Exam 3 - Lower Brain Flashcards
The major parts of the brain are:
Brain stem
Cerebellum
Diencephalon
Cerebrum
Brain stem is Continuous with the spinal cord Consists of:
Medulla oblongata
Pons
Midbrain
Posterior to the brain stem
Cerebellum
ser-e-BEL-um = little brain
Superior to the brain stem
Comprises mainly:
Thalamus
Hypothalamus
Diencephalon
dī-en-SEF-a-lon
di = through, encephalon = brain
Diencephalon is Superior to the brain stem and Comprises mainly:
Thalamus
Hypothalamus
It is the largest part of the brain
The cerebrum is supported on the diencephalon and brain stem
It is the largest part of the brain
se-RĒ-brum = brain
The cranial meninges are continuous with the spinal meninges of the same name, and have the same basic structure:
Dura mater (outer) Arachnoid mater (middle) Pia mater (inner)
The cranial dura mater has two layers, whereas the spinal dura mater has only one
The cranial dura mater consists of:
An external periosteal layer formed by the periosteum covering the internal surface of the cranium
An internal meningeal layer that is continuous with the dura mater covering the spinal cord
The two layers are fused together except where they separate to enclose the dural venous sinuses that drain blood from the brain into the internal jugular vein
YUP
An _______ formed by the periosteum covering the internal surface of the cranium
external periosteal layer
An ________ that is continuous with the dura mater covering the spinal cord
internal meningeal layer
Extensions of the dura mater separate parts of the brain:
Falx cerebri separates the two hemispheres (sides) of the cerebrum
Falx cerebelli separates the two hemispheres of the cerebellum
Tentorium cerebelli separates the cerebrum from the cerebellum
_____ separates the two hemispheres (sides) of the cerebrum
Falx cerebri
_____ separates the two hemispheres of the cerebellum
Falx cerebelli
_____ separates the cerebrum from the cerebellum
Tentorium cerebelli
Although the adult brain is only about 2% of the total body weight, it consumes about 20% of the oxygen and glucose when the body is at rest
Neurons synthesize ATP almost exclusively from glucose
Virtually no glucose is stored in the brain
The brain therefore requires a virtually uninterrupted flow of blood to it, and that blood must have sufficient glucose
Neuronal respiration
A blood-brain barrier (BBB) protects brain cells from harmful substances and pathogens by preventing many such substances from entering the brain
The BBB can be broken down or disrupted by trauma, certain toxins, and inflammation
Some parts of the brain lack the blood-brain barrier:
The pineal gland, pituitary gland, and hypothalamus (median eminence of hypothalamus) secrete hormones directly into the bloodstream. The area postrema (of the fourth ventricle in the medulla) senses toxins in the blood, that the blood-brain barrier protects other parts of the brain from; it controls vomiting
Blood-brain barrier
Cerebrospinal fluid (CSF) is a clear, colorless liquid that . . .
Protects the brain and spinal cord against chemical and physical injuries
Carries oxygen, glucose, and other needed chemicals from the blood to neurons and neuroglia
Continuously circulates through cavities in the brain and spinal cord, and around the brain and spinal cord in the subarachnoid space (between the arachnoid mater and the pia mater)
Ventricles are four CSF-filled cavities within the brain
The lateral ventricles together comprise the…
A thin membrane called the _____ separates the lateral ventricles
The third ventricle is a narrow cavity surrounded by the right and left halves of the ____
The fourth ventricle is between the _____
first and second ventricle
septum pellucidum
thalamus
brain stem and the cerebellum
CSF contribution to homeostasis:
______, by serving as a shock-absorbing medium that protects the tissue of the brain and spinal cord from physical jolts; CSF also buoys the brain, causing it to “float” in the cranial cavity
______, by providing an optimal ionic composition chemical environment for accurate neuronal signaling
______, through acting as a medium for exchange of nutrients and waste products between the blood and nervous tissue
Mechanical protection
Chemical protection
Circulation
CSF contribution to homeostasis:
Mechanical protection
Chemical protection
Circulation
Production of CSF:
1) CSF is produced by the….
2) These are networks of capillaries covered by ____ that form CSF from….
