So this video is going to be part two of the nervous system review. So in the previous video we were discussing the parts of the central nervous system and we discussed the areas of the brain, the brain, the brain, the lobes of the brain and what some of those functions were. So the main thing to remember about the brain is it cannot expand.
So therefore any bleeding or any increased pressure, anything inside that cavity can push into something else to push that aside and displace it. So then that's where a lot of the problems do come from. And then on the screen you'll see the spinal cord. So the spinal cord is the other part to the central nervous system. And so you'll still follow along of course with the same outline.
So the spinal cord, it is a 17 to 18 inch long cord. It extends from the first cervical to the second lumbar vertebrae, as you can see there on the screen. The main functions of the spinal cord are to transmit sensory information to the brain and motor information from the brain. So transmit sensory info to the brain and motor information from the brain.
And it produces reflexes by 31 spinal nerves. And we'll talk about those. nerves here in just a second.
Of course the spinal cord is very sensitive so therefore it does tolerate injury very poorly so oftentimes any injury to the spinal cord does produce debilitating results and can be severe results that cause permanent damage. So you can see there on the screen You have the cervical vertebrae, and again we're going to talk about the spinal nerves here again in just a second, the thoracic vertebrae, your lumbar vertebrae, and then the sacral vertebrae. So the second portion then of the second division of the nervous system is going to be the peripheral nervous system. So you can see there on the screen the peripheral nervous system it says carries information to and from the central nervous system. Remember we talked about the different types of neurons that carry that information your afferent and your motor sensor sensory neurons.
So within that peripheral nervous system you have your sensory division and then you have your motor division you can see there the sensory division. You have your somatic sensory and you have your visceral sensory and then the motor division. You have your somatic and you have your autonomic system that is broken down into the sympathetic and the parasympathetic.
So we'll talk about that here in detail in just a few minutes. So we do want to talk about the spinal nerves real quickly and just talk about kind of what each of those are. So the spinal nerves and their function here are on your screen.
You can see that there are 31 pair of spinal nerves as mentioned just previously and those are named according to their corresponding vertebrae. So for example C2 or C3. So there are eight cervical spinal nerves, there are 12 thoracic spinal nerves, there are five lumbar and five sacral. And there's actually a coccygeal nerve. There's actually one of those that sometimes isn't really counted in that number.
So but there are 31 total, but you just don't hear a lot about the coccygeal nerve. But there are 31 total. So which does include the coccygeal nerve.
Sorry, I didn't mean it wasn't counted in the 31. So there's eight, 12, five, five, and then the one coccygeal, but you just don't hear as much about that one. So you can see C1 to C4 is responsible for breathing. C2 is your head and neck movement.
C4 to C6 is heart rate. Six is shoulder movement. Five is wrist and elbow movement. So you can just see there on your screen again.
I'm not asking you guys to memorize these, but it's just important to kind of understand. You just kind of know that obviously that each nerve and each area does have different functions for the body and obviously without the spinal cord and certain injuries at a certain level you know do cause a lot of problems so and we'll be talking more about those and of course these spinal nerves carry impulses to and from the spinal cord. All right, the next thing are the cranial nerves.
So there are 12 pair of cranial nerves and these cranial nerves carry impulses to and from the brain. There is a table in your book that has these cranial nerves and actually there's two different places I think and then there's there's a couple there's a table and then maybe a picture in your book. So you've often referred to those as well as of course you have pictures on your screen. So Right now what I'm going to talk about is just what each of those cranial nerves are and what their function is. However, when we talk about assessment, we will actually talk about how to assess each of those.
So the cranial nerve one is considered the olfactory nerve and it carries impulses from the nose to the brain. So your olfactory nerve is primarily responsible for smell or sense of smell. Cranial nerve two is the optic nerve. which carries those impulses from the eye to the brain.
So the optic nerve is responsible for vision. Cranial nerve three is oculomotor, which carries those impulses from the brain to the eye muscles. So it's a motor nerve and it's responsible for pupil constriction. So for example, for patients pupils aren't constricting, then they have some type of issue with cranial nerve three.
cranial nerve four is the trochlear nerve which carries those impulses from the brain to the external eye muscles this is also a motor nerve so it is responsible for down and medial eye movement so and you'll see when you assess these cranial nerves there's a lot of times there's certain assessments that you do and it will test multiple of these multiple nerves at the same time cranial nerve five is the trigeminal nerve and it is responsible for carrying those impulses from the skin and the mucous membranes of the head and then from the teeth to the brain. Also from the brain to the chewing muscles. Let's try geminal.
