One Time
  • 3 months ago
HEALTHY HABITS:
Healthy habits change your life.

https://rb.gy/qm6cbt
The Ultimate Healthy Habits Ebook⚡️
"The Ultimate Healthy Habits Ebook" is your go-to guide for transforming your lifestyle. It covers nutrition, fitness, sleep, and mindfulness, offering simple, actionable tips to help you build lasting, healthy habits for a better life.

https://bitly.cx/MoRg
Keto Desserts - High Converting Keto Desserts Offer
Book (printed).
"Keto Desserts" is a high-converting printed book packed with delicious, low-carb dessert recipes that fit perfectly into a keto lifestyle. Satisfy your sweet tooth without compromising your diet!

https://bitly.cx/WrAJ
Home Doctor – BRAND NEW!
Book (printed)
"Home Doctor – BRAND NEW!" is a printed book offering practical medical advice for treating common health issues at home. It includes step-by-step guides, natural remedies, and essential tips for everyday emergencies and ailments.

https://bitly.cx/QqkC
12 Fitness Videos
Downloads.
"12 Fitness Videos" is a comprehensive video series designed to help you achieve your fitness goals. Featuring a range of workouts from beginner to advanced, these videos provide effective, easy-to-follow routines for every fitness level.

https://rb.gy/b01vbi
Lost Frontier Handbook
Book (printed).
The "Lost Frontier Handbook" is a printed guide that teaches essential survival skills and self-reliance techniques from a bygone era. Learn to thrive off the grid with practical advice on homesteading, foraging, and more.

https://rb.gy/jle6zd
Herbs For Health - Only Herbal Remedies Offer!
EBooks.
"Herbs For Health" is a unique guide focusing solely on herbal remedies. Discover natural, effective treatments for common ailments using herbs. This offer provides a wealth of knowledge on holistic healing and wellness.

https://rb.gy/ujlkti
Silence Tinnitus and Hearing Issues with Zeneara!
Supplements - Health.
"Silence Tinnitus and Hearing Issues with Zeneara!" offers a natural supplement designed to support ear health and reduce tinnitus symptoms. Experience relief with this carefully formulated blend of herbs and nutrients.

https://bitly.cx/mLHve
EMFDEFENSE™ Negative Ions Sticker
The EMFDEFENSE™ Negative Ions Sticker is designed to protect you from harmful electromagnetic frequencies (EMF) by emitting negative ions. Easy to apply on devices, it helps promote wellness and balance in everyday environments.

