Chapter 9 The Nervous System Flashcards
1
Q
At what level does the spinal cord end?
A
The spinal cord ends at L1-L2
2
Q
What is anencephaly?
A
A severe malformation in which the cranial vault is absent and the cerebral hemispheres are either missing or markedly reduced in size
3
Q
What is microcephaly?
A
Means the infant is born with an exceedingly small head. This occurs when there is failure of the cerebrum to develop properly
4
Q
What is hydrocephaly?
A
It literally means “water brain” and occurs within the ventricles
5
Q
What are the different way hydrocephaly may occur?
A
Congenitally or may arise from a variety of causes at any time after birth
6
Q
What happens in hydrocephalic individuals?
A
The ventricles enlarge as a result of a blockage in the flow of CSF at some level
7
Q
What is the most common type of congenital hydrocephalus?
A
Stenosis of the aqueduct of Sylvius, which causes enlargement of the lateral and third ventricles with a normal sized fourth ventricle
8
Q
What happens if the obstruction occurs at the level of the foramen of Monro with hydrocephalus?
A
The lateral ventricles enlarge, leaving the third and fourth ventricles at normal size
9
Q
What are transient ischemic attacks?
A
Mini strokes - they are a temporary interruption of circulation usually caused by arteriosclerotic plaque
10
Q
What are TIAs characterized by?
A
fleeing attacks of faintness, localized paralysis, and aphasia
11
Q
TIAs are a warning of what?
A
A warning sign that a major stroke may be imminent
12
Q
What is the most common head injury?
A
A concussion
13
Q
When does a concussion occur?
A
When there has been violent blow or jar to the head
14
Q
What happens when there has been a violent blow or jar to the head with a concussion?
A
The brain strikes the opposite side of the cranium, resulting in momentary loss of consciousness
15
Q
What symptoms may be associated with a concussion?
A
Transient amnesia, vertigo, nausea, weak pulse, and slow respiration
16
Q
Where do most aneurysms occur?
A
The circle of Willis, in particular the anterior communicating artery and the major subdivisions of the middle cerebral artery
17
Q
What is encephalitis?
A
Inflammation of the brain
18
Q
What is encephalitis almost always caused by?
A
A virus
19
Q
What are many of the viruses that cause encephalitis spread by?
A
Mosquitoes
20
Q
What are the symptoms of encephalitis?
A
Irritability, drowsiness, and headache
21
Q
What is another cause of encephalitis?
A
Herpes simplex 1
22
Q
Although encephalitis is rare, what can happen?
A
It can invade the brain in a susceptible person and result in severe destruction of large areas of the temporal or frontal lobes of the brain
23
Q
What are contra coup lesions?
A
Contusions that occur on the opposite side of the head
24
Q
What is a coup lesion?
A
When the bruise occurs on the same side of the brain as the trauma
25
What is a contusion?
bruises on the surface of the brain and are a result of the brain shifting inside the skull during acceleration and rapid deceleration such as "whiplash" reaction received from a MVA
26
What do contusions result in?
Hemorrhages from small blood vessels, which cause further vessel occlusion and edema
27
What must be closely watched for with contusions?
intracranial pressure
28
What is the nervous system divided into?
The central, peripheral, and autonomic systems
29
What does the central nervous system include?
The brain and the spinal cord
30
What does the peripheral nervous system include?
The cranial and spinal nerves
31
What is the autonomic nervous system divided into?
The sympathetic and parasympathetic systems
32
What is the most highly organized system of the body?
The central nervous system
33
What is the central nervous system also referred to as?
The cerebrospinal system
34
What accounts for about 98% of the entire central nervous system?
The brain
35
About how many neurons are in the brian?
11 billion
36
What is the function of the neurons?
They transmit a message from one cell to the next through a series of axons and dendrites
37
What are the divisions of the brain?
The cerebrum and diencephalon; the brain stem and the cerebellum
38
What does the term brain stem refer to?
The midbrain, pons and medulla
39
How many hemispheres is the cerebrum divided into?
Two hemispheres and are held together by the corpus calosum
40
How many lobes are the two hemispheres of the cerebrum divided into?
Four lobes each named after the cranial bone to which it is related; frontal, occipital, parietal, and temporal
41
What is the entire cerebrum covered with?
The cerebral cortex where the highest level of neural processing takes place including language, memory and cognitive functions
42
What is located below the cerebrum?
The diencephalon which is the part of the brain between the cerebellum and the cerebrum
43
What does the diencephalon contain?
The thalamus and the hypothalamus
44
What is the thalamus?
An importnat relay station, distributing sensory information from the periphery to different regions of the cortex
45
What is underneath the thalamus?
The hypothalamus which contains the third ventricle
46
What does the brian stem consists of?
The midbrain, pons, medulla and the nuclei of the 12 cranial nerves
47
What are the functions of the brain stem?
Many important reflex centers which control vital functions such as heartbeat and respiration. It is also important in regulating levels of consciousness as injury to the brain stem can result in prolonged loss of consciousness or death
48
What is the most posterior part of the brain?
The medulla oblongata
49
Where is the fourth ventricle formed?
