Chapter 14: The Brain and Cranial Nerves Flashcards
(173 cards)
1
Q
What does the telencephalon walls and cavity turn into?
A
Walls: Cerebrum
Cavities: Lateral ventricles
2
Q
What does the diencephalon walls and cavity turn into?
A
Walls: Thalamus, hypothalamus, and epithalamus
Cavity - Third ventricle
3
Q
What do the walls and cavities of the Mesencephalon form into?
A
Walls: midbrain
Cavity: aqueduct of midbrain
4
Q
What do the walls and cavity of the metencephalon form into?
A
Walls: pons and cerebellum
Cavity: upper part of 4th ventricle
5
Q
What do the walls and cavity of the myencephalon form into?
A
Walls - medulla oblongata
Cavity - Lower part of 4th ventricle
6
Q
The 4 main parts of the adult brain:
A
- Brainstem
- Cerebellum
- Diencephalon
- Cerebrum
7
Q
This brain structure is continuous with the spinal cord and consists of the medulla oblongata, pons and midbrain
A
The brainstem
8
Q
What are the 3 components/structures of the brainstem?
A
The pons
The Mid Brain
The Medulla OblongataW
9
Q
What main brain structure is posterior the brain stem?
A
The cerebellum
10
Q
What main structure is superior the brain stem?
A
Diencephalon
11
Q
What are the 3 components of the diencephalon in the brain?
A
The thalmus, hypothalmus and the epithalmus
12
Q
This is the largest part of the brain and it is the most superior structure
A
Cerebrum
13
Q
Four principle parts of an adult brain and their sub components
A
*brainstem - pons, midbrain, medulla oblongata
*diencephalon - thalmus, hypothalmus and epithalmus
*cerebrum
*cerebellum
14
Q
Common layers ofthe cranial meninges
A
Dura mater
Arachnoid Mater
Pia Mater
15
Q
What are the two layers of the cranial dura mater?
A
- Periosteal layer (outer)
- Meningeal layer (inner)
16
Q
What are the dural venous sinuses
A
They drain venous blood from the brain and deliver it into the internal jugular veins
17
Q
What are the three extensions of dura mater that seperate parts of the brain
A
- Falx cerebri
- Falx cerebelli
- Tentorium cerebelli
18
Q
What is the function of the falx cerebri?
A
Seperate the two hemispheres of the cerebrum
19
Q
What is the function of the Falx Cerebelli?
A
Seperates the hemispheres of the cerebellum
20
Q
What is the function of the tentorium cerebelli?
A
Seperates the cerebrum from the cerebellum
21
Q
How does the blood mainly flow to the brain?
A
Through the internal carotid and the vertebral arteriesW
22
Q
What do the dural sinuses drain into?
A
The internal jugular vains
23
Q
What is the percentage of body weight represented by the brain?
A
2%
24
Q
What percentage of oxygen and glucose does the brain consume?
A
20%
25
How long does an interurption of blood flow to the brain need to be to start impairing neuronal function?
1-2 minutes
26
How long does the brain need to be totally deprived of oxygen before permanent brain damage develops?
4 minutes
27
Why does the flow of glucose to the brain need ot be continuous?
There is no glucose stores in the brain
28
Symptoms of low blood glucose to the brain?
mental confusion, dizziness, convulsions, and loss of consciousness
29
This strucutre consists mainly of tight junctions that seal together the endothelial cells of the brain blood capillaries and a thick basement membrane that surrounds the capillaries
The blood brain barrier
30
What types of substances are passable through the blood brain barrier by diffusing across the lipi bilayer of endothelial cell plasma membranes?
lipid soluble substances like steroid hormones, alcohol, barbituates, nicotine, and caffeine
water molecules, 02 and C02
31
What substance rapidly cross the BBB by facilitated transport?
