed is purely a sensory peripheral nerve because it solely has fibres from the dorsal spinal/peripheral roots of C6 and C5. Dorsal spinal/peripheral roots only contain sensory fibres.

 

[stickgirl390]

It is my understanding that the light blue portion you have labeled “C5 spinal/peripheral nerve” is the only point where it is proper to use the term “spinal nerve”. There are only ~30 spinal nerves in the body. Using the term “spinal nerve” refers to the point where the ventral and dorsal roots join together, thus mixing motor and sensory nerve fibers. Once the spinal nerve splits into posterior and anterior rami, you shouldn’t use the term “spinal nerve” any more.

 

[TelemarketingEnigma]

I think you've also got some confusion about the dorsal/ventral rami. If that's what you're trying to understand, the picture you chose to focus on probably isn't the best diagram for that - I think that is a simplified diagram that is only showing the ventral branches/rami, to make a point about dermatomes vs. nerve fields. the dorsal rami of the spinal nerves (which I'm pretty sure just aren't shown at all in the image) innervate the back, while the ventral rami innervate the anterolateral trunk and limbs.

 

[stickgirl390]

I second what @TelemarketingEnigma said. This image that you posted is better:

 

[GoSpursGo]

We've gotten a couple of reports about this thread being homework help. As close as I can tell, that's not what this is, but rather just discussing medical concepts among other medical students. That's allowed.

 

[h2266]

It is my understanding that the light blue portion you have labeled “C5 spinal/peripheral nerve” is the only point where it is proper to use the term “spinal nerve”. There are only ~30 spinal nerves in the body. Using the term “spinal nerve” refers to the point where the ventral and dorsal roots join together, thus mixing motor and sensory nerve fibers. Once the spinal nerve splits into posterior and anterior rami, you shouldn’t use the term “spinal nerve” any more.

I think you've also got some confusion about the dorsal/ventral rami. If that's what you're trying to understand, the picture you chose to focus on probably isn't the best diagram for that - I think that is a simplified diagram that is only showing the ventral branches/rami, to make a point about dermatomes vs. nerve fields. the dorsal rami of the spinal nerves (which I'm pretty sure just aren't shown at all in the image) innervate the back, while the ventral rami innervate the anterolateral trunk and limbs.

Ah thank you so much guys!! I really appreciate your help!

 

[h2266]

We've gotten a couple of reports about this thread being homework help. As close as I can tell, that's not what this is, but rather just discussing medical concepts among other medical students. That's allowed.

Hi! Sorry about that - I thought you were allowed to ask questions about topics covered in medical school.

Is there a website for medical school study help by any chance? I can't really find any

Thanks!

 

[GoSpursGo]

Hi! Sorry about that - I thought you were allowed to ask questions about topics covered in medical school.

Is there a website for medical school study help by any chance? I can't really find any

Thanks!

I think you misread my post--these kinds of questions ARE allowed

Homework help is more like, "Here are the five questions on my biochem homework tonight, can anyone tell me the answers?" Questions like yours, which are more about general concepts, are fine, and honestly I'd like to see more discussions like this.

 

[h2266]

I think you misread my post--these kinds of questions ARE allowed

Homework help is more like, "Here are the five questions on my biochem homework tonight, can anyone tell me the answers?" Questions like yours, which are more about general concepts, are fine, and honestly I'd like to see more discussions like this.

Ah thanks so much! I definitely misread your post and then started panicking haha!

 

[h2266]

It is my understanding that the light blue portion you have labeled “C5 spinal/peripheral nerve” is the only point where it is proper to use the term “spinal nerve”. There are only ~30 spinal nerves in the body. Using the term “spinal nerve” refers to the point where the ventral and dorsal roots join together, thus mixing motor and sensory nerve fibers. Once the spinal nerve splits into posterior and anterior rami, you shouldn’t use the term “spinal nerve” any more.

I think you've also got some confusion about the dorsal/ventral rami. If that's what you're trying to understand, the picture you chose to focus on probably isn't the best diagram for that - I think that is a simplified diagram that is only showing the ventral branches/rami, to make a point about dermatomes vs. nerve fields. the dorsal rami of the spinal nerves (which I'm pretty sure just aren't shown at all in the image) innervate the back, while the ventral rami innervate the anterolateral trunk and limbs.

I second what @TelemarketingEnigma said. This image that you posted is better:

View attachment 273657

Hey guys, so sorry just need to ask these questions also,.. otherwise I might lose some brain cells thinking about them.

What is correct, below?
A spinal nerve gives many ventral branches and many dorsal branches as shown in the image I have annotated and highlighted below. However, in the black and white image below, a spinal nerve gives only one ventral branch and one dorsal branch. (2 contradictory points)

Also, which of the following below would be possible? ( I couldn't think of any other scenarios in which a peripheral nerve is formed other than the ones below)
A ventral branch from one spinal nerve joins with a ventral branch from another spinal nerve to form a peripheral nerve.
A dorsal branch from one spinal nerve joins with a dorsal branch from another spinal nerve to form a peripheral nerve.
A dorsal branch from one spinal nerve joins with a ventral branch from another spinal nerve to form a peripheral nerve.
Many ventral branches from one spinal nerve joins with many ventral branches from another spinal nerve to form a peripheral nerve.
Many dorsal branches from one spinal nerve joins with many dorsal branches from another spinal nerve to form a peripheral nerve.
Many dorsal branches from one spinal nerve joins with many ventral branches from another spinal nerve to form a peripheral nerve.

Also, how do you know that the dorsal branches of the spinal nerves are not shown in the image (the image with my annotations)? How do you know that only the ventral branches are shown?

Furthermore, is the image attached below now correct (I have changed the annotations)?

