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Personal Injury Anatomy-Nervous System

Fairfax Injury Lawyer Brien Roche Addresses Personal Injury Anatomy-Nervous System

Brien Roche

This posting is an overview of the nervous system. The source of the info is a course offered by The Teaching Company and presented by Dr. Anthony Goodman. The course is “Understanding The Human Body:An Introduction to Anatomy and Physiology”.

Within the body there are two systems of communication. The nervous system is like an instant message. The other system is the endocrine system. Also known as the hormone system. This is like the U.S. Mail. It is slower.

Personal Injury Anatomy-Central Nervous System

The central nervous system is the brain and spinal cord. The brain is one of the largest organs in the body. It consists of more than 100 billion cells. In addition it consumes 20% of the body’s blood supply. The brain is surrounded by the skull. There are two layers of bone in the skull. They are separated by air spaces. The largest part of the brain is the cerebrum. This is two hemispheres. Each is then divided into four lobes. The brain has three layers of tissue around it. The outer layer is the dura. Arachnoid is the middle layer. It is spider-like. The lowest layer is the pia mater. This sticks to the brain.

CSF

Within the brain’s open spaces there is cerebral spinal fluid. Also known as CSF. This covers both the brain and the spinal cord. This CSF protects from injury. Also it moves nutrients and waste. The brain separates itself from the rest of the body by the blood-brain barrier. The body lives in a different world than the brain. Hence the barrier. Some drugs do not cross the blood-brain barrier. Call, or contact us for a free consult.

Dura

Sometimes under the dura blood collects. That blood is a subdural hematoma. If that blood causes the hemispheres to shift that is a danger. To remove the blood a surgeon drills a hole in the skull. He sucks the blood out. An epidural hematoma is a collection of blood on the outside of the dura. This is between the dura and the skull. Subarachnoid blood is a tear to the pia mater. This is a big danger.

Circulation

On each side of the neck there are carotid arteries. They carry blood to the brain. In the center of the brain is the Circle of Willis. This is a backup system. If blood is cut off by one artery then the brain can still get the blood it needs from the other arteries.

A short term loss of blood flow to the brain may cause a loss of consciousness. However stoppage of blood flow for one to two minutes may cause brain damage. While stoppage for four minutes causes death.

Glucose helps to keep the brain going. The brain does not store glucose. If there is a drop in the blood glucose level this causes confusion, convulsions, loss of consciousness and finally death.

Reflexes

One old feature of the brain is the “diving reflex”. This cuts off blood flow to all parts of the body other than those body parts that absolutely need it when the body is in very cold water. There are cases where people have survived drownings in very cold water. They may have been under water for as much as 30 minutes. However they have no brain damage. This reflex is a remnant of the primitive brain.

The primitive brain is also seen in instances where you put a baby on a glass surface. The baby will show a startle reflex. This is a result of the fear of falling. However a baby has no fear of falling. That is it never has fallen. The primitive reflex comes from a fear of falling out of trees and having to battle snakes and lizards. That fear of snakes and lizards is with all of us at birth. It is not a learned reaction. Call, or contact us for a free consult.

Babinski

In a baby a test of whether there are breaks in the electrical system is done by scratching the sole of the baby’s foot. The toes should spread apart. In an adult the toes should move towards the center i.e., close. This is called the Babinski reflex.

Although the brain is the center of the nervous system, there are instances where the brain is bypassed. For instance if you touch a hot plate, the reflex will cause your hand to pull away. That series of signals did not go to the brain. The brain learned of it but was not a direct player.

The reflexes within the body are part of the nervous system. Tapping below the knee cap is a simple test. It tests the function of the nerves that travel along the thigh to the spinal cord and then back down to the thigh muscles. Also this tap tests the ham string muscles which have a function of inhibiting. This allows the thigh muscle to do its job. However if the reflex is not working that means the nerve cells (neurons)are not receiving the proper messages .

Baby Brain

A baby’s brain is pretty much fully developed at birth. It still needs more insulation. Likewise a baby’s eyes are fully developed at birth. This is why people frequently comment on the size of the baby’s eyes. The size of the eyes and the size of the head are disproportionate to the rest of the body .

Stem, Cerebellum and Cerebrum

Another part of the brain is the brain stem. It is at the base of the brain. It is right above the spinal cord. The cerebellum controls a number of functions. These include complex motor function and the hypothalamus which is the regulator of stability in the body.