A few water soluble substances like glucose
32
What substances often do not pass the BBB
proteins and most antibiotic drugs
33
A clear, colorless liquid composed primarily of water that protects the brain and spinal cord from chemical and physical injuries
Cerebrospinal Fluid
34
This is the space the cerebrospinal fluid is found in the brain and spinal cord
The subarachnoid space
35
The total colume of CSf in an adult
80-150ml
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These cations are found in CSF
Potassium, calcium, magnesium, and sodium
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These anions are found in CSF
Chloride and HC03-
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Other substances found in CSF
Small amount of glucose, white blood cells, protein, urea, lactic acid
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These are basically the first and second ventricles, one found in each brain hemisphere of the cerebrum
Lateral Ventricles
40
This thin membrane separates the lateral ventricles anteriorly
The septum pellucidum
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This brain structure is a narrow, slit like cavity, along the midline superior to the hypothalamus and between the right and left halves of the thalamus
Third ventricle
42
This ventricle is located between the brain stem and the cerebellum
The fourth ventricle
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The three basic functions of the CSF in maintaining homeostasis
1. Mechanical Protection
2. Chemical Protection
3. Ciculation
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One of these on each side of the brain connects the lateral ventricles to the third ventricle
Interventricular foramen
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This structure connects the third ventricle to the fourth ventricle
The mid brain aqueduct
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This structure is a network of blood capillaries in the walls of the ventricles and is where the majority of CSF production occurs
The choroid plexuses
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These neuroglia cells permit selective transport of water and other substances from within the blood capilliaries, into and from the CSF; the substances must pass through the cell bodies
Ependymal
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These structures are found between the ependymal cells that cover the capilliaries of the choroid plexuses and account for the inability of substances to pass directly between the CSF and blood capilliaries
Tight junctions
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The ependymal cells create this barrier that protects the brain and spinal cord from potentially harmful blood born substances
Blood-cerebrospinal fluid barrier
50
Tight junctions of brain capillary endothelial cells creates this barrier
Blood brain barrier
51
The CSF is produced by the choroid plexuses in the lateral ventricles and then flows...
through the interventricular foramina and into the third ventricle
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These are the two narrow, oval openings through which CSF flows from the lateral ventricles to the third ventricle
The interventricular foramina
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This part of the third ventricle adds more CSF production
The choroid plexus of the third ventricle located on its superior surface
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The CSF then travels down through the aqueduct of the midbrain , passing through the midbrain and into...
The fourth ventricle
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In the fourth ventricle, more CSF is added by...
the choroid plexus of the fourth ventricle
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How does CSF enter the subarachnoid space from the fourth ventricle?
There are 3 openings in the fourth ventricle that the CSF enters the subarachnoid space through
57
These are the names of the 3 apertures that are openings in the fourth ventricle for CSF to enter the subarachnoid space
1x Median aperture
2x lateral apertures
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Once the CSF enters the subarachnoid space, where does it circulate in the brain and spinal cord?
Into the central canal of the spinal cord, and around the surface of the brain and spinal cord in the subarachnoid space
59
WHat is an arachnoid granulation?
A cluster of arachnoid villi that absorb CSF
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These are fingerlike extensions of the arachnoid mater that project into the dural venous sinuses and slowly reabsorb CSF
Arachnoid Villi
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At what rate is CSF typically produced and reabsorbed
20mL per hour so 480mL per day
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What two things remain constant due to simultaneous production and reabsorption of CSF
The volume of CSF and the pressure of CSF
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This is the main location of reabsorption of CSF by arachnoid villi clusters called arachnoid granulations
The superior sagittal sinus
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This is a netlike region of interspersed gray and white matter, extending through the brainstem
The reticular formation
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These are the 3 structures of the brainstem
1. Pons
2. Medulla oblongata
3. Midbrain
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This structure of the brainstem begins at the foramen magnum and extends to the inferior border of the pons; it is continuous with the superior portion of the spinal cord and it forms the inferior portion of the brain stem
the medulla oblongata
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The medullas white matter contains all sensory and motor tracts that extend between:
The spinal cord and other parts of the brain
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These are bulges of white matter on the anterior aspect of the medulla
The pyramids
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The pyramids of the medulla oblongata are formed from what tracts?
The corticospinal tracts that control voluntary movement of the limbs and trunk
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What happens to the corticospinal tracts just superior the junction where the medulla and spinal cord join?
90% of the corticospinal tract axons of the left pyramid, cross to the right side, and vice versa right to left
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What is the term to describe the crossing over of the corticospinal axons in the pyramid?
Decussation of pyramids
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What structure of the medulla oblongata pyramids explains the voluntary control of each side of the body by the opposite side of the brain?
The decussation of pyramids
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The medulla contains several of these structures that are collections of neuronal bodies within the CNS
Nuclei
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What does some of these nuclei control?
