seminar 5 MG II

8/7/2019 seminar 5 MG II

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The Brain or Encephalon

General Considerations and Divisions.—The brain, is contained within the cranium, andconstitutes the upper, greatly expanded part of the central nervous system. In its early

embryonic condition it consists of three hollow vesicles, termed the hind-brain or rhombencephalon, the mid-brain or mesencephalon, and the fore-brain or prosencephalon; and the parts derived from each of these can be recognized in the adult

Thus in the process of development the wall of the hind-brain undergoes modification to

form the medulla oblongata, the pons, and cerebellum, while its cavity is expanded to form

the fourth ventricle. The mid-brain forms only a small part of the adult brain; its cavitybecomes the cerebral aqueduct (aqueduct of Sylvius), which serves as a tubular

communication between the third and fourth ventricles; while its walls are thickened to form

the corpora quadrigemina and cerebral peduncles. The fore-brain undergoes great

modification: its anterior part or telencephalon expands laterally in the form of two hollowvesicles, the cavities of which become the lateral ventricles, while the surrounding walls form

the cerebral hemispheres and their commissures; the cavity of the posterior part or diencephalon forms the greater part of the third ventricle, and from its walls are developed

most of the structures which bound that cavity.

The Cranial Nerves

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(Nervi Cerebrales; Cerebral Nerves)

There are twelve pairs of cranial nerves; they are attached to the brain and are transmitted

through foramina in the base of the cranium. The different pairs are named from beforebackward as follows:

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1st. Olfactory. 7th. Facial.

2d. Optic. 8th. Acoustic.

3d. Oculomotor. 9th. Glossopharyngeal.

4th. Trochlear. 10th. Vagus.

5th. Trigeminal. 11th. Accessory.

6th. Abducent. 12th. Hypoglossal.

The area of attachment of a cranial nerve to the surface of the brain is termed itssuperficial or apparent origin. The fibers of the nerve can be traced into the substance

of the brain to a special nucleus of gray substance. The motor or efferent cranial nerves

arise within the brain from groups of nerve cells which constitute their nuclei of origin.The sensory or afferent cranial nerves arise from groups of nerve cells outside the brain;

these nerve cells may be grouped to form ganglia on the trunks of the nerves or may be

situated in peripheral sensory organs such as the nose and eye. The central processes of these cells run into the brain, and there end by arborizing around nerve cells, which are

grouped to form nuclei of termination. The nuclei of origin of the motor nerves and the

nuclei of termination of the sensory nerves are brought into relationship with the cerebral

cortex, the former through the geniculate fibers of the internal capsule, the latter throughthe lemniscus. The geniculate fibers arise from the cells of the motor area of the cortex,

and, after crossing the middle line, end by arborizing around the cells of the nuclei of

origin of the motor cranial nerves. On the other hand, fibers arise from the cells of the

nuclei of termination of the sensory nerves, and after crossing to the opposite side, jointhe lemniscus, and thus connect these nuclei, directly or indirectly, with the cerebral

cortex.Stroke

Most strokes are caused by a blockage in an artery that carries blood to the brain. This

can cause that part of the brain to be damaged, and you may lose control of a function

that is controlled by that part of the brain. For example, you could lose the use of an armor leg, or the ability to speak. The damage can be temporary or permanent, partial or

complete. Doctors have found that if you get treatment right away after symptoms start,

there is a better chance of getting the blood moving to your brain, and less chance of

damage.

Symptoms Sudden weakness or numbness of the face, arm or leg on one side of the body

• Sudden dimness or loss of vision, particularly in one eye

• Loss of speech, trouble talking or understanding what others

• are saying

• Sudden severe headache with no known cause

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• Unexplained dizziness, unstable walking or falling, especially along with any of

the other symptoms

Another warning sign of a stroke is called a transient ischemic attack (TIA). A TIA is a"mini-stroke" that can cause the symptoms listed above and may only last a few minutes,

but should not be ignored. People who have a TIA are at greater risk of having a strokelater. Call your doctor immediately if you think you are having a TIA.

Migraine Headaches

Migraine headaches seem to be caused in part by changes in the level of a chemical madein the brain called serotonin. Serotonin plays many roles in the body, and it can have an

effect on blood vessels. When serotonin levels are high, blood vessels constrict (shrink).

When serotonin levels fall, the blood vessels dilate (swell). This swelling can cause painor other problems.

Many things can affect the level of serotonin in your body, including your level of blood

sugar, certain foods and changes in your estrogen level if you're a woman.Possible symptoms of migraines

• Intense throbbing or dull aching pain on one side of your head or both sides

• Pain that worsens with physical activity

• Nausea or vomiting

• Changes in how you see, including blurred vision or blind spots

• Being bothered by light, noise or odors

• Feeling tired and/or confused

• Stopped-up nose• Feeling cold or sweaty

•

Stiff or tender neck • Light-headedness

• Tender scalp

Classic migraines start with a warning sign, called an aura. The aura often involves

changes in the way you see. You may see flashing lights and colors. You may

temporarily lose some of your vision, such as your side vision.

You may also feel a strange prickly or burning sensation, or have muscle weakness on

one side of your body. You may have trouble communicating. You may also feeldepressed, irritable and restless.

Auras last about 15 to 30 minutes. Auras may occur before or after your head pain, andsometimes the pain and aura overlap, or the pain never occurs. The head pain of classic

migraines may occur on one side of your head or on both sides.

