a

Neurology - Spinal Cord Introduction

automatically on biology and medicine

videos please make sure to subscribe

join the Foreman group for latest videos

please raise awareness again and hear

please like in this video we will talk

about the spinal cord we know the spinal

cord is part of the central nervous

system with the brain the spinal cord is

connected to the brainstem which then

connects the brain up on the top there

now the spinal cord is uniformly

organized and is divided into five

regions some people save for either way

on each of these regions have a number

of paired of spinal nerves coming out of

them so what I mean by this is for

example the first region of the spinal

cord is known as a cervical region and

this has eight pairs of spinal nerves

coming out so these red things there are

spinal nerves coming out eight pairs the

thoracic region has 12 pairs of spinal

nerves the lumbar region has five pairs

of spinal nerves the sacral region also

has five pairs of spinal nerves and

there is another region where we have

one pair of spinal nerves these nerves

are known as the coccygeal nerves

because they're sort of close to the cox

us spine of the spine so if we do our

awesome mathematics we can see that we

have 31 pairs of spinal nerves which

equates to 62 spinal nerves so each of

these regions of the spinal cord

each of these five regions of the spinal

cord are actually different in shape so

if we were to take a cross-section of

the cervical region here it would look

something like this but before we

continue on the person I draw on the

right we are looking at him from a

posterior view we're looking at his

spinal cord from a posterior view from

the back but the cross-sections of the

spinal cord I am

we're looking at it from an anterior

view so please know that the

cross-sections I'm drawing in spinal

cord now are we're looking at it from an

anterior view so anyway this is what a

cervical region of the spinal cord would

look like and here we have a pair of

spinal nerves attacked attaching to this

spinal cord the spinal nerve consists of

a ventral root the front root and a

dorsal root the back root which connects

to the spinal cord the spinal cord

itself consists of a gray matter in the

middle and white matter surrounding it

the hole in the center is known as the

central canal which contains

cerebrospinal fluid which helps in

nourishing the nervous tissue and we

should know what the grey and white

matter is because that's that was taught

in the previous neurology videos now if

we were complete to compare the cervical

region of the spinal cord to the

thoracic region of the spinal cord the

thoracic region would look a much

rounder in shape and remember we're

looking at it from an anterior view and

the lumbar region on the other hand

looks a bit like a more of a pyramid

shape not only that but the lumbar

region of the spinal cord has a much

thicker gray matter compared to the

other regions so as you can see the

regions of the spinal cord are all

different in shape and old to have

different thickness of the gray matter

for example but all of these regions

contain spinal nerves so let's just

learn a bit more about spinal nerves and

about its anatomy um the spinal nerves

which connect to the spinal cord is part

of the peripheral nervous system you can

say because it carries information

between the central nervous system and

periphery because it brings information

to the central nervous system to the

spinal cord and also takes information

from the central nervous system from the

spinal cord so let's just zoom into the

spinal nerve here to learn a bit more

about the anatomy so here we have the

spinal nerve the nerve is surrounded by

a membrane known as an epi neuro neom we

also find blood supply here and also

many bundles of neuron which make up

what's called a fascicle the fascicle if

we pull one out also consists of a

membrane called the peri

neuro Neum now as mentioned these

fascicles they contain many neurons

let's just pull one out here we have a

neuron which is surrounded by an endo

uranium another membrane this neuron

this neuron is also wrapped by Schwann

cells containing myelin and so this is a

myelinated axon of the neuron I hope

that makes sense and as we know

myelinated axons they generate faster

impulses so now that we know a bit more

about the spinal nerve let's just go

back to the spinal cord and look at what

sort of membranes if have and let's

learn a bit more about its anatomy by

doing this let's just take a

cross-section of the spinal cord of the

thoracic region now this spinal cord I'm

drawing which is part of the thoracic

region it can represent any any section

of the spinal cord but I'm just doing

this for simplicity because the spinal

cord is so important and it's part of

the central nervous system it of course

has to have some form of protection some

form of barrier and it does it has three

layers of protection from the most inner

membrane it has the pia mater then it

has the arachnoid membrane then it has