The cerebrum is the highest part of the brain. It controls the highest functions of the brain. The outermost layer is the grey matter. Below that is the white matter. The two hemispheres consist of folds of brain tissue that give the brain greater surface area. This greater surface area is somewhat similar to the need for surface on an elephant. The elephant has large ears because the large surface promotes cooling. The large surface of the brain promotes cooling .

Electricity Keeps Us Going

The nervous system is electrical. It sends electrical signals through chemical ions. Those signals travel in two directions. Each direction has a separate set of nerves. They have a cover that insulates them. This is like the insulation on a copper wire. If that insulation breaks you can have a short circuit. Multiple Sclerosis is this condition. MS is an autoimmune disease. The body attacks itself. As a result this causes nerves to harden because of the lack of sheathing around them.

Personal Injury Anatomy-Peripheral Nervous System

Cells in the central nervous system can be several feet long. They begin at the brain. They go down to the base of the back. There is also a peripheral nervous system. Part of this is voluntary. Part is involuntary. The involuntary nervous system controls fright, fight and flight. This system releases epinephrine in the event of emergencies. It stimulates the digestive tract to promote digestion. It shuts down that digestive system and blood flow to the GI tract where that energy is needed elsewhere because of an emergency.

The voluntary nervous system controls the sensation of pain when you touch a hot plate. Some parts of the body are very specialized as far as sensation. For instance the cornea only has nerve endings for touch. If something touches the cornea it feels it. It pulls away and also tears up to wash away that foreign matter. Likewise the intestines are not sensitive to cutting or burning. However they are sensitive to stretching. The brain has no pain receptors. Therefore a surgeon can operate on the brain while the patient is actually awake without anesthesia .

Ions

Nerve cells are wet. Electrons do not like wetness. As a result electric charges pass through nerve cells through ions (charged particles).

The electrical signals move as a result of the differences in concentration of charged ions. These charged ions are from potassium, sodium and chloride ions. Sodium and chlorine are from salt. Without these charged ions nothing else in the human body works. If you’ve ever been exposed to someone who has had a heat stroke, coincident with attempts to lower the body temperature, electrolytes must be restored. This may be done through salt tablets or other means. Without these conductors of electric current the body does not function.

Electrolytes

Sodium and potassium also have a major role in keeping blood pressure normal. Good sources of sodium are salt, dill pickles, pretzels and bread. Good sources of potassium are sweet potatoes, plain nonfat yogurt, yellow fin tuna, non-cured pork chops, cantaloupe, bananas, leafy green vegetables, root vegetables and fruit from the vine. For most of us a source of sodium is processed food. However processed foods should be avoided in favor of more fresh food. The easy way to define processed food is to think of how many times it’s handled. The handling is with things being added to it. Call, or contact us for a free consult.

People who exert themselves in hot weather or engage in strenuous exercise need to be sensitive to sodium and potassium levels. Losing salt during exercise is a cause of cramping. However consuming too much water causes salt in your body to dilute. If after exercise you notice a white salt on the armpits of your clothing that means you are a salty sweater. You are losing a large amount of salt. You must replace that salt through salt tablets or sports drinks. The latter has electrolytes added to them.

The Brain and The Cord

Synapses

Electrical charges cannot pass through the attachment points of neurons. Those points are called synapses. As a result there are chemicals known as neurotransmitters that receive the signal at one synapse. The body translates that electrical signal into a chemical signal. That signal is sent to an adjoining synapse. These chemicals either promote or retard certain types of actions. Pharmacology over the years has worked wonders in terms of altering these chemicals. This is to either promote certain activities or retard certain activities. Dopamine is a chemical that makes a person feel pleasure. Therefore the release of that chemical in the brain promotes certain behavior. A failure to release retards some actions. Likewise tranquilizers control anxiety. They do so by controlling the amount of certain chemicals in the brain that set the level of anxiety.

Improving the communication at the synapses can also improve learning. As a result the better those channels are working then the more likely it is there will be productive learning.

Networks

The brain consists not only of neurons but also what are called networks of neurons. They work together. For instance a piece of info is not in a single neuron. It is in a network of neurons that interact. Memory is in such networks. Illnesses such as dementia and Alzheimer’s don’t destroy memory. They make it tougher for the networks to work together to retrieve memory. People that are highly creative have broader networks of neurons than do the rest of us. As a result they make quicker and more insightful analyses.