Six is called abducens, which carries impulses from the brain to the external eye muscles. Again, that is a motor nerve. And you can tell that that is very similar to the trochlear.
So again, you will be assessing those at the same time. And that's responsible for lateral and outward eye movements, whereas the trochlear was responsible for the down and medial eye movements. Cranial nerve 7 is the facial nerve, and it is responsible for those impulses from the taste buds of the tongue to the brain, also from the brain to the facial muscles.
And cranial nerve 7 is actually a motor and a sensory nerve. So we'll also talk about are those nerve sensory, have sensory function or they have motor function. And if you can memorize if it's sensory or motor, then that also helps you kind of memorize what the function of that nerve is. And again, we'll talk about that with assessment.
But some of them do have both. So the facial muscle or facial nerve, for example, does have motor and sensory functions. Cranial nerve 8 is what we call acoustic or sometimes that is referred to as vestibulocochlear and is responsible for those impulses from the ear to the brain. So acoustic, you think about hearing and balance.
So acoustic, vestibulocochlear, you hear both of those used so that's going to be hearing and balance. Cranial nerve 9 is the glossopharyngeal nerve and it is responsible for those impulses from the throat and the taste buds of the tongue to the brain. Also, it is responsible for impulses from the brain to the throat muscles and the salivary glands.
So you can imagine that since it has to deal with throat muscles and also some taste buds, then the glossopharyngeal is a sensory and motor nerve as well. Cranial nerve 10 is the vagus nerve. So it carries impulses from the throat, the larynx and the organs in the thoracic and abdominal cavities to the brain. also from the brain to the muscles of the throat and to the organs in the thoracic and abdominal cavities so again it is also sensory and motor cranial nerve 11 is the spinal accessory nerve and it carries impulses from the brain to certain shoulder and neck muscles so it's going to be considered a motor a motor nerve and cranial nerve 12 is the hypoglossal nerve and it carries impulses from the brain to the muscles of the tongue so therefore that is also a motor nerve. And there will be some other handouts, posted pictures, things like that that you guys can have access to print off so that you can, you know, be able to refer to those easily as well.
So those are the 12 cranial nerves. Again, we'll talk about assessment of those and a little bit more detail about those when we get to the assessment. Now I do want to go ahead and kind of go ahead and throw this out there but there are there are lots of acronyms mnemonics for memorizing the cranial nerves and you know in nursing we don't tell you to memorize a lot of things but this is kind of one of those things where you just have to memorize it.
So this is one way of memorizing um um doesn't matter to me how you choose there again there's different sayings so whatever works for you but you can say this in your head and it kind of helps you too. remember what number the cranial nerve is. So then if you memorize the number, then hopefully you can memorize kind of what goes with it and how to assess it.
So on old Olympus's towering top a fin in German Witzelhop. So again you can see what they refer to there. And really you know like your first three olfactory optic oculomotor.
You just kind of have to keep that in your head because they both begin with the same letter obviously. Just kind of get that in your head to think what each of those are. You know, just make yourself say olfactory optic oculomotor and just know that they go in that order. All right. So the next thing we're going to talk about is the autonomic nervous system.
So the autonomic nervous system, this is basically two divisions that work opposite of each other. One actually slows in action. while the other speeds up the action.
And so again, you kind of just have to memorize these and hopefully from anatomy and physiology, you remember these and, you know, we'll bring back some of that memory. However, though, the primary function of the autonomic nervous system is to maintain or keep a stable internal environment. So just to maintain that homeostasis is that main function of the system in general.
They just work opposite of each other. So your sympathetic system, that's going to be what we refer to as that fight or flight response. So your sympathetic system is what's activated during times of stress. And it causes such things as increased heart rate, increased blood pressure, dilation of bronchioles, dilated pupils. Also causes decreased gastric secretions, increased adrenal gland secretion.
So that comes from like cortisol, which has to do with the metabolism of the fats, the carbs, some of your electrolytes, sodium, potassium, proteins. And then aldosterone works to increase the sodium absorption, for example, and then that increases blood pressure, it lowers potassium. And then also epinephrine or epinephrine has to deal with some of those neurotransmitters as well.
