Divisions of the Nervous System - Neuroanatomy Basics

Summary

In this Anatomy Zone tutorial, Peter explores the nervous system's organization, distinguishing between the central (CNS) and peripheral (PNS) divisions. The CNS, comprising the brain and spinal cord, processes environmental information. The PNS, including cranial and spinal nerves, transmits sensory data and motor responses. Peter further breaks down the CNS into the forebrain, midbrain, and hindbrain, detailing their development and functions. He also explains the autonomic nervous system, highlighting its parasympathetic, sympathetic, and enteric components, which regulate involuntary body functions. The tutorial concludes with a discussion on sensory and motor nerve fibers, essential for conscious perception and voluntary muscle control.

Takeaways

• 🧠 The nervous system is divided into the central nervous system (CNS) and the peripheral nervous system (PNS).
• 🌐 The CNS includes the brain and the spinal cord, which are responsible for complex information processing.
• 🔗 The PNS connects the CNS to peripheral structures through cranial and spinal nerves.
• 💧 Plexuses are networks of interconnected nerves that allow the redistribution of nerve fibers into different nerves.
• 🏢 Ganglia are collections of nerve cell bodies from the PNS, such as dorsal root ganglia and autonomic ganglia.
• 🧬 The brain can be broken down into the forebrain, midbrain, and hindbrain based on embryological development.
• 🧩 The hindbrain includes the medulla, pons, and cerebellum, each with specific functions.
• 🥼 The midbrain consists of the tectum and tegmentum, playing a role in visual and auditory reflexes.
• 🧠 The forebrain includes the telencephalon and diencephalon, which encompass the cerebral cortex and subcortical structures.
• 🔄 The PNS is divided into the somatic and autonomic nervous systems, with the latter further divided into parasympathetic, sympathetic, and enteric systems.
• 🔎 The autonomic nervous system is responsible for involuntary control of the body and maintaining homeostasis.
• 🏋️‍♂️ The somatic nervous system is responsible for conscious perception and voluntary motor responses.
• 🔮 Cranial nerves convey information related to the special senses such as taste, smell, vision, hearing, and balance.

Q & A

What are the two main divisions of the nervous system?

The nervous system is divided into the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and the spinal cord, while the PNS connects the CNS to peripheral structures.

What is the CNS responsible for?

The CNS is responsible for complex information processing and serves as the control center for the body, where all environmental information is processed.

What are the main components of the PNS?

The PNS consists of nerves that attach to the brain (cranial nerves) and spinal cord (spinal nerves), along with plexuses and ganglia.

What is the function of plexuses in the PNS?

Plexuses are networks of interconnected nerves that allow the redistribution of different nerve fibers into different nerves.

What are ganglia in the context of the nervous system?

Ganglia are collections of nerve cell bodies from the peripheral nervous system, such as dorsal root ganglia and autonomic ganglia.

How is the brain divided based on embryological development?

The brain is divided into the forebrain (proenkephale), midbrain (mesenkephale), and hindbrain (rhombencephalon) based on embryological development.

What are the main parts of the forebrain?

The forebrain consists of the telencephalon (cerebral cortex and subcortical structures) and the diencephalon (thalamus and hypothalamus).

How is the PNS further divided?

The PNS is divided into the somatic nervous system (responsible for conscious perception and voluntary motor responses) and the autonomic nervous system (responsible for involuntary control of the body).

What is the autonomic nervous system responsible for?

The autonomic nervous system is responsible for the involuntary control of the body, maintaining internal environment, and homeostasis.

What are the subdivisions of the autonomic nervous system?

The autonomic nervous system is subdivided into the parasympathetic, sympathetic, and enteric nervous systems.

What is the difference between the parasympathetic and sympathetic nervous systems?

The parasympathetic nervous system is involved in resting and digesting, while the sympathetic nervous system is involved in the fight or flight response.

How are peripheral nerve fibers functionally divided?