The Cord

The spinal cord is in the vertebrae of the neck, the mid back, the lower back and the sacral area. It is curved in two directions. Like a spring or a shock absorber. It compresses. The coverings of the spinal cord are the same as what you see in the brain. Likewise surrounding the spinal cord is CSF. A spinal tap is literally a tap into the spinal cord area to extract CSF. This fluid gives info about both the brain and the spinal cord. These types of taps are lumbar punctures. The doctor performing them must be careful not to extract too much fluid. Otherwise the brain and the cord can sag. Anesthesia injected into the spinal sac anesthetizes areas below the point of injection. However the effect the anesthesia has is controlled by the position of the body and the law of gravity. Call, or contact us for a free consult.

Injury and Illness

There are many things that damage the central nervous system. Polio is no longer a big threat. Polio is an oral fecal disease which passes from feces to the mouth. It is called the rich man’s disease. When it emerged, poor people immunized themselves from it through exposure. Wealthier people did not immunize themselves because their hygiene was better and they did not get the illness. When they had a lapse of good bathroom hygiene and low resistance to the virus it did its damage.

Lou Gehrig’s disease is a degeneration of neurons. It is fatal.

The breakdown of the fat pads between the vertebrae in the spinal column causes nerve impingement. This also causes paralysis. As part of the aging process these disc pads recede. As a result this promotes the growth of bone spurs in the place of the pads.

One miraculous feature of the nervous system is that nerves have some ability to regenerate at the rate of approximately 1 mm. per day.

Personal Injury Anatomy-The Eye

The eye is part of the nervous system. A feature of vision is judging distance. Binocular vision is a function of both eyes focusing on one object in the distance. Think of the two eyes as being the base of a triangle. The line of sight of each eye to the object are the long arms of that triangle. As those long arms form a smaller angle at the base, the object is closer. As those long arms form a larger angle at the base, the object is more distant. However if only one eye is working the ability to triangulate is lost .

The Structures Of The Eye

The outer surface of the eye is called the conjunctiva. This is a very thin layer. Below that is the cornea. This is the fibrous layer that covers the eye. The cornea help the eye focus. It is a site of surgery wherein the cornea is shaved in order to improve vision. The curved nature of the cornea helps it focus the light. Corneas can be transplanted. The white of the eye gives shape to the globe which contains the iris. This is the colored part of the eye. The pupil is the hole in the donut. Muscles control the lens in the pupil. They change its shape and change the refraction of light.

The retina is at the back of the eye. It is the film in the camera. The retina contains 120 million rods. These are the receptors sensitive to movement and shapes. Also there are 6 million cone shaped receptors in the retina that allow for colored vision. If there is no light there is no color. Instead everything is either grey or black. That’s why at night the best vision is peripheral vision. If you’re a hunter you know that. Therefore if hunting at night, it’s best to look at your prey through your peripheral vision.

By looking at the retina a doctor can tell a great deal about the patient. Diabetes is seen through retinal damage.

On the exterior of the eye there are eyelids. They are windshield wipers. There are also tear ducts that generate fluid to clear particles from the eye. Those tear ducts drain into the nose. This is why when you cry you get a runny nose. Call, or contact us for a free consult.

Motion

If you’ve been sea sick you know your eyes and your brain don’t like an unstable horizon. Your eyes can rotate within your head to keep the horizon flat. When the movement is too much that the eyes can’t rotate then the brain steps in. The brain wants to see a flat horizon. However when it’s not seeing that the result may be sea sickness.

The eyes also like to focus on single objects as opposed to multiple moving objects. If you are on a train passing a series of fixed objects, the eyes will fix on a point in that landscape and follow it until it disappears. They then pick another one. If the eye cannot do this then you should see your eye doctor.

The way that the retina works is that light strikes the retina. Rods and cones activate and that light energy is changed into chemical energy. The chemical energy is vitamin A dependent. That is why you should eat your carrots. That chemical energy is changed into electrical energy. This energy moves to the optic nerve and creates a digital message. As a result the brain converts the message into a picture. It’s much the same as the creation of a picture by a camera .