https://rb.gy/38zkvk
SurvivalMD
Book (printed)
"SurvivalMD" is a printed guide that provides essential medical knowledge for emergency situations when professional help isn't available. Learn practical, life-saving medical skills to manage health crises during disasters and off-grid living.
https://bitly.cx/mw6D
Old School New Body
EBooks
"Old School New Body" is an ebook program designed to help you lose weight, build muscle, and slow aging using proven, old-school fitness techniques. It features easy-to-follow workouts and nutrition tips for lasting re
Transcript
00:00Hello, a little bit frazzled today because I'm trying to squeeze this in amongst lots
00:07of other teaching stuff I've got to do, but what I thought we'd do is we'd do an introduction
00:13to the nervous system as a whole, the anatomy of the nervous system. So we'll talk about
00:18a neuron and then from there, well I guess we'll start at the top and we'll work our
00:21way down and out and the main aim will be to cover the major terms, the major structures.
00:30So when you come across them elsewhere, you know what people mean when they say spinal
00:33nerve, medulla oblongata and things like that, okay? And I'm going to be really careful to
00:39not go into too much detail. So this isn't going to be detailed, this is going to be
00:43introductory, there's other detailed stuff to go and look at, all right? Right.
00:50A pipe cleaner, that's an idea. We use pipe cleaners for making things and poking skulls
01:05and that sort of thing, but if we're to consider a neuron, a neuron then is the basic cell
01:11of the nervous system and a neuron has a, you know, there are various types of essentially,
01:17if you think about a neuron as having a cell body at one end, all right, so the nucleus
01:25and it's got a little bit of a fat bit there, the cell body is at one end and then it sends
01:29off a long axon to somewhere else in the body and that may be very, very long, it might
01:35be more than a metre in you, it might be many metres long in a blue whale, so these are
01:38incredibly long cells, but a neuron sends an axon down to meet another neuron or to
01:46become a receptor for something or motor to something like trigger a muscle contraction
01:51or something like that and that is what the nervous system is largely made up of and that
01:56is the cell and the shape you should be thinking about when we're thinking about the wiring
02:01of the central nervous system, the neuron. There are other cells in the nervous system,
02:06there are lots of supportive cells and connected tissue cells and fat producing cells and all
02:10sorts of other cells, but functionally, that's our guy, all right? So when we talk about
02:16grey matter and white matter, the grey matter, those are collections of nerve cell bodies,
02:23so the cell body, the neuron cell body there and they, so for example in the brain, the
02:28grey matter is around the outside, it's more superficial and the white matter, when we're
02:35talking about white matter, we're talking about axons covered in myelin, fat, which
02:39is why they look white, so nerves again, when we look at, when we think about nerves, they
02:45are bundles of neuron axons generally covered in myelin, so grey matter and white matter.
02:56The brain, or the brian as many students seem to spell it in some anatomy exams, the brain
03:02has a number of lobes and we can see these sulci and gyri, the gyri being the fold and
03:09the sulci being the depression, which give a lot more surface area to the brain, so a
03:14lot more room for grey matter, so a lot more room for more neurons, more neurons, more
03:20connections, more complexity. And it has a number of lobes, we have the frontal lobe,
03:25parietal lobe, temporal lobe and occipital lobe and these are all parts of the cerebrum
03:31and there are two cerebral hemispheres, left and right, split down the middle but joined
03:36by big tracts of white matter, so they do communicate, so those are the cerebral
03:41hemispheres, this is the cerebrum and then coming out of the cerebrum, descending down
03:50here we have, well in the centre there we have the midbrain, which we can't really see,
03:54it's surrounded by the rest of the cerebral hemispheres up here and then we have the pons,
04:01it's curved like a bridge, pons, pont, so we have the pons and the medulla or the medulla
04:07oblongata and then the medulla oblongata continues as the spinal cord descending down through
04:13the back. So that's the brainstem, the midbrain, pons and medulla comprise what we call the
04:21brainstem and we can see a number of nerves coming out of the brainstem and indeed coming
04:27out of the cerebrum and these nerves we call cranial nerves because they come out of these
04:35parts. If we spin around posteriorly we see these chunks of tissue here, these are the,
04:43well this is the cerebellum and the cerebellum, I'm keeping it simple, let's not talk about
04:53functions, we're just talking about names. So the cerebellum is attached to the brainstem,
05:03boom, okay, so then spinal cord, so then the spinal cord is a continuation from the medulla
05:14oblongata through the vertebrae all the way down the back, I say all the way down the back,
05:19in adults the spinal cord is not the same length as the vertebral column, so the spinal cord
05:25actually ends here and what we can see here are spinal nerves running down which we'll talk about
05:29in a moment. But that's the central nervous system, so the cerebrum, the brainstem, the cerebellum
05:42and the spinal cord are the central nervous system which is commonly abbreviated to CNS.
05:50The other division of the nervous system is the peripheral nervous system,
05:54the PNS. Now the peripheral nervous system is everything that comes out of the central nervous
06:00system, so here we see spinal nerves coming off regularly and other nerves, those are all parts
06:06of the peripheral nervous system, and those cranial nerves that we see here are also parts
06:12of the peripheral nervous system, all right. So what's a spinal nerve then? Well, a spinal nerve