In the medulla oblongata. The central canal of the spinal cord enlarges which forms the fourth ventricle
50
What secretes some of the cerebrospinal fluid and contains openings that connect the cavity with the subarachnoid space with the lateral ventricles in the cerebral hemispheres?
The medulla oblongata (fourth ventricle)
51
What connects the cerebellum, the cerebrum and the medulla oblongata?
The pons
52
What is the second largest division of the brain?
The cerebellum, which is latin for "little brain"
53
Where is the cerebellum located?
Just above the medulla, which is overhangs, and beneath the rear portion of the cerebrum
54
Where does the pons lie?
Anterior to the cerebellum and between the midbrain and medulla
55
Where are the ventricles located?
Within the brain hemispheres and are a series of intercommunicating cavities
56
What do the ventricles contain?
CSF and communicate with the subarachnoid space surrounding the brain and spinal cord and with the central canal of the spinal cord
57
How many cerebral ventricles does the ventricular system consists of?
Two lateral ventricles and two others called the third and the fourth ventricles
58
Where are the two lateral ventricles located?
Within the right and left cerebral hemispheres
59
Where are the third and fourth ventricles located?
They are midline
60
What does each lateral ventricle project?
An anterior horn into the frontal lobe of the cerebrum, a posterior horn into the occipital lobe, and an inferior horn into the temporal lobe
61
What is the production of CSF mainly by?
The choroid plexuses of the lateral, third and fourth ventricles
62
What plexuses is the largest and most important?
The plexuses in the lateral ventricles
63
What is the main site of absorption of CSF into the venous system?
Through the arachnoid granulations projecting into the dural venous sinuses
64
What does each lateral ventricle with on the medial side?
The third ventricle by a narrow channel known as the inter ventricular foramina (foramina of Monro)
65
Where is the third ventricle located?
It is a slit-like cavity located in the midline of the skull
66
Where is the third ventricle located?
just below the level of the bodies of the two lateral ventricles
67
What forms the fourth ventricle?
The cavity of the third ventricle extends downward to where it widens posteriorly and laterally
68
What is the connection between the third and fourth ventricles known as?
The aqueduct of Sylvius
69
What are the lateral openings from the fourth ventricle into the subarachnoid cistern known as?
The foramina of Lushcka
70
What does the fourth ventricle connect with through an opening called the foramen of magendie?
The subarachnoid of the cerebellomedullary cistern medially
71
Where does the fourth ventricle communicate with the subarachnoid spaces of the brain and spinal cord?
Through the medial and lateral recess
72
What is the spinal cord directly continuous superiorly with?
The medulla oblongata
73
Where does the spinal cord begin?
The formen magnum and terminates at the junction of the first and second lumbar vertebrae
74
What is the end of the spinal cord called?
The caudal equina, and is located from the second lumbar vertebra to the fifth vertebra
75
What are the three coverings of the spinal cord known as?
The meninges
76
What is the outermost layer and the hardest, toughest, and most fibrous of the spinal cord?
The duramater
77
What is the middle membrane of the spinal cord?
The arachnoid and is much less dense and is web-like in appearance
78
What is the inner layer of the spinal cord?
The pia mater and is the thin, compact membrane that is closely adapted to the surface of the central nervous system. It is very vascular and supplies the blood for the central nervous system
79
When the pia mater and the arachnoid are considered one membrane, what is it called?
The pia-arachnoid or leptomeninges
80
What is the space between the pia matter and the arachnoid referred to?
The subarachnoid space
81
What is the space between the arachnoid and duramater referred to?
The subdural cavity
82
What is the area between the dura matter and the vertebral canal referred to?
The epidural space
83
Where can lumbar punctures be given?
L3-L4
84
What is the peripheral nervous system made up of?
Nerves outside of the brain and the spinal cord
85
How many pairs of spinal nerves are there?
31 pairs
86
How many pairs of cranial nerves are there?
12 pairs
87
What are conveyed through the spinal and cranial nerves?
Both voluntary and involuntary impulses
88
What are the 12 pairs of cranial nerves attached to?
The brain and each leave the skull through a foramen
89
Are the cranial nerves considered voluntary or involuntary?
In general, the cranial nerves are voluntary expect those going to the heart, lungs, salivary glands, stomach and eyes
90
Are the spinal nerves considered voluntary or involuntary
The spinal nerves send involuntary muscle fibers to the smooth muscles of the GI tract, genitourinary tract, and the cardiovascular system
91
What spinal nerves are considered voluntary?
The spinal nerves that go to the muscles of the trunk and extremities
92
What is the autonomic nervous system divided into?
The sympathetic and parasympathetic systems
93
Where does the sympathetic potion arise from?
The thoracic and the first three lumbar segments of the spinal cord
94
Where does the parasympathetic portion arise from?
The third, seventh, ninth, and tenth cranial nerves and from the second, third and fourth sacral segments of the spinal cord
95
The sympathetic system is related to what?
Fight or flight
96
The parasympathetic system is related to what?
Rest or digest
97
What are the cerebrums functions concerned with?
The sensation, thought, memory, judgment, reason, and the initiation or management of the functions that are under voluntary control
98
Where are the optic reflex centers located?