Illnesses

There are a number of things that go wrong with the eye. Glaucoma is the increased pressure that damages the retina. Cataracts are the clouding of the lens. This may be part of the aging process or a result of diabetes, smoking or a host of other things. Looking at the sun can cause this. However looking at the sun on a clear day is not an activity that your eyes will allow. What is dangerous is looking at the sun on a cloudy day.

Hearing and Balance

Ears are another organ of the nervous system. The ear actually fulfills functions of both hearing and balance. The ear consists of the external ear, the eardrum, the middle ear and the inner ear. Sound waves are the movement of air. This explains why there is no sound in outer space. There is no air.

Airwaves hit the eardrum also known as the tympanic membrane. The eardrum vibrates at the same pitch and amplitude of those airwaves. Pitch is frequency. That is, the number of sound waves that are passing a fixed point over a fixed period of time. Amplitude is the size of the wave. That is, the loudness of the wave. The movement of the eardrum in turn causes movement of three bones that are inside the middle ear. The sound waves transmitted to these bones are then picked up by by a bowl of fluid with small hairs in it. These hairs wave with the motion of the fluid. They transmit those waves to a nerve which then transmits that signal to the brain.

Inner Ear

There is a tube known as the eustachian tube that connects the middle ear to the nose and mouth. This tube is designed to equalize pressure. It’s more efficient at releasing air from the inner ear than it is at drawing air back into the inner ear. When you’re in an airplane that is landing, the external pressure at that point increases putting pressure on the inner ear. The best way to equalize that pressure is to swallow. This allows air to enter the inner ear through the eustachian tube.

Sound and Sight

Helen Keller was once asked which of the two senses that she had lost was the most important. She responded quickly that hearing was by far the most important. It is through hearing that emotion is conveyed.

Hearing loss is an increasing worry because of the prevalence of earphones and earbuds. These devices cause damage to the nerves in the ear. That type of damage is not reversible.

Balance

Another function within the ear is that of balance. You detect what is called static equilibrium (where the body is stationery). You detect dynamic equilibrium where there is a change in motion. However what you cannot detect is uniform motion. This is where there is a constant speed in a constant direction.

There are three small canals in the inner ear that are at right angles to each other. They detect dynamic motion. One of those canals is horizontal, one is vertical and one travels from the front to the back of the body. This provides three axes in order to sense motion. The bowl of fluid that transmits sound waves to the nerves also is the fluid that produces the nerve impulses that tell the brain where the head is. Proprioception is a series of sensors all over the body that tell the brain where the body is. If you spin around in a circle and then stop the fluid in the bowl continues spinning. This tells the brain that there is ongoing movement. In fact there is not. Call, or contact us for a free consult.

Maintaining Balance-Coordinating Info

This vestibular system gathers info from various parts of the body. It uses this info to maintain balance. Lack of balance is sometimes called vertigo or dizziness.  There are related symptoms such as ringing in the ears and hearing your own eyes blink.

This info is gathered from your vision, your body and your inner ears.  All of this info gets put together in the brain. As a result the brain tells us where we are in space and where we are going. 

Balance problems arise from inner ear issues or from brain damage.  An injury to the head may cause increased pressure within the skull which can then influence the balance of fluids within the skull causing vertigo and/or dizziness. Call, or contact us for a free consult.

Memory

Another important part of the nervous system is memory. Some people define insanity as making the same mistake over and over again and expecting a different result. Insanity is a bit broader than that. However loss of memory may be a component of insanity.

The entire brain is involved in the memory process. It is the system of networking that creates memory. A baby’s brain is for the most part fully developed at birth. At birth you have almost all of the neurons that you need. Life events don’t expand the number of neurons. They fill those networks of neurons with memories. Immediate memory is that which occurred within a few seconds of the event. Also there is short-term memory which covers a few seconds to a few minutes. Long-term memory goes beyond that. However only about one percent of conscious info is stored in long-term memory.

Amnesia

Amnesia is the loss of memory. If it is from some traumatic event it is “circumscribed amnesia”. This means that the memory is lost directly before the event and to the extent there is a loss of consciousness, after the event. If the memory returns then the oldest memories return first followed by the newer ones. However complete amnesia involving a loss of all memory is very rare.

Also within the brain is the limbic system which controls emotions. Only mammals have complex emotions.