06:21is a nerve that leaves the spinal cord and passes off to somewhere else in the body, and we've
06:28talked about all of these things in more detail elsewhere, so I'll leave that to those videos,
06:33but remember our basic building block of the neuron. A spinal nerve then is a collection of
06:39lots and lots of neurons, some of them are sensory and some of them are motor, and they're all
06:45bundled together and the reason they're running together as a spinal nerve really is because
06:51they're all going to a similar location. We're a segmented animal and we can see that these spinal
06:57nerves are showing us those segments, those segments are most obvious in the ribcage,
07:02but they continue elsewhere throughout the body, and sometimes those spinal nerves come together,
07:07so this is the brachial plexus forming up here, these are the nerves that are going to supply
07:12the upper limb. We can see these spinal nerve roots coming together very soon after they leave
07:19to form new nerves, because by coming together they're forming, you know, new structures,
07:24anatomists like to name everything, so we'll give those new names, and then they change and link and
07:28change and blend and join and eventually form the major nerves of the upper limb. And the plexus
07:34then, a plexus is, it's like an organization of wires, it's like wiring, the nerves are all
07:41crossing over and joining and forming new nerves, but there aren't any connections in there, it's
07:46just cabling, it's just cable management, that's a plexus. Whereas a ganglion, which is what we're
07:55seeing here, a ganglion is a collection of neuron cell bodies outside the central nervous system.
08:05We would call, I said that gray matter is collections of nerve cell bodies, but a ganglion,
08:15this mass that we can see here, if we see a ganglion inside the central nervous system,
08:19it tends to be called a nucleus, but a nucleus inside the central nervous system is, again,
08:24just a collection of nerve cell bodies. See, terminology is one of the first things that can
08:29trip you up when trying to learn neuroanatomy, and neuroanatomy is hard enough as it is.
08:34So, the spinal cord descends and gives off a number of spinal nerves, and those run off to
08:39their target organs and tissues and what have you, bam, job done. They might be
08:45innervating muscles and causing them to contract, they might be carrying all sorts of sensory
08:48information back, and there are maybe one or two connections between that nerve
08:53and the central nervous system before they get to the higher centers, but as I said, that's all
08:57covered elsewhere. So, we were talking about the spinal cord, there is another video about the
09:01spinal cord, but the spinal cord only reaches this far, and then all these spinal nerves that you see
09:08leaving the vertebral column at regular intervals, when we get down here into the, so we're into the
09:15lumbar region, the sacral region, those spinal nerves just carry on running down inside the
09:21vertebrae and then leave a little bit later. So, if you were just to look at the spinal nerves
09:26leaving the vertebrae, it remains this nice neat segmented pattern that you would expect to see,
09:32it's only when you look inside the vertebrae that you see that in fact the spinal cord has ended
09:36here and the spinal nerves are forming like a horse's tail, the cord required down here.
09:42That's almost it, isn't it? Because not only do we divide the nervous system into central nervous
09:48system and peripheral nervous system, but we also divide it into autonomic and somatic.
09:55Now, somatic, soma, soma meaning the body, so the somatic nervous system means of the body,
10:01and essentially it's, the somatic nervous system is involved with things you can,
10:09things you can consciously control or things that you are consciously aware of.
10:14The best examples are of, are this, so somatic motor control is I'm deciding to make these
10:21movements and I'm making them, so that's the somatic nervous system that's controlling my
10:27skeletal muscles. And when I poke my skin, when I get stung by a bee, when a wasp, when a fly
10:38flies into my eye, those are things I'm very consciously aware of, so that would be the sensory
10:45side of the somatic nervous system, so of the body, do you see what I mean? Whereas the autonomic
10:51nervous system is involved with things that we're not consciously aware of. If we think of a motor
10:58example, the autonomic nervous system would be involved in controlling the muscles in the GI
11:05tract that pass your food along the tube, you really don't want to be aware of that, you don't
11:10want to have to think about where something is and then move it along, no, no, no, no, that's what the
11:14autonomic nervous system does, it's automatically looking after your GI tract for you, you're not
11:21even aware of it, you can't be aware of it unless you have some pain or something. So then the
11:27sensory side of that, of the autonomic nervous system, again would be carrying sensory things
11:32back from the gut, but another good example would be blood pressure and blood gas, blood gas levels.
11:42So in some of the major blood vessels in the body and deep inside the brain, there are baroreceptors
11:50and chemoreceptors, and those baroreceptors are looking at the stretch in artery muscle walls, so
11:57they can look at the blood pressure in that blood vessel, and chemoreceptors are looking at
12:03the chemical composition of the blood and sending that information back to the brain, so the brain
12:08is aware of how it needs to modulate the blood vessels in the body and the heart to manage blood
12:15pressure and to make you breathe in faster or slower to make sure the chemical composition
12:23of the blood in terms of oxygen and carbon dioxide and what have you is appropriate. Do you
12:27see what I mean? So the autonomic nervous system has a sensory function in monitoring your body
12:33and making sure it is as it should be, and then autonomically changing things to make sure we