Common migraines don't start with an aura. Common migraines may start more slowlythan classic migraines, last longer and interfere more with daily activities. The pain of

common migraines may be on only one side of your head.

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Epilepsy

Epilepsy is a disorder of the brain. People with epilepsy have brain cells that create

abnormal electricity, causing seizures. In some cases, a seizure may cause jerking,uncontrolled movements and loss of consciousness. In other cases, seizures cause only a

period of confusion, a staring spell or muscle spasms.A single seizure is not considered epilepsy. People with epilepsy have repeated episodes

of seizures.Epilepsy is not a mental illness, and it is not a sign of low intelligence. It is also not

contagious. Seizures do not normally cause brain damage. Between seizures, a person

with epilepsy is no different from anyone else.If you have epilepsy, you may want to share the following information with your family,

friends and coworkers. If someone near you has a seizure, use the following general

guidelines:

• Stay calm.

•

Don't move the person to another place.• Don't try to keep the person from moving or shaking.

• Don't try to wake the person by shouting at or shaking them.

• Remove items that could cause injury if the person falls or bumps into them.

• Gently turn the person on his or her side so any fluid in the mouth can safely

come out.

• Never try to force the person's mouth open or put anything in it.

• Place something soft (such as a pillow) under his or her head.

• Most seizures aren't life-threatening. You don't need to call a doctor or an

ambulance unless the person isn't known to have epilepsy or unless the seizurelasts longer than 5 minutes.

•

When the seizure is over, watch the person for signs of confusion. Allow theperson to rest or sleep if he or she wishes.

Cervical Spondylotic Myelopathy (CSM)

Cervical spondylotic myelopathy (CSM) is a compression of the spinal cord in the neck.

(When doctors say the spinal cord is "compressed," they mean it is being pressed and

squeezed.) CSM often affects older adults, but at earlier ages in men than in women.In people with CSM, changes in the bones, disks and ligaments of the spine cause

pressure on the spinal cord. Sometimes bony growths called bone spurs add pressure to

the spine. Some changes are because of normal aging. Some changes are caused by

arthritis of the spine. CSM is the most common spinal cord problem in people 55 years or older in the United States.

Symptoms of CSM may develop slowly. Some symptoms of CSM include:

• Neck stiffness

• Arm pain• Numbness in the hands and weakness of the arms and legs

• Stiff legs

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• Difficulty using your hands or walking steadily

• Loss of bladder or bowel control

Trigeminal Neuralgia

Trigeminal neuralgia is extreme burning, electric or shock-like pain in the face. The paincan be so extreme that it can get in the way of normal activity. Even the fear of oncoming

attacks can be so stressful that performing day-to-day tasks is a challenge.

The pain may last a few seconds or minutes, then ease and then recur. Usually, these

cycles of pain occur for a few days or weeks, and then stop for days, weeks or even years

before returning. Over time, the cycles tend to recur more quickly, with shorter breaks in

between.

A flare sometimes is triggered by very normal activities, such as chewing, smiling,

talking, shaving or brushing your teeth. At times, even the wind on your face can cause

pain to start.

Some people who have trigeminal neuralgia notice numbness or tingling of the face in thedays leading up to an attack.

Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune disease that affects the nervous system.

Normally, antibodies produced by the immune system help protect the body againstviruses, bacteria and other foreign substances. In people who have MS, the immune

system destroys the substance that surrounds and protects your nerve cells – the myelin

sheath.

The job of the nervous system is to send electrical messages back and forth from the

brain to different parts of the body. Normally, the brain quickly sends signals through the

spinal cord and then through nerves that branch out to all organs and body parts. Whenmyelin around nerves is damaged or destroyed, the nerves can’t function properly to

deliver these signals in the right way. This can cause symptoms throughout the body.

MS affects women more than twice as often as men. White (Caucasian) people are morelikely to develop it than people of other races. If someone in your family--such as a

parent or sibling--has MS, you have a greater risk of developing it, too. MS can affect

people of any age, but it often begins between the ages of 20 and 40. If you have another autoimmune disease, such as thyroid disease or Type 1 diabetes, your risk of developing

MS is slightly higher.

Common symptoms include:

• Vision problems, including double vision, blurriness, partial color blindness, eyepain, partial or complete loss of vision in 1 eye

• Thinking and memory problems

• Fatigue

• Muscle weakness, dizziness or tremor

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• Numbness or weakness on one side or the bottom half of your body

• Trouble with coordination and balance

• Loss of bowel or bladder control

• Sensations such as numbness or tingling, "pins and needles"

• Electric-shock sensations caused by moving your head in a certain way

Testing for MSBlood test. Your blood can show signs of other illnesses that cause symptoms similar tothe symptoms of MS.

Neurological tests. Your doctor may want you to see a neurologist who can test howwell your nervous system is working. The tests will look for changes in eye movements,

muscle coordination, weakness, balance, sensation, speech, and reflexes.

Spinal tap (lumbar puncture). A small amount of fluid taken from your spine can show

abnormal amounts of blood cells or proteins associated with MS. A spinal tap can also

rule out a viral infection or other possible conditions.

Magnetic Resonance Imaging (MRI). An MRI can show detailed pictures of the brain

and spinal cord, and if there are any lesions present. However, lesions aren’t always

caused by MS.

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seminar 5 MG II