Call, or contact us for a free consult. For more information on personal injury see the pages on this site. For more information about the nervous system see the pages on Wikipedia 

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Personal Injury Anatomy-Nervous System

Fairfax Injury Lawyer Brien Roche Addresses Personal Injury Anatomy-Nervous System

Brien Roche

This posting is an overview of the nervous system. The source of the info is a course offered by The Teaching Company and presented by Dr. Anthony Goodman. The course is “Understanding The Human Body:An Introduction to Anatomy and Physiology”.

Within the body there are two systems of communication. The nervous system is like an instant message. The other system is the endocrine system. Also known as the hormone system. This is like the U.S. Mail. It is slower.

Personal Injury Anatomy-Central Nervous System

The central nervous system is the brain and spinal cord. The brain is one of the largest organs in the body. It consists of more than 100 billion cells. In addition it consumes 20% of the body’s blood supply. The brain is surrounded by the skull. There are two layers of bone in the skull. They are separated by air spaces. The largest part of the brain is the cerebrum. This is two hemispheres. Each is then divided into four lobes. The brain has three layers of tissue around it. The outer layer is the dura. Arachnoid is the middle layer. It is spider-like. The lowest layer is the pia mater. This sticks to the brain.

CSF

Within the brain’s open spaces there is cerebral spinal fluid. Also known as CSF. This covers both the brain and the spinal cord. This CSF protects from injury. Also it moves nutrients and waste. The brain separates itself from the rest of the body by the blood-brain barrier. The body lives in a different world than the brain. Hence the barrier. Some drugs do not cross the blood-brain barrier. Call, or contact us for a free consult.

Dura

Sometimes under the dura blood collects. That blood is a subdural hematoma. If that blood causes the hemispheres to shift that is a danger. To remove the blood a surgeon drills a hole in the skull. He sucks the blood out. An epidural hematoma is a collection of blood on the outside of the dura. This is between the dura and the skull. Subarachnoid blood is a tear to the pia mater. This is a big danger.

Circulation

On each side of the neck there are carotid arteries. They carry blood to the brain. In the center of the brain is the Circle of Willis. This is a backup system. If blood is cut off by one artery then the brain can still get the blood it needs from the other arteries.

A short term loss of blood flow to the brain may cause a loss of consciousness. However stoppage of blood flow for one to two minutes may cause brain damage. While stoppage for four minutes causes death.

Glucose helps to keep the brain going. The brain does not store glucose. If there is a drop in the blood glucose level this causes confusion, convulsions, loss of consciousness and finally death.

Reflexes

One old feature of the brain is the “diving reflex”. This cuts off blood flow to all parts of the body other than those body parts that absolutely need it when the body is in very cold water. There are cases where people have survived drownings in very cold water. They may have been under water for as much as 30 minutes. However they have no brain damage. This reflex is a remnant of the primitive brain.

The primitive brain is also seen in instances where you put a baby on a glass surface. The baby will show a startle reflex. This is a result of the fear of falling. However a baby has no fear of falling. That is it never has fallen. The primitive reflex comes from a fear of falling out of trees and having to battle snakes and lizards. That fear of snakes and lizards is with all of us at birth. It is not a learned reaction. Call, or contact us for a free consult.

Babinski

In a baby a test of whether there are breaks in the electrical system is done by scratching the sole of the baby’s foot. The toes should spread apart. In an adult the toes should move towards the center i.e., close. This is called the Babinski reflex.

Although the brain is the center of the nervous system, there are instances where the brain is bypassed. For instance if you touch a hot plate, the reflex will cause your hand to pull away. That series of signals did not go to the brain. The brain learned of it but was not a direct player.

The reflexes within the body are part of the nervous system. Tapping below the knee cap is a simple test. It tests the function of the nerves that travel along the thigh to the spinal cord and then back down to the thigh muscles. Also this tap tests the ham string muscles which have a function of inhibiting. This allows the thigh muscle to do its job. However if the reflex is not working that means the nerve cells (neurons)are not receiving the proper messages .

Baby Brain

A baby’s brain is pretty much fully developed at birth. It still needs more insulation. Likewise a baby’s eyes are fully developed at birth. This is why people frequently comment on the size of the baby’s eyes. The size of the eyes and the size of the head are disproportionate to the rest of the body .

Stem, Cerebellum and Cerebrum

Another part of the brain is the brain stem. It is at the base of the brain. It is right above the spinal cord. The cerebellum controls a number of functions. These include complex motor function and the hypothalamus which is the regulator of stability in the body.