So that's kind of some of those things that the sympathetic nervous system does. It's that flatter fight. It's just kind of when we're stressed, these are the things that happen.
And really, you know, all in all, again, the function of, again, the primary function is to kind of keep that homeostasis. So that sympathetic response when we're stressed or when something happens suddenly, it really just helps to enable us to be physically prepared to handle some potential danger. So... something happens it kind of that fight or flight kicks in and we become more aware really of what's going on so that we're kind of we're ready to kind of handle whatever may be happening and then the parasympathetic system is kind of what happens after the crisis so it's kind of that rest and digest moment so it's going to kick in after a crisis in order to restore and conserve our body functions because you know we can only and you all learn from mental health you know we can only be in that fight or flight stage or you know we can only if a person can only handle so much stress or so much anxiety at one time something has to give and that's where that parasympathetic system kicks in so it's trying to restore and trying to conserve those body functions so it's going to decrease the heart rate it's going to decrease the blood pressure it's going to cause those pupils to constrict cause those bronchioles to constrict it's going to decrease the adrenal glands secretions and then our GI motility will increase so and there's some other things listed there on the screen that you can see but for the most part that's going to be the main functions and the main the main things that are controlled by that by that sympathetic and the parasympathetic okay so that pretty much concludes the the different parts of the system and so the last thing that we are going to talk about or just some changes that can occur within the nervous system that come with age. And then we'll talk about, we'll click at the end, just some prevention.
So, of course, as the person ages, there are going to be a lot of things that change within the nervous system, particularly. So some things that happen within the brain, you're going to see a loss of brain weight and a loss of those neurons. So neurons do not reproduce after the neonatal period. So that first 28 days of life, the neurons do not reproduce after that point. And then we lose.
approximately a percent of neurons per year after the age of 50. So then you can see why we decrease that weight and why we lose those neurons. Also there's a decrease in blood flow to the brain. So we know that blood you know a lot of decreases in everything in general when changes with the body with age but there is that decrease in blood flow.
There's also that decrease in use of oxygen. Of course there's short-term memory. Effects that do occur as the person ages, they will kind of lose that short-term memory.
And that short-term memory we know is affected more so than long-term memory. Because even myself now, I can't sometimes remember what I did yesterday, but I can probably recall everything that happened to me on the first day of kindergarten. You know, so that long-term memory is still in effect, but then we have those problems with the short-term memory as we age.
Also, there's the speed of learning decreases with age, but there still is the ability to learn. So that's why we still want to make sure that we're teaching our patients things about medications or disease processes as they age, although that they just don't learn as fast, but they do still have the ability to learn. And of course, there's an altered sleep-wake ratio. So as we age, we typically require less amounts of sleep than we did when we were younger.
Okay, so other changes with age. There's also changes in that hypothalamus. So there's the decreased ability to maintain body temperature.
So, you know, oftentimes we see that there's a decreased temperature as the person ages, but it's just that overall ability to maintain the body temperature decreases. And then changes in the neuromuscular area. Oftentimes tremors can become evident, which do increase with fatigue.
So as the person ages, also arthritic changes are common and those can cause nerve irritation. They can also cause joint injuries. And of course, the person may have even chronic pain along with that. There's also a decreased sense of touch. So, you know, a lot of times with the elderly, their burns are more severe because they touch something they don't know it's hot.
So therefore, they come into contact with the hot surface a lot longer. So therefore, the burn is more severe. just due to that decreased sense of touch. Also, there's a decrease in fine motor coordination. So, you know, a lot of things there with ambulation, range of motion in general.
Reflexes are slower. There's also a slower reaction time to events or to happenings. There's also decreased vision, which is why we want to be sure to provide a well-lit room for our patients. Pulling the blinds to decrease the glare, you know, just because they do have the more difficult problems seeing. Also, of course, hearing decreases, but we still want to just be sure to speak in that controlled voice.
Don't be yelling, you know, kind of a low-pitched voice usually helps better. Making sure that we sit in front of them, they can see our face, they can see our lips moving. And then there's also decreased balance.