Peripheral nerve fibers are functionally divided into sensory (afferent) and motor (efferent) divisions. Sensory fibers bring stimuli from the periphery to the CNS, while motor fibers result in skeletal muscle contraction.

Outlines

00:00

🧠 Nervous System Overview

Peter from Anatomy Zone introduces the tutorial on neuroanatomy basics, focusing on the divisions and organization of the nervous system. The nervous system is divided into the central nervous system (CNS), comprising the brain and spinal cord, and the peripheral nervous system (PNS), which connects the CNS to peripheral structures. The CNS is responsible for complex information processing and serves as the body's control center. The PNS, on the other hand, receives sensory information and sends out responses to peripheral inputs. The tutorial also explains the concept of plexuses and ganglia, which are networks of interconnected nerves and collections of nerve cell bodies, respectively. Additionally, the CNS is further divided into the forebrain, midbrain, and hindbrain, each with its own components and functions.

05:00

🔍 Divisions of the Peripheral Nervous System

This section delves into the subdivisions of the peripheral nervous system, highlighting the somatic and autonomic parts. The somatic nervous system is responsible for conscious perception and voluntary motor responses, controlling the contraction of skeletal muscles. In contrast, the autonomic nervous system manages involuntary body functions to maintain homeostasis. It is further divided into the parasympathetic (rest and digest), sympathetic (fight or flight), and the enteric nervous system, which controls the gastrointestinal system. The tutorial also discusses the functional divisions of peripheral nerve fibers into sensory (afferent) and motor (efferent) components, as well as the terms somatic and visceral to describe nerves related to skin, muscles, and internal organs.

10:01

👤 Special Senses and Cranial Nerves

The final paragraph discusses the inclusion of special senses like taste, smell, vision, hearing, and balance in the context of cranial nerves. It introduces the concept of general and special nerve fibers, with the latter conveying information related to these special senses. The tutorial uses a diagram to illustrate the concepts of visceral afferent and efferent nerve fibers, as well as somatic afferent and efferent fibers, which are related to touch receptors and skeletal muscle innervation, respectively. The summary wraps up with a brief encouragement for viewers to engage with the content and explore more videos on the channel.

Keywords

💡Nervous System

The nervous system is a complex network of nerves and neurons that transmit signals between different parts of the body. It is the main theme of the video and is divided into the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord, while the PNS connects the CNS to the rest of the body.

💡Central Nervous System (CNS)

The CNS is made up of the brain and spinal cord and is responsible for complex information processing. It acts as the body's control center, processing all environmental information. In the script, the CNS is referred to as the control center where all sensory data is processed.

💡Peripheral Nervous System (PNS)

The PNS connects the CNS to the rest of the body and is responsible for transmitting sensory information to the CNS and motor commands from the CNS to the muscles. It includes cranial nerves and spinal nerves, which are discussed in the script as extensions from the CNS.

💡Cranial Nerves

Cranial nerves are part of the PNS and attach directly to the brain. They are responsible for transmitting sensory information and motor commands to and from the head and neck. The script mentions that these nerves are mostly part of the PNS.

💡Spinal Nerves

Spinal nerves are part of the PNS and emerge from the spinal cord. They are involved in transmitting sensory and motor information to and from the body below the neck. The script describes them as part of the PNS coming off the spinal cord.

💡Plexus

A plexus is a network of interconnected nerves that allows for the redistribution of nerve fibers into different nerves. The script mentions the brachial plexus and lumbo-sacral plexus as examples of these networks.

💡Ganglia

Ganglia are collections of nerve cell bodies located outside the CNS, typically in the PNS. They are involved in processing and integrating information before it is transmitted to the CNS. The script refers to the dorsal root ganglia and autonomic ganglia as examples.

💡Forbrain

The forbrain is one of the major divisions of the brain and includes structures such as the thalamus and hypothalamus. It is part of the embryological development of the brain and is discussed in the script as the proen keflon, which includes the telen keflon and dian keflon.

💡Hindbrain

The hindbrain is another major division of the brain and includes the medulla, pons, and cerebellum. It plays a crucial role in regulating basic life functions. The script refers to it as the romen keon and further breaks it down into the myen keflon and meten keflon.