Vital body functions
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What does the cardiovascular (CV) center regulate?
Rate and force of heart beat and diameter of blood vessels
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What does the medullary respiratory center regulate?
Basic rhythm of breathing
77
What center of the medulla controls the reflex for vomitting?
The vomitting center
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This nuceli in the medulla controls the reflex of swallowing when a mass of food has moved from the oral cavity into the pharynx
Deglutition Center
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This reflex is controlled by nuclei in the medulla and involves spasmodic contraction of breathing muscles that forcefully expel air through the nose and mouth
Sneezing
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This reflex is controlled by nuclei in the medulla and involves a long-drawn and deep inhalation and the a strong exhalation that suddenly sends a blast of air through the upper respiratory passages
Coughing
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This reflex is controlled by nuclei in the medulla and involves the spasmodic contractions of the diaphragm that ultimately result in the production of a sharp sound on inhalation
Hiccuping
82
These oval shaped swellings are found just lateral to each medulla pyramid
Olives
83
Where are the inferior olivary nucleus located?
Within the olive, just lateral the pyramids
84
Where does the inferior olivary nucleus receive input from?
The cerebral cortex, red nucleus of the midbrain and spinal cord
85
What do the axons of the inferior olivary nucleus that extend into the cerebellum control?
The regulate the activity of cerebellar neurons
86
These two nuclei are found in the posterior part of the medulla oblongata; they each synapse with the two tracts in the posterior columns of the spinal cord that have similar names; are associated with sensations of touch, pressure, vibration, and conscious proprioception
Gracile nucleus
Cuneate nucleus
87
These two tracts form synapses with the gracile and cuneate nuclei
The gracile and cuneate fasciculus
88
Information travels up the gracile and cuneate fasciculus and then to the gracile and cuneate nuclei. Then postsynaptic neurons relay the sensory information to:
The thalamus on the opposite side of the brain.
89
The sensory information travels the axons to the thalmus in a band of white matter called:
the medial leminscus
90
The medial lemniscus is a white band of matter that travels through:
the medulla, pons and midbrain to the thalamus
91
The posterior column-medial lemniscus pathway is composed of??
The tracts of the posterior columns and the axons of the medial lemniscus
92
What nucleus is a part of the pathway from the tongue to the brain and receives gustatory information from taste buds of the tongue
The gustatory nucleus of the medulla
93
This nuclei of the medulla are part of the auditory pathway from the inner ear to the brain and receive auditory input from the cochlea of the inner ear
Cochlear Nuclei
94
This nuclei of the medulla and the pons is a component of the equilibrium pathway from the inner ear to the brain and receives information associated with equilibrium from proprioreceptors int he vestibular apparatus of the inner ear
Vestibular Nuclei
95
The medulla also contains nuclei associated with these 5 pairs of cranial nerves:
1. vestibulocochlear (VIII) nerves
2. Glossopharyngeal (IX) Nerves
3. Vagus (X) nerves
4. Accessory (XI) Nerves
5. Hypoglossal (XII) nerves
96
This cranial nerve receives sensory input and provides motor output to the cochlea of the internal ear; hearing related impulses
Vestibulocochlear (VIII) nerve (8)
97
This cranial nerve nuclei found in the medulla relays sensory and motor information related to taste, swallowing, and salivation
The glossopharyngeal nerve (IX)
98
This cranial nerve has its nuclei in the medulla that receives sensory impulses from and provide motor impulses to the pharynx, larynx, and many thoracic and abdominal viscera
The vagus nerve (X)
99
The cranial portion of these nerves are part of the Vagus Nerve (X); nuclei in the medulla are the origin for nerve impulses that control swallowing via the vagus nerves
Accessory Nerves (cranial portion) (XI)
100
The nerves associated with these nuclei in the medulla are origin for nerve impulses that control tongue movements during speech and swallowing
The hypoglossal nerve (XII)
101
This brainstem structure lies directly superior to the medulla oblongata and anterior the cerebellum; it is about 2.5cm long and also consists of both nuclei and tracts
The PONS
Also means bridge; it is the bridge that connects parts of the brain with one another
102
What do the bundles of axons in the pons connect or bridge??