12:40have this level of homeostasis to make sure things are as they should be. So that's the
12:44autonomic nervous system, but what about physically? Well somatic, okay, so I was talking about the
12:50brachial plexus. Most of the nerves of the brachial plexus are innervating skeletal muscles
12:55of the upper limb and carrying sensory innervation back from the skin of the upper limb. So these
13:00nerves are very big because they have a large number of neurons. It's a physical thing. If you
13:07have greater sensitivity in your fingertips, you need more sensory neurons. More sensory neurons
13:13means that nerve gets bigger. So the brachial plexus might be a really good example of a section
13:19of the somatic nervous system. Now most of these spinal nerves will in fact be mixed. They'll have
13:27autonomic fibres and somatic fibres in there because in your skin you are autonomically
13:35controlling blood flow to your skin. When you're hot, more blood flows to your skin. You lose heat
13:40and when you're cold, less blood flows to your skin. That's all under autonomic control.
13:45That's the smooth muscle in the arterioles being controlled there. Also the hair sticks up and so
13:51on, right? So throughout your body, particularly the skin and elsewhere, but most of these nerves,
13:58most of the nerves in the body are mixed and are carrying autonomic nerves and somatic nerves.
14:05So it's not an easy physical distinction to make. It's more of a thoughtful distinction.
14:10But we can see some autonomic structures. So this here, these ganglia, this is the
14:19sympathetic trunk or the sympathetic chain or sympathetic ganglia. And what these are, are,
14:26okay, so the sympathetic and parasympathetic divisions of the nervous system are both
14:34parts of the autonomic nervous system. So the autonomic nervous system gets divided into
14:38sympathetic and parasympathetic. And all sympathetic and parasympathetic neurons are
14:44motor. They're all driving something. And then you'll have visceral sensory fibers coming back,
14:51visceral afferents, which would be part of the autonomic system, really. They're the sensory part.
14:56So the sympathetic nervous system, and there's a whole video on this, I'm sure, it originates in a
15:02section of the spinal cord. It sends a neuron out to a sympathetic ganglion. It meets another neuron
15:09there because, of course, a ganglion is a cell body sending out another axon. So we have a
15:15collection of sympathetic nerve cell bodies here. And then the sympathetic neuron from the ganglion
15:19runs out with another nerve, usually, to get to wherever it's got to go. So the sympathetic
15:27nervous system comes out of the spinal cord. The parasympathetic nervous system
15:34is described as craniosacral. Craniosacral. So this is the sacrum down here. And that's because
15:44parasympathetic neurons that are driving parasympathetic things come out of the brain.
15:50The vagus nerve is probably the biggest and most famous one. And the vagus nerve carries
15:54parasympathetic fibers from the brain down through the body to your GI tract, your abdomen,
16:00and what have you. But it doesn't reach all the way down to your pelvis. So there are also some
16:05sacral parasympathetic neurons in the spinal cord that come out of the sacral vertebrae and carry
16:12parasympathetic innervation to the pelvis and what have you. So sympathetic and parasympathetic
16:17innervation is largely to organs. And you may well know this already, but they get described
16:24in two different ways. So the sympathetic nervous system is described as your fight or flight
16:30response because it's involved with adrenaline. And it can also result in a release of adrenaline
16:37into the blood, which triggers all of your sympathetic stuff. So the fight or flight
16:41response gets you ready to flee. It fires up all your muscles, releases a whole bunch of energy,
16:47gets you like superpowered, ready to run or to fight. So it's a survival thing.
16:53Whereas the parasympathetic division of the nervous system is kind of the opposite. It's
16:58described as rest and digest. So the parasympathetic nervous system is largely driving, for example,
17:05your gastrointestinal tract. So you have a meal and it drives all of those functions.
17:10And in many parts of the body, they kind of work in opposition.
17:14You know, like they'll both, both sympathetic and parasympathetic nerve fibers will run to the heart
17:20and will affect the rate at which the heart beats and the force of contraction of the heart.
17:25And that's quite a good example of them working in opposition. One will speed your heart up,
17:30one will slow it down. You can probably work out which is which. But in other areas of the body,
17:34they don't always work in opposition. It's a little bit more complicated than that.
17:40How's that? I think I've achieved what I set out to do, which was to give an overview
17:46of the anatomy of the nervous system. So what we wanted to do was be able to identify
17:51the parts of the brain and the parts of the central nervous system and know what those
17:55terms meant. So we can recognize the cerebral hemispheres, the cerebellum, the midbrain,
18:00the pons and the medulla, and then the spinal cord. We've talked about cranial nerves and spinal
18:06nerves, and we've split the nervous system into somatic and autonomic. And we've talked about
18:13some of those structures. And then we've talked about how we divide the autonomic nervous system
18:18into sympathetic and parasympathetic. That's a really good starting point.
18:25I mean, I don't find neuroanatomy easy. And what I try to do when we're teaching students here,
18:30because some are very good, and some are not very good, and some, you know, as they find it
18:34difficult, what I'm trying to do is just try and get everybody up to the same level. And then when
18:38we're all on that same level, we can add detail and add detail and add detail slowly. But if you
18:43don't get up to that initial level, the rest of it just gets really patchy. All right.
18:51Right, I better go do get ready for my next thing. See you guys next week.