the dura mater and the

three make up what is known as the

meninges which serve as a protective

barrier of the central nervous system

against harmful things the central canal

the central canal which also contains

the cerebrospinal fluid also is a form

of protection for the spinal cord as the

cerebrospinal fluid also acts like a

shock absorber in the central nervous

system now back to the spinal cord

section coming out of each side of the

spinal cord region we have spinal nerves

right we know that to make this easier

we can draw a line here and say that the

spinal cord is part of the central

nervous system and the spinal nerves are

part of the peripheral nervous system

the spinal nerve that is part of the

peripheral nervous system consists of a

ventral root the front root and a dorsal

root the backward but both are connect

to the spinal cord and both also join up

with each other to form a big spinal

nerve the dorsal root containers also a

dorsal ganglion we can also have another

ganglion here which we will discuss

about later on ganglion is basically a

location where synopsis can occur and

also where where cell bodies are located

it's basically bundles of neurons but

anyway the dorsal root of the spinal

nerve is always for is always for

sensory neurons and these are where

sensory neurons are so sensory neurons

bring in sensory information to the

spinal cord via the dorsal root here and

then it will synapse with another neuron

in the central nervous system in the

spinal cord which will then which this

new neuron will then bring this sensory

information to the brain or the brain

stem or somewhere in the central nervous

system for processing for interpretation

so what I mean is that all sensory

neurons from the periphery such as this

sensory neuron I am drawing with myelin

wrapping around it this will receive

some form of sensory stimulation be a

touch pain pressure or whatnot

this will bring this sensory information

to the central nervous system through

the dorsal root of the spinal nerve the

sensory neurons body is located in the

dorsal ganglion here then the sensory

neuron will pass on the information to

the second neuron the second neuron will

then bring this sensory information to

the brain or brain stem for processing

for realizing that there is some sensory

information coming to to the body

now if the dorsal root is for sensory

neurons bringing in sensory information

to the central nervous system that means

the ventral root is for the efferent

neurons for the motor neurons so for

example signals or commands from the

brain or brain stem will come down to a

particular location in the spinal cord

and then these neurons will then sign

apps with efferent neurons here also

known as motor neurons which will bring

this command this information um

somewhere to a target tissue

now this efferent neuron this motor

neuron is actually a somatic neuron

which means that it is bringing

information or commands to initiate

movement so it's going to bring

information commands to skeletal muscle

for contraction for example and this

neuron therefore is voluntary because we

can control movement it is a somatic

neuron

ever there is another type of neuron um

another type of efferent neuron that can

bring information out of the central

nervous system this neuron will in red

will actually stop over in this ganglion

and synapse with another effort neuron

this efferent neuron is or motor neuron

is known as an autonomic neuron because

it is part of the autonomic nervous

system it is controlled involuntary it

will bring information or bring commands

from the central nervous system to our

tissues target cells and tissues such as

cardiac muscle cells smooth muscle cells

and certain glands or all glands because

we know how we have no control over

these types of cells now let's just look

at it as a summary we have the central

nervous system where we have the spinal

cord and within the spinal cord we have

neurons that carry sensory information

and also carry commands within the

spinal cord then we have the peripheral

nervous system which consists of two

types of neurons we have the sensory

neurons and we have the efferent neurons

also known as the motor neurons the

sensory neurons bring information to the

central nervous system whereas the

efferent neurons take information from

the central nervous system to a target

cell to a target tissue to the periphery

so here we're looking at the efferent

neurons so commands are information from

the central nervous system will travel

via efferent neurons efferent neurons

can be either somatic meaning that they

are voluntary or autonomic meaning that

they're involuntary and this all depends

on what a type of targets tissue or cell

it's going to

so I hope you enjoyed this video it's

only an introduction to the spinal cord

I'll have another video that will go

into a bit sort of a bit more detail and

it might be even easier than this one so

look forward to that and I'll probably

provide a link thank you for watching