The right and lift sides of the cerebellum; some are part of the ascending sensory tracts and descending motor tracts
103
Two major structural components of the PONS
the ventral region
The dorsal region
104
The ventral region of the pons forms:
a large synaptic relay station
105
What are the scattered gray centers in the ventral region of the pons called/
Pontine nuclei
106
What does the numerous white tracts entering and exiting the pontine nuclei do?
They each provide a connection between the cerebral cortex (outer layer) to the opposite hemisphere of the cerebellum
107
What does this complex circuitry of the pontine nuclei and white matter tracts do?
Play an essential role in coordinating and maximizing the efficiency of voluntary motor output throughout the body
108
What is the dorsal region of the pons composed of?
Ascending sensory and descending motor tracts as well as the nuclei of cranial nerves
109
Where are the nuclei of cranial nerves in the pons located
IN the dorsal region
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This structure within the pons coordinates with the medulla respiratory center to help control breathing
the pontine respiratory group
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What four cranial nerves have their nuclei in the pons?
1. Trigeminal nerve s(V)
2. Abducents (VI) nerves
3. Facial (VII) nerves
4. Vestibulocochlear (VII) Nerves
112
These cranial nerves whose nuclei are in the pons, receive sensory impulses for somatic sensations from the head and face and provide motor impulses that govern chewing
Trigeminal (V) Nerves
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This set of cranial nerves has it's nuclei in the pons and provides motor impulses that control eyeball movement
Abducens Nerve (VI)
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This set of cranial nerves has it's nuclei in the pons and receives sensory impulses for taste and provide motor impulses to regulate the secretion of saliva and tears and contraction of muscles of facial expression
The facial (VII) nerve
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This set of cranial nerves has it's nuclei in the pons and receives sensory impulses from and sends motor impulses to the vestibular apparatus and convey impulses related to balance and equilibrium
The vestibulocochlear nerves (VIII)
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What is the mesencephalon?
The midbrain
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Where is the midbrain found?
Between the diencephalon and the pons
118
How big is the midbrain
2.5 cm like the pons
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Another name for the midbrain
mesencephalon
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Where is the aqueduct found
Through the midbrain, connects the third and fourth ventricles
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What, like the pons and medulla oblongata, does the midbrain contain?
nuclei and tracts
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The anterior part of the midbrain contains paired bundles of axons known as
The cerebral peduncles
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What are the 3 axons that the cerebral peduncles consist of?
- corticospinal
- corticobulbar
- corticoponetine
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Corticospinal tracts conduct nerve impulses from the cerebral cortex, to...
The spinal cord
125
Corticobulbar tracts conduct nerve impulses from the cerebral cortex to...
the medulla oblongata
126
The corticopontine tracts conduct nerve impulses from the cerebral cortex to
the pons
127
The poster part of the midbrain that contains four rounded elevations
The tectumT
128
The two superior elevations of the tectum are nuclei called:
superior colliculi
129
What do the superior colliculi serve as centers for?
They serve as reflex centers for certain visual activities.
Responsible for movements of extrinsic eye muscles as well as head, eyes and trunk in response to visual stimuli
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What are the two inferior elevations (tectums)?
Inferior colliculi
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What are the function of the inferior colliculi?
Part of the auditory pathway, relaying impulses from the receptors for hearing in the inner ear, to the brain
132
What two nuclei are responsible for the startle reflex when you are surprised by a loud noise?
The two inferior colliculi
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These nuclei that are large and darkly pigmented, have neurons extending from it to the basal nuclei that help control subconscious muscle activities
Right and lefty Substantia nigra
134
These reddish looking nuclei have rich blood supply and iron containing pigment in their neuronal cell bodies; axons from the cerebellum and cerebral cortex form synapses here and help control muscular movements
Left and right red nuclei
135
This cranial nerve has it's nuclei in the midbrain and provides motor impulses that control eyeball movements
Oculomotor (III) Nerves
136
Some nuclei in the midbrain provides motor impulses that control movement of the eyeball via this cranial nerve
Trochlear Nerve (IV)
137
This is a broad region in the midbrain where white matter and gray matter exhibit a netlike arrangement
The reticular formation
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Where is the reticular formation?
It extends from the superior part of the spinal cord, throughout the brain stem, and into the inferior part of the diencephalon
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What makes neurons in the reticular formation unique
It has ascending and descending neurons
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What is the ascending portion of the reticular formation called?