💡Midbrain

The midbrain is a smaller division of the brain that is involved in processing visual and auditory information. It is mentioned in the script as the Meen keflon and consists of the tectum and tegmentum.

💡Autonomic Nervous System

The autonomic nervous system is responsible for involuntary control of the body's internal environment, including functions like heart rate and digestion. It is divided into the sympathetic and parasympathetic systems. The script discusses how it helps maintain homeostasis and includes the enteric nervous system as a less commonly discussed division.

💡Somatic Nervous System

The somatic nervous system is part of the PNS and is responsible for conscious perception and voluntary motor responses. It controls the contraction of skeletal muscles. The script explains that it is responsible for information processed consciously that results in muscle contraction.

💡Afferent and Efferent

Afferent nerves carry sensory information from the periphery to the CNS, while efferent nerves transmit motor commands from the CNS to the periphery. The script uses these terms to describe the sensory and motor divisions of the peripheral nervous system, with afferent arriving and efferent exiting.

Highlights

The nervous system is divided into the central nervous system (CNS) and the peripheral nervous system (PNS).

The CNS includes the brain and spinal cord, serving as the control center for processing environmental information.

The PNS connects the CNS to peripheral structures, receiving sensory information and sending responses.

Cranial nerves, mostly part of the PNS, attach to the brain, while spinal nerves attach to the spinal cord.

Plexus is a network of interconnected nerves that allows redistribution of nerve fibers.

Ganglia are collections of nerve cell bodies from the PNS, such as dorsal root ganglia and autonomic ganglia.

The brain can be divided into the forebrain, midbrain, and hindbrain based on embryological development.

The hindbrain further breaks down into the medulla, pons, and cerebellum.

The midbrain consists of the tectum and tegmentum.

The forebrain includes the telencephalon and diencephalon, with the diencephalon containing the thalamus and hypothalamus.

The telencephalon is the cerebrum, encompassing the cerebral cortex and subcortical structures.

The PNS is split into the somatic and autonomic parts, with the autonomic part further divided into parasympathetic, sympathetic, and enteric nervous systems.

The autonomic nervous system is responsible for involuntary control of the body and maintaining homeostasis.

The parasympathetic nervous system is involved in resting and digesting, while the sympathetic nervous system is involved in fight or flight responses.

The enteric nervous system controls smooth muscle and glandular tissue in the digestive system.

The somatic nervous system is responsible for conscious perception and voluntary motor responses, leading to skeletal muscle contraction.

Peripheral nerve fibers are functionally divided into sensory (afferent) and motor (efferent) divisions.

Sensory and motor components in the autonomic nervous system are also described as afferent and efferent.

Somatic nerves relate to skin and muscles, while visceral nerves relate to internal organs.

Cranial nerves include fibers for special senses such as taste, smell, vision, hearing, and balance.

Nerve fibers are categorized as general and special, with special senses being addressed in cranial nerve tutorials.