The cerebrum is the highest part of the brain. It controls the highest functions of the brain. The outermost layer is the grey matter. Below that is the white matter. The two hemispheres consist of folds of brain tissue that give the brain greater surface area. This greater surface area is somewhat similar to the need for surface on an elephant. The elephant has large ears because the large surface promotes cooling. The large surface of the brain promotes cooling .

Electricity Keeps Us Going

The nervous system is electrical. It sends electrical signals through chemical ions. Those signals travel in two directions. Each direction has a separate set of nerves. They have a cover that insulates them. This is like the insulation on a copper wire. If that insulation breaks you can have a short circuit. Multiple Sclerosis is this condition. MS is an autoimmune disease. The body attacks itself. As a result this causes nerves to harden because of the lack of sheathing around them.

Personal Injury Anatomy-Peripheral Nervous System

Cells in the central nervous system can be several feet long. They begin at the brain. They go down to the base of the back. There is also a peripheral nervous system. Part of this is voluntary. Part is involuntary. The involuntary nervous system controls fright, fight and flight. This system releases epinephrine in the event of emergencies. It stimulates the digestive tract to promote digestion. It shuts down that digestive system and blood flow to the GI tract where that energy is needed elsewhere because of an emergency.

The voluntary nervous system controls the sensation of pain when you touch a hot plate. Some parts of the body are very specialized as far as sensation. For instance the cornea only has nerve endings for touch. If something touches the cornea it feels it. It pulls away and also tears up to wash away that foreign matter. Likewise the intestines are not sensitive to cutting or burning. However they are sensitive to stretching. The brain has no pain receptors. Therefore a surgeon can operate on the brain while the patient is actually awake without anesthesia .

Ions

Nerve cells are wet. Electrons do not like wetness. As a result electric charges pass through nerve cells through ions (charged particles).

The electrical signals move as a result of the differences in concentration of charged ions. These charged ions are from potassium, sodium and chloride ions. Sodium and chlorine are from salt. Without these charged ions nothing else in the human body works. If you’ve ever been exposed to someone who has had a heat stroke, coincident with attempts to lower the body temperature, electrolytes must be restored. This may be done through salt tablets or other means. Without these conductors of electric current the body does not function.

Electrolytes

Sodium and potassium also have a major role in keeping blood pressure normal. Good sources of sodium are salt, dill pickles, pretzels and bread. Good sources of potassium are sweet potatoes, plain nonfat yogurt, yellow fin tuna, non-cured pork chops, cantaloupe, bananas, leafy green vegetables, root vegetables and fruit from the vine. For most of us a source of sodium is processed food. However processed foods should be avoided in favor of more fresh food. The easy way to define processed food is to think of how many times it’s handled. The handling is with things being added to it. Call, or contact us for a free consult.

People who exert themselves in hot weather or engage in strenuous exercise need to be sensitive to sodium and potassium levels. Losing salt during exercise is a cause of cramping. However consuming too much water causes salt in your body to dilute. If after exercise you notice a white salt on the armpits of your clothing that means you are a salty sweater. You are losing a large amount of salt. You must replace that salt through salt tablets or sports drinks. The latter has electrolytes added to them.

The Brain and The Cord

Synapses

Electrical charges cannot pass through the attachment points of neurons. Those points are called synapses. As a result there are chemicals known as neurotransmitters that receive the signal at one synapse. The body translates that electrical signal into a chemical signal. That signal is sent to an adjoining synapse. These chemicals either promote or retard certain types of actions. Pharmacology over the years has worked wonders in terms of altering these chemicals. This is to either promote certain activities or retard certain activities. Dopamine is a chemical that makes a person feel pleasure. Therefore the release of that chemical in the brain promotes certain behavior. A failure to release retards some actions. Likewise tranquilizers control anxiety. They do so by controlling the amount of certain chemicals in the brain that set the level of anxiety.

Improving the communication at the synapses can also improve learning. As a result the better those channels are working then the more likely it is there will be productive learning.

Networks

The brain consists not only of neurons but also what are called networks of neurons. They work together. For instance a piece of info is not in a single neuron. It is in a network of neurons that interact. Memory is in such networks. Illnesses such as dementia and Alzheimer’s don’t destroy memory. They make it tougher for the networks to work together to retrieve memory. People that are highly creative have broader networks of neurons than do the rest of us. As a result they make quicker and more insightful analyses.