In the midbrain and serves to correlate optic and tactile impulses
99
Where are auditory reflexes located?
In the midbrain
100
What does the midbrain regulate?
muscle tone, body posture and equilibrium
101
What are the chief functions of the central nervous system?
bringing balance, harmony, and coordination to the motions of the body initiated by the cerebrum. To carry out its functions, it acts as an organ of integration and correlation of nerve impulses
102
What are the functions of the hypothalamus?
It controls functions such as eating, drinking and reproduction. It also plays role in behavior, particularly in the expression of emotions such as fear and anger
103
The medulla contains what three vital reflex centers?
The cardiac center which regulates the heartbeat, the medullary rhythmic area which controls the rate and rhythm of breathing and the vasoconstrictor center which regulates the diameter of blood vessels
104
What is the function of the pons concerned with?
The control of facial muscles, including the muscles mastication and the first stages of breathing
105
What does the cerebellum play an important role in?
The control of movement, particularly in the coordination of voluntary muscle activity and in the maintenance of balance and equilibrium. It is particularly sensitive to the effects of severe drunkeness.
106
What does the cerebellum act as to carry out its functions?
An organ of integration and correlation of nerve impulses. It has connections with the motor neurons of the brain and spinal cord, and through these connections the muscles receive impulses to react
107
What area is extremely important for the maintenance of homeostasis
The spinal cord, as it conducts impulses in directions between the brain and the periphery. It also serves to coordinate reflexes
108
What does the autonomic nervous system serve to activate?
The involuntary smooth and cardiac muscles and glands. It also serves the vital system that function automatically, such as the digestive, circulatory, respiratory, urinary, and endocrine systems
109
What does the sympathetic system do?
It dilates the pupils, causes the blood vessels of the skin and viscera to contract so that more blood goes to the muscles, and causes contractions of the sphincters to prevent the emptying of bowels or bladder
110
What does the parasympathetic system do?
It contracts the pupils, dilates the blood vessels when the need has passed, and relaxes the sphincters so that waste can be removed
111
The parasympathetic and sympathetic systems also regulate what?
Body temp, salivary digestive secretions and endocrine glands
112
What does meningitis mean?
Inflammation of the leptomeninges
113
What can meningitis be associated with?
Pneumonia
114
What are symptoms of meningitis?
Fever, headache, muscle pain, and stiff neck
115
What is the most common cause of meningitis?
Bacterial infection
116
How is meningitis diagnosed?
Clinically by evaluation of the CSF
117
What is a frequent lesion of the spinal canal?
Herniation of the pulpy nucleus into the body of a vertebra
118
What is herniation of the pulpy nucleus usually caused by?
Degeneration or tearing of the cartilage plate that separates the nucleus from the vertebral body
119
What may happen when a intervertebral disk protrudes or herniates into the vertebral canal?
It can press on the spinal cord or stretch the nerves known as slipped disk
120
What is the most common cause of herniation of the pulpy nucleus?
trauma
121
What are symptoms of herniation of the pulpy nucleus?
Lower back pain, weakness, and sciatica
122
What does enlargement of the entire ventricular system indicate with hydrocephalus?
An obstruction at the level of the roof of the fourth ventricle, either the formate of magendie or the foramen of luschka
123
What happens are the ventricles expand with accumulated CSF?
The head may enlarge enormously so that normal vaginal delivery of the live infant is impossible
124
What type of hydrocephalus occurs when the ventricles expand with accumulated CSF?
Interna (fluid in the ventricles only) aka noncommunicating
125
Why is internal hydrocephalus considered noncommunicating?
Because an obstruction in the ventricles does not allow the CSF to flow through the ventricles into the subarachnoid space and into the spinal canal
126
In older children and adults, what is most often the cause of hydrocephalus?
Tumors that block the flow of CSF or meningeal scarring secondary to meningitis or hemorrhage. This type of hydrocephalus is not congenital
127
What happens as the tumors grow with hydrocephalus?
They may press on the aqueduct, force the brain stem against the openings, or interfere with the reabsorption of CSF by the arachnoid
128
When the blockage is below the ventricular level with hydrocephalus, so that there is free flow of CSF between the ventricles and the subarachnoid space, or the cause is faulty reabsorption fluid, what is it termed?
external hydrocephalus
129
What happens to the head with external hydrocephalus?
The head does not usually enlarge because the skull is well formed; rather the increased pressure from the accumulated fluid in the ventricles causes pressure atrophy of the surrounding white and gray tissue resulting in mental deterioration
130
What happens when the cranium cannot get any smaller with external hydrocephalus?
There is a compensatory increase in fluid within the spinal canal and the spaces that the atrophy of the brain creates. This is referred to as a compensatory hydrocephalus
131
What happens if the increased pressure is not relieved within the spinal canal with external hydrocephalus?
The brain may herniate toward the foramen magnum and the most effective treatment is a shunt, which is placed either between the lateral ventricles and the cardiac atrium (ventriculoatrial shunt) or between the lateral ventricles and the peritoneum (ventriculoperitoneal shunt)