Transcripts

hi this is Peter from Anatomy Zone and

in this neuroanatomy Basics tutorial

we're going to take a look at the

divisions and the organization of the

nervous

system so the nervous system is divided

into the central nervous system and the

peripheral nervous system the central

nervous system consists of the brain and

the spinal cord and the peripheral

nervous system consists of those

structures which connect the central

nervous system to peripheral

structures so in this tutorial I'll

refer to the central nervous system as

the CNS and the peripheral nervous

system as the pns the CNS consists of

the brain and the spinal cord which you

can see in this diagram here so the CNS

is responsible for complex information

processing it is essentially our control

center where all the environmental

information is processed the peripheral

nervous system connects the central

nervous system to peripheral structures

it receives sensory information and also

sends out information to respond to this

peripheral

input so in this diagram you can see the

peripheral nervous system as extensions

from the central nervous system so the

pns consists of nerves which attach to

the brain and to the spinal cord so the

nerves which connect to the brain are

known as cranial nerves and I'm just

drawing these on here because it's not

represented in the diagram so the

cranial nerves are mostly part of the

peripheral nervous

system and then you can also see the

these nerves coming off the spinal cord

these are called spinal nerves and these

are also a part of the peripheral

nervous system so the cranial nerves the

spinal nerves and all their branches are

part of the peripheral nervous system

and just to point out while we're

looking at this diagram you've also got

things called plexuses so you can see up

here there's a network of interconnected

nerves this network allows the

redistribution of different nerve fibers

into different nerves and this

networking structure of peripheral

nerves is known as a plexus so the one

over here is the brachial plexus and

down here you can see another network of

nerves and this is the lumbo sacral

plexus and if you look to the side of

the spinal cord you can see these round

shaped structures these are the ganglia

so these ganglia are collections of

nerve cell bodies of the nerves from the

peripheral nervous system so examples of

these are the dorsal root ganglia and

autonomic ganglia

so before we move on let's just take a

look at the various divisions of the

central nervous system so as you know it

consists of the spinal cord and the

brain the brain can be broken down into

various different components based on

how it develops in embryological life so

what you've got is the forbrain the

midbrain and the hindbrain and

unfortunately they do have some

confusing names so the hind brain is

called the romen Keon the midbrain is

called the Meen Keyon and the for brain

is called the proen Keyon so it all

comes from Greek words now the hind

brain can be broken down further into

the myen Keyon and the meten keflon so

the myen keflon develops into the

medulla which you can see that I've

outlined in red the Met enlon forms the

pwns and the cerebellum and you can see

that I've outlined those structures in

blue

so the midbrain is referred to as the

Meen

keflon and the midbrain consists of the

tectum and the tegmentum and you can see

it highlighted here in this light blue

color now we're coming to the forbrain

which is known as the proen keflon and

this has two parts to it really it's got

the telen Keyon and the Dian Keyon what

we're looking at here is the Dian keflon

so in in the light green color you've

got the thalamus and in the orange color

you've got the high

hypothalamus so in this diagram what

we've done is we've taken A sagittal

section through the middle of the brain

so the telen cyon is essentially the

cerebrum which encompasses the cerebral

cortex and the subcortical structures

like the basil ganglia the hippocampus

and the amydala

so I've just outlined that in Red so

that's a brief run through the basic

anatomical organization of the central

nervous

system so having taken going a look at

the central nervous system let's return

to the peripheral nervous system and

look at how this is split

up essentially you've got two parts to

it you've got the sematic part and the

autonomic part so the autonomic part can

then be further subdivided into the

parasympathetic the sympathetic and the

enteric nervous system and within these

these components of the peripheral

nervous system you've also got sensory

and motor

divisions so the sematic IC nervous

system is responsible for conscious

perception and voluntary motor responses

so it's responsible for contraction of

skeletal

muscle the autonomic nervous system on

the other hand is responsible for the

involuntary control of the body so it's

involved in maintaining our internal

environment and maintaining homeostasis

it regulates that internal environment

and keeps everything under

control so to just talk about the

autonomic nervous system in a little bit

bit more detail autonomic comes from the

Greek meaning self-governing so Auto

means self and nomos means law what the

autonomic nervous system does is it

detects and monitors changes in the

activity of the viscera and it can help

to control

them it supplies and innovates things

like the cardiac and smooth muscle as

well as glands and their secretions so

as I mentioned before you've got some

subdivisions of the autonomic nervous

system and these subdivisions tend to do