The Cord

The spinal cord is in the vertebrae of the neck, the mid back, the lower back and the sacral area. It is curved in two directions. Like a spring or a shock absorber. It compresses. The coverings of the spinal cord are the same as what you see in the brain. Likewise surrounding the spinal cord is CSF. A spinal tap is literally a tap into the spinal cord area to extract CSF. This fluid gives info about both the brain and the spinal cord. These types of taps are lumbar punctures. The doctor performing them must be careful not to extract too much fluid. Otherwise the brain and the cord can sag. Anesthesia injected into the spinal sac anesthetizes areas below the point of injection. However the effect the anesthesia has is controlled by the position of the body and the law of gravity. Call, or contact us for a free consult.

Injury and Illness

There are many things that damage the central nervous system. Polio is no longer a big threat. Polio is an oral fecal disease which passes from feces to the mouth. It is called the rich man’s disease. When it emerged, poor people immunized themselves from it through exposure. Wealthier people did not immunize themselves because their hygiene was better and they did not get the illness. When they had a lapse of good bathroom hygiene and low resistance to the virus it did its damage.

Lou Gehrig’s disease is a degeneration of neurons. It is fatal.

The breakdown of the fat pads between the vertebrae in the spinal column causes nerve impingement. This also causes paralysis. As part of the aging process these disc pads recede. As a result this promotes the growth of bone spurs in the place of the pads.

One miraculous feature of the nervous system is that nerves have some ability to regenerate at the rate of approximately 1 mm. per day.

Personal Injury Anatomy-The Eye

The eye is part of the nervous system. A feature of vision is judging distance. Binocular vision is a function of both eyes focusing on one object in the distance. Think of the two eyes as being the base of a triangle. The line of sight of each eye to the object are the long arms of that triangle. As those long arms form a smaller angle at the base, the object is closer. As those long arms form a larger angle at the base, the object is more distant. However if only one eye is working the ability to triangulate is lost .

The Structures Of The Eye

The outer surface of the eye is called the conjunctiva. This is a very thin layer. Below that is the cornea. This is the fibrous layer that covers the eye. The cornea help the eye focus. It is a site of surgery wherein the cornea is shaved in order to improve vision. The curved nature of the cornea helps it focus the light. Corneas can be transplanted. The white of the eye gives shape to the globe which contains the iris. This is the colored part of the eye. The pupil is the hole in the donut. Muscles control the lens in the pupil. They change its shape and change the refraction of light.

The retina is at the back of the eye. It is the film in the camera. The retina contains 120 million rods. These are the receptors sensitive to movement and shapes. Also there are 6 million cone shaped receptors in the retina that allow for colored vision. If there is no light there is no color. Instead everything is either grey or black. That’s why at night the best vision is peripheral vision. If you’re a hunter you know that. Therefore if hunting at night, it’s best to look at your prey through your peripheral vision.

By looking at the retina a doctor can tell a great deal about the patient. Diabetes is seen through retinal damage.

On the exterior of the eye there are eyelids. They are windshield wipers. There are also tear ducts that generate fluid to clear particles from the eye. Those tear ducts drain into the nose. This is why when you cry you get a runny nose. Call, or contact us for a free consult.

Motion

If you’ve been sea sick you know your eyes and your brain don’t like an unstable horizon. Your eyes can rotate within your head to keep the horizon flat. When the movement is too much that the eyes can’t rotate then the brain steps in. The brain wants to see a flat horizon. However when it’s not seeing that the result may be sea sickness.

The eyes also like to focus on single objects as opposed to multiple moving objects. If you are on a train passing a series of fixed objects, the eyes will fix on a point in that landscape and follow it until it disappears. They then pick another one. If the eye cannot do this then you should see your eye doctor.

The way that the retina works is that light strikes the retina. Rods and cones activate and that light energy is changed into chemical energy. The chemical energy is vitamin A dependent. That is why you should eat your carrots. That chemical energy is changed into electrical energy. This energy moves to the optic nerve and creates a digital message. As a result the brain converts the message into a picture. It’s much the same as the creation of a picture by a camera .