So just be sure to provide safe. you know safety measures in order to prevent falls so it's got interventions on there but pretty much already covered that so again like due to the um decrease in touch just making sure that they're aware of um safety like with cooking or even like things with um like using like heat pads at home a lot of times they want to use heat pads but they have other conditions as they age for example if they have decreased you know peripheral um circulation because they have diabetes maybe you know again that even increases even more they don't feel that burn from that heat pad we actually had a patient one time we took care of that had really bad burns from they were diabetic and they had left a heat pad on too long on their on their legs so we talked about some things with hearing and for balance so again when talking about these changes I think across the lifespan or in relation to the patient who is aging within, you know, with that nervous system, it's just important to remember that, for example, things like dementia, like those are not normal, but neither is, you know, when a person becomes senile, quote unquote, Alzheimer's, organic brain disease, you know, those things, they're not normal, okay, but we do know that things happen just with age, but, you know, there's a lot of older and elderly patients that never experience any forms of dementia necessarily. You know, it could just be a result of some other reversible conditions such as anemia, maybe drug toxicity, malnutrition, or maybe even low blood pressure.
So just understand that these things here that we just discussed are normal changes in the nervous system that are related to aging. They are not the same thing as some of those disorders that we talked about, organic brain disease or Alzheimer's or dementia. Okay, those are actually abnormal.
diseases that happen, but these things here are normal. So, but again, you know, even the normal changes that we discussed, it does make the care of the elder patient still a challenge. So we do still just need to always make sure that we keep these things in mind. And the last slide here is just going to talk about how to prevent some neurological conditions. So you know looking at you know there are many changes that do occur in the nervous system that have a no known cause and due to the ability to prevent all changes you know are impossible of course but it is important to try to prevent certain things if we can.
Also, you know, it's important just to remember that patients, you know, can still change certain factors in their lifestyles, which may reduce the chance of some of the changes within that neurological state from occurring. So that's kind of what we're going to talk about. So we do want to try to decrease the risk that increases cardiac disease. So, for example, controlling hypertension, controlling high cholesterol levels. So we know that right there, you know, we can change our diet.
For example, you know, that could help with both of those exercise. Cigarette smoking would be another thing that we would want to try to decrease because that also decreases the chances of lung cancer which might metastasize to the brain you know if they were to decrease cigarette smoking. Obesity of course, can increase cardiac disease, stress, lack of exercise. So again all of those things we want to try to that all these things that can increase cardiac disease, we want to try to decrease those in order to decrease the risk of any neurological conditions occurring related to those.
And again, you know, all of those factors pretty much I just talked about with the risk that increased cardiac disease can cause atherosclerosis, which can cause like a decreased blood supply to the brain and to the spinal cord, and therefore we know that that could increase the risk of stroke or cerebrovascular accident. So Again, that's kind of the connection there with how to prevent the neurological conditions. Risk for trauma.
So we want to try to prevent any risk for trauma, which would be more common in younger adults. So avoiding the use of alcohol and drugs, being sure to have safe use of motor vehicles, so wearing seat belts, wearing helmets while riding bikes or four wheelers, skateboards, motorcycles, those things. Safe swimming practices. Just, you know, just Being careful to not dive in shallow water.
You know, they put those signs up on swim pools for a reason because, you know, that can cause spinal cord trauma. If a person was to dive in shallow water and hit their head or can cause their spinal cord problem. Just being careful with firearms and storing those correctly, handling those correctly with extreme caution. You hear every day in the news of someone innocent who was shot by a gun just due to... poor handling of it you know just was cleaning it or you know just wasn't handling it correctly always wearing hard hats in construction areas and then wearing protective proper protective equipment when playing sports also we want to treat ear and sinus infections promptly so we want to do this because some of those causative organisms can actually spread to the brain and could cause neurological conditions so for example meningitis or they could also cause brain abscesses so do want to make sure that those ear and sinus infections are treated promptly and then safe sex practices basically you know this can prevent neurological conditions because STDs for example such as syphilis and HIV can actually lead to neurological changes such as encephalitis so practicing those safe sex practices to prevent neurological conditions so whether it be you know abstinence you see using of condoms um you know being in a monogamous relationship you know where there's just one partner and then um of course drug abuse treatment especially if it is an iv drug use just because a lot of times we know that other um activities go along with the use of drug abuse so that will conclude the neurological nervous system review