opposite things to each other and in

this respect they're

antagonistic so the two main components

are the parasympathetic and the

sympathetic nervous system so the

parasympathetic nervous system is

involved in resting and digesting

whereas the sympathetic nervous system

is involved in the fight and flight

response so parasympathetic rest and

digest sympathetic fight and flight and

this is a broad generalization but it

helps you to get an idea of the function

so these divisions are distinct both fun

functionally and

anatomically the final division of the

autonomic nervous system the third

division Which is less talked about is

the enteric nervous system and this is

located in plexuses within the

gastrointestinal system and it's

responsible for controlling smooth

muscle and glandular tissue in the

digestive

system now just to come back to the

sematic nervous system this branch of

the peripheral nervous system is

responsible for conscious perception and

voluntary motor responses so this

diagram just shows how a peripheral

stimulus can be picked up and

transmitted along a neuron a sensory

neuron into the central nervous system

and then the central nervous system can

coordinate a response and cause sceletal

muscle contraction in response so the

sematic nervous system is responsible

for consciously processed information

that results in sceletal muscle

contraction now this brings me on to the

next division that we can make within

the nervous system so we've talked about

the different components of the

peripheral nervous system and now we can

talk about the peripheral nerve fibers

in terms of their functional divisions

so right here we can talk about the

sensory and motor divisions so the

sensory division of the peripheral

nervous system is known as the afferent

division whereas the motor component the

part which results in sceletal muscle

contraction is known as the efferent

division in this diagram the blue axon

represents the sensory division so this

is the division which brings the

stimulus from the periphery into the

center and the efferent division is

represented by this red neuron so this

red neuron is a motor

neuron so you've got this functional

division of neurons into sensory and

motor sensory are afferent motor are

efferent and in the monic for this is

the word same so s a m sensory afer

motor eant and how you remember whether

afren or ephant leaves or goes towards

the central nervous system is using the

pneumonic afferent arrives efferent

exits now in terms of the autonomic

nervous system you've also got sensor

and motor components or afferent and

efferent components so taking a look at

this diagram just to illustrate the

point we've got a sensory nerve ending

up here which is detecting some kind of

peripheral stimulus for example example

it could be detecting stretch in the

aortic or cored sinuses so stretch in

the smooth muscle wall of a blood vessel

and it feeds back into the central

nervous system and a response is

provided to relax the smooth muscle wall

so you've got a sensory component which

picks up that stretch in the coridor

aortic sinuses in the blood vessel wall

and then you've got a motor component or

an eant component which feeds back to

the blood vessel smooth muscle so that's

an example of afer and efferent

components in the autonomic nervous

system so sensory and motor

components other words used to describe

functional divisions in peripheral

nerves are somatic and visceral so

somatic just refers to skin and muscles

and visceral refers to nerves innovating

internal organs so there's a few words

now that we've used to describe the

functional divisions of peripheral nerve

fibers sensory and motor synonymous with

AFR and eant and now we've talked about

somatic and visceral relating to skin

and muscles and internal organs

respectively when you talk about cranial

nerves another element is thrown in you

actually have nerve fibers in the head

which convey information relating to the

special senses so now you've got taste

smell Vision Hearing and Balance thrown

into the mix and because you've got

these special Senses nerve fibers are

also divided into General and special

but we'll take a look at this in the

cranial nerve nerve tutorials so just to

put these examples into context let's

use this diagram here to combine those

words we've just talked about so this is

a nerve picking up a peripheral stimulus

for example in the from the blood vessel

wall this stretch receptors in a blood

vessel wall so this is visceral because

it's relating to blood vessels and it's

also bringing information into the

spinal cord so bringing it into the

center so it's an afen neuron this would

be called a visceral afren nerve fiber

now the nerve fiber leaving from the

center to innovate the smooth muscle

wall and cause relaxation or contraction

is called a visceral

eant so we've got a visceral affrant and

a visceral

eant now coming back to this diagram

we've got an affrant nerve fiber

conveying a peripheral stimulus from the

hand so from a touch receptor so this is

a sematic arrant and then you've got

this nerve fiber which begins in the

vental Horn of the gray matter of the

spinal cord and it innovates skeletal

muscle so this is a motor neuron and

it's eant so this is a sematic eant so

we've got a sematic affrant and a

sematic eant fiber or a motor

fiber so that's an overview of the

divisions of the nervous

system if you found this video helpful

please click the like button subscribe

to our Channel and make sure you check

out some more of our videos thank you

for watching