Illnesses

There are a number of things that go wrong with the eye. Glaucoma is the increased pressure that damages the retina. Cataracts are the clouding of the lens. This may be part of the aging process or a result of diabetes, smoking or a host of other things. Looking at the sun can cause this. However looking at the sun on a clear day is not an activity that your eyes will allow. What is dangerous is looking at the sun on a cloudy day.

Hearing and Balance

Ears are another organ of the nervous system. The ear actually fulfills functions of both hearing and balance. The ear consists of the external ear, the eardrum, the middle ear and the inner ear. Sound waves are the movement of air. This explains why there is no sound in outer space. There is no air.

Airwaves hit the eardrum also known as the tympanic membrane. The eardrum vibrates at the same pitch and amplitude of those airwaves. Pitch is frequency. That is, the number of sound waves that are passing a fixed point over a fixed period of time. Amplitude is the size of the wave. That is, the loudness of the wave. The movement of the eardrum in turn causes movement of three bones that are inside the middle ear. The sound waves transmitted to these bones are then picked up by by a bowl of fluid with small hairs in it. These hairs wave with the motion of the fluid. They transmit those waves to a nerve which then transmits that signal to the brain.

Inner Ear

There is a tube known as the eustachian tube that connects the middle ear to the nose and mouth. This tube is designed to equalize pressure. It’s more efficient at releasing air from the inner ear than it is at drawing air back into the inner ear. When you’re in an airplane that is landing, the external pressure at that point increases putting pressure on the inner ear. The best way to equalize that pressure is to swallow. This allows air to enter the inner ear through the eustachian tube.

Sound and Sight

Helen Keller was once asked which of the two senses that she had lost was the most important. She responded quickly that hearing was by far the most important. It is through hearing that emotion is conveyed.

Hearing loss is an increasing worry because of the prevalence of earphones and earbuds. These devices cause damage to the nerves in the ear. That type of damage is not reversible.

Balance

Another function within the ear is that of balance. You detect what is called static equilibrium (where the body is stationery). You detect dynamic equilibrium where there is a change in motion. However what you cannot detect is uniform motion. This is where there is a constant speed in a constant direction.

There are three small canals in the inner ear that are at right angles to each other. They detect dynamic motion. One of those canals is horizontal, one is vertical and one travels from the front to the back of the body. This provides three axes in order to sense motion. The bowl of fluid that transmits sound waves to the nerves also is the fluid that produces the nerve impulses that tell the brain where the head is. Proprioception is a series of sensors all over the body that tell the brain where the body is. If you spin around in a circle and then stop the fluid in the bowl continues spinning. This tells the brain that there is ongoing movement. In fact there is not. Call, or contact us for a free consult.

Maintaining Balance-Coordinating Info

This vestibular system gathers info from various parts of the body. It uses this info to maintain balance. Lack of balance is sometimes called vertigo or dizziness.  There are related symptoms such as ringing in the ears and hearing your own eyes blink.

This info is gathered from your vision, your body and your inner ears.  All of this info gets put together in the brain. As a result the brain tells us where we are in space and where we are going. 

Balance problems arise from inner ear issues or from brain damage.  An injury to the head may cause increased pressure within the skull which can then influence the balance of fluids within the skull causing vertigo and/or dizziness. Call, or contact us for a free consult.

Memory

Another important part of the nervous system is memory. Some people define insanity as making the same mistake over and over again and expecting a different result. Insanity is a bit broader than that. However loss of memory may be a component of insanity.

The entire brain is involved in the memory process. It is the system of networking that creates memory. A baby’s brain is for the most part fully developed at birth. At birth you have almost all of the neurons that you need. Life events don’t expand the number of neurons. They fill those networks of neurons with memories. Immediate memory is that which occurred within a few seconds of the event. Also there is short-term memory which covers a few seconds to a few minutes. Long-term memory goes beyond that. However only about one percent of conscious info is stored in long-term memory.

Amnesia

Amnesia is the loss of memory. If it is from some traumatic event it is “circumscribed amnesia”. This means that the memory is lost directly before the event and to the extent there is a loss of consciousness, after the event. If the memory returns then the oldest memories return first followed by the newer ones. However complete amnesia involving a loss of all memory is very rare.

Also within the brain is the limbic system which controls emotions. Only mammals have complex emotions.

Call, or contact us for a free consult. For more information on personal injury see the pages on this site. For more information about the nervous system see the pages on Wikipedia 

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