Thank you so much! Hate asking questions tbh (feel like a right idiot) but if I don't, it will drive me crazy lol :/
Thanks again!!

 

[TelemarketingEnigma]

I’m probably not going to be able to tackle everything you’re wondering about right now since I’m on my phone, but I’m also bored in a waiting room so hopefully can help clear up a few things

First, “peripheral nerve” really just means any nerve outside the central nervous system (brain+spinal cord), it’s not a specific type of nerve. So peripheral nerve is actually an umbrella term that includes spinal nerves (but it doesn’t work the other way around, so you can’t just call any peripheral nerve a spinal nerve).

The dorsal ramus from a given spinal root will usually travel backwards, and split into several branches that innervate different muscles or areas of the back.

The ventral ramus will give off branches as well. Depending on where you are in the spinal column, these branches can do different things. Some will travel independently to whatever muscle/area of skin/organ they are innervating. Some will join up with branches from other spinal nerves to form larger nerves, that carry nerve fibers originating from multiple levels of the spinal column. These larger nerves might split again later into smaller nerves. Basically this results in a network of nerves connected in various complicated ways, called a “plexus”

You can tell that the picture you’re using is a simplified diagram because it’s also missing other structures (like the sympathetic ganglia). And you can tell these are ventral rami and not dorsal because tbh we care about ventral rami more - they contribute to the various plexuses you’ll spend a bunch of time trying to commit to memory (I get the sense from your questions that you haven’t started working on things like the brachial plexus yet)

From your new annotations, I wouldn’t put the ventral branch labels on it like that. The dorsal/ventral split would have occurred earlier than where you’ve labeled it (somewhere in your light blue region), and everything downstream is all from the ventral ramus.

Editing to add since I just looked again at your post: each spinal nerve gives off just one ventral ramus and one dorsal ramus. However, each of these rami can give off lots of different branches of their own, which become the bane of every med students existence who has taken anatomy and had to learn all these nerves/branches/plexuses/clumps of spaghetti

 

[h2266]

I’m probably not going to be able to tackle everything you’re wondering about right now since I’m on my phone, but I’m also bored in a waiting room so hopefully can help clear up a few things

First, “peripheral nerve” really just means any nerve outside the central nervous system (brain+spinal cord), it’s not a specific type of nerve. So peripheral nerve is actually an umbrella term that includes spinal nerves (but it doesn’t work the other way around, so you can’t just call any peripheral nerve a spinal nerve).

The dorsal ramus from a given spinal root will usually travel backwards, and split into several branches that innervate different muscles or areas of the back.

The ventral ramus will give off branches as well. Depending on where you are in the spinal column, these branches can do different things. Some will travel independently to whatever muscle/area of skin/organ they are innervating. Some will join up with branches from other spinal nerves to form larger nerves, that carry nerve fibers originating from multiple levels of the spinal column. These larger nerves might split again later into smaller nerves. Basically this results in a network of nerves connected in various complicated ways, called a “plexus”

You can tell that the picture you’re using is a simplified diagram because it’s also missing other structures (like the sympathetic ganglia). And you can tell these are ventral rami and not dorsal because tbh we care about ventral rami more - they contribute to the various plexuses you’ll spend a bunch of time trying to commit to memory (I get the sense from your questions that you haven’t started working on things like the brachial plexus yet)

From your new annotations, I wouldn’t put the ventral branch labels on it like that. The dorsal/ventral split would have occurred earlier than where you’ve labeled it (somewhere in your light blue region), and everything downstream is all from the ventral ramus.

Editing to add since I just looked again at your post: each spinal nerve gives off just one ventral ramus and one dorsal ramus. However, each of these rami can give off lots of different branches of their own, which become the bane of every med students existence who has taken anatomy and had to learn all these nerves/branches/plexuses/clumps of spaghetti

Oh wow! Thank you so much! You are a lifesaver!

 

[h2266]

I’m probably not going to be able to tackle everything you’re wondering about right now since I’m on my phone, but I’m also bored in a waiting room so hopefully can help clear up a few things

First, “peripheral nerve” really just means any nerve outside the central nervous system (brain+spinal cord), it’s not a specific type of nerve. So peripheral nerve is actually an umbrella term that includes spinal nerves (but it doesn’t work the other way around, so you can’t just call any peripheral nerve a spinal nerve).

The dorsal ramus from a given spinal root will usually travel backwards, and split into several branches that innervate different muscles or areas of the back.

The ventral ramus will give off branches as well. Depending on where you are in the spinal column, these branches can do different things. Some will travel independently to whatever muscle/area of skin/organ they are innervating. Some will join up with branches from other spinal nerves to form larger nerves, that carry nerve fibers originating from multiple levels of the spinal column. These larger nerves might split again later into smaller nerves. Basically this results in a network of nerves connected in various complicated ways, called a “plexus”

You can tell that the picture you’re using is a simplified diagram because it’s also missing other structures (like the sympathetic ganglia). And you can tell these are ventral rami and not dorsal because tbh we care about ventral rami more - they contribute to the various plexuses you’ll spend a bunch of time trying to commit to memory (I get the sense from your questions that you haven’t started working on things like the brachial plexus yet)

From your new annotations, I wouldn’t put the ventral branch labels on it like that. The dorsal/ventral split would have occurred earlier than where you’ve labeled it (somewhere in your light blue region), and everything downstream is all from the ventral ramus.

Editing to add since I just looked again at your post: each spinal nerve gives off just one ventral ramus and one dorsal ramus. However, each of these rami can give off lots of different branches of their own, which become the bane of every med students existence who has taken anatomy and had to learn all these nerves/branches/plexuses/clumps of spaghetti

Thanks so much for the edit You just answered what was in my mind a few moments ago before your edit haha!