The reticular activating system (RAS)
141
What does the reticular activating system consist of?
Sensory axons that project to the cerebral cortex both directly and through the thalamus
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What is the most important function of the RAS
Consciousness
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What activates the RAS
visual and auditory stimuli, mental activities, stimuli from pain, touch and pressure receptors; prioperception
144
What can stimulate the RAS to help maintain consciousness?
visual and auditory stimuli, and mental activities
145
What does RAS help maintain?
Arousal, attention, alertness
146
How does the RAS prevent sensory overload??
By filtering out insignificant information so that it does not reach the consciousness
147
What does inactivation of the reticular activating system cause?
sleep
148
What can damage to the RAS cause?
A coma
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What do the descending portions of the RAS have connects to and help regulate?
The cerebellum and spinal cords and helps regulate muscle tone; also helps regular heart rate, blood pressure and respiratory rate
150
What special sense does not provide input to receptors of the RAS
smell
151
This brain structure has a highly folded surface to increase its surface area of its cortex and contains nearly half the neurons in the brain
The cerebellum
152
This deep groove separates the cerebellum from the cerebrum, along with the tentorium cerebelli
Transverse Fissure
153
This is the thin middle portion of the cerebellum seen in inferior or superior views
The vermis
154
These are the two lateral "wings" of the cerebellum seen in superior or inferior views
Cerebellar hemispheres
155
Deep, distinct fissures separate these two sections of each cerebellar hemisphere:
Posterior and anterior lobes
156
The posterior and anterior cerebellar lobes govern what?
subconscious aspects of skeletal muscle movements
157
This cerebellar lobe on its anterior surface contributes to equilibrium and balance
flocculonodular lobe
158
This superficial layer of the cerebellum consists of grey matter in a series of slender, parallel folds called folia
The cerebellar cortex
159
These are tracts of white matter deep to the cerebellar cortex grey matter
Tracts of white matter called Arbor Vitae
160
Deeper to the white matter arbor vitae, are these regions of grey matter that give rise to axons carrying impulses between the cerebellum and other parts of the brain
cerebellar nuclei
161
Three paired bundles of white matter consists of axons that conduct impulses between the cerebellum and other parts of the brain, and attach the cerebellum to the brain stem and are called:
Cerebellar peduncles
- superior, middle and inferior cerebellar peduncles
162
This cerebellar peduncle contains axons that extend from the cerebellum to the red nuclei of the mid brain and to several nuclei of the thalamus
The superior cerebellar peduncle
163
These are the largest cerebellar peduncles and their axons carry impulses for voluntary movements from the pontine nuclei into the cerebellum
The middle cerebellar peduncles
164
The inferior cerebellar peduncle consists of these 5 things:
axons:
1. Spinocerebellar - trunk and limbs
2. vestibular apparatus of inner ear and vestibular nuclei of medulla and pons; info from head
3. inferior olivary nucleus of the medulla and enters the cerebellum to regulate cerebellar activity
4. cerebellum to the vestibular nuclei in medulla and pons
5. cerebellum to the reticular formation
165
The primary function of the cerebellum
Evaluation of how well movements initiated by motor areas in the cerebrum are actually being carried out
166
The cerebellum also:
regulates movements; sends feedback information through the thalamus to the cerebral cortex
regulates posture and balance
correct errors; smooth the movements; and coordinate complex sequences of skeletal muscle contractions
make complicated muscle sequences possible
167
The presence of what suggests that the cerebellum may also have non motor functions such as cognition and language processing; may also play a role in sensory processing
Reciprocal connections between the cerebellum and association areas of the cerebral cortex
168
The three components of the diencephalon
- thalamus
- hypothalamus
- epithalamus
169
This part of the diencephalon makes up about 80% of it, and is about 3 cm in length; and consists of paired oval masses of gray matter organized into nuclei with interspersed tracts of white matter
The thalamus
170
This bridge of gray matter joins the right and left halves of the thalamus in about 70% of brains
The interthalamic adhesion
171
A vertical, y-shaped sheet of white matter that divides the gray matter of the right and left sides of the thalamus
The internal medullary lamina
172
The internal medullary lamina consists of this
myelinated axons that enter and leave the various thalamic nuclei
173