3) The ependymal cells are joined by tight junctions, thereby preventing materials from leaking between the cells, and forcing materials that might potentially enter the CSF to be subjected to…
1) …choroid plexuses in the walls of the ventricles
2) ependymal cells; blood plasma by filtration (and some secretion)
3) ependymal cell selectivity
CSF circulation - brain:
1) CSF is formed in the choroid plexuses of each ____
2) It flows into the third ventricle through two small openings called ____
3) The roof of the ____ produces more CSF
4) CSF then flows through the ____ and into the fourth ventricle
5) A choroid plexus in the ____ produces more CSF
CSF circulation - brain:
1) lateral ventricle
2) interventricular foramina
3) third ventricle
4) cerebral aqueduct
5) fourth ventricle
CSF circulation – spinal cord:
From the fourth ventricle, CSF enters the subarachnoid space through three openings in the roof of the fourth ventricle:
a median aperture, and two lateral apertures (a pair—one on each side)
CSF circulation – spinal cord:
Since the subarachnoid spaces of the brain and spinal cord are continuous, CSF also enters the….
It then circulates in the ___ of the spinal cord and the ____ of the brain and spinal cord
spinal subarachnoid space.
central canal and subarachnoid spaces
CSF circulation - brain:
1) CSF is formed in the choroid plexuses of each ____
2) It flows into the third ventricle through two small openings called ____
3) The roof of the ____ produces more CSF
4) CSF then flows through the ____ and into the fourth ventricle
5) A choroid plexus in the ____ produces more CSF
CSF circulation - brain:
1) lateral ventricle
2) interventricular foramina
3) third ventricle
4) cerebral aqueduct
5) fourth ventricle
CSF reabsorption:
CSF is reabsorbed into the blood through _____, which project into the CSF circulatory spaces
It is normally reabsorbed as fast as it is formed, meaning the pressure remains ____
CSF reabsorption:
arachnoid villi
constant
______ is a condition in which excess cerebrospinal fluid builds up in the brain.
The amount of cerebrospinal fluid produced normally equals the amount removed, so the pressure remains the same
Hydrocephalus (hydro = water, cephalus = head)
When excess CSF accumulates in the ____, CSF pressure rises, causing hydrocephalus
If the condition persists the fluid buildup compresses and damages nerve tissue
ventricles
Hydrocephalus can be present at birth or it can develop later. The outlook for people with hydrocephalus varies depending on how soon the condition is diagnosed, whether any other disorders are present and whether treatment is successful. With no treatment, hydrocephalus is nearly always ___.
In babies whose fontanels have not yet closed, the head bulges due to the increased pressure
In adults, hydrocephalus may occur after ___, ___, or ___. It requires immediate intervention because adult skull bones have already fused, and nervous tissue damage occurs quickly
fatal.
head injury, meningitis, or subarachnoid hemorrhage
Hydrocephalus is most often treated with the surgical placement of a _____ that diverts the flow of CSF from a site within the ______ to another area of the body where it can be absorbed as part of the circulatory process.
shunt system
central nervous system (CNS)
A limited number of patients having obstructive hydrocephalus can be treated with a procedure called ____. Aided by a neuroscope, a small hole is made in the floor of the third ventricle, allowing the CSF to bypass the obstruction.
third ventriculostomy
Brain Stem
Continuous with the spinal cord
Consists of:
Medulla oblongata
Pons
Midbrain
A network of interspersed gray and white matter called the _______ extends throughout the brain stem
reticular formation
The components of the brain stem are easily distinguishable in ______ section
longitudinal
The medulla is called the vital brain because it regulates functions upon which life is most dependent, and which occur without our voluntary action:
control of breathing, heart rate, blood pressure, and reflex centers for coughing, swallowing, & vomiting that respond without cognitive processing
vital brain =
medulla oblongata
The medulla begins at the _____, and is a continuation of the spinal cord
foramen magnum
White matter of the medulla contains all ____ and _____ between the spinal cord and other parts of the brain
ascending (sensory) and descending (motor) tracts
The pyramids are bulges of white matter on the anterior where…
… the largest motor tracts pass from the cerebrum to the spinal cord.
The pyramids represent the ?
corticospinal tracts
Most of the axons in the left pyramid cross to the right side ____, and vice versa
(decussate)
This is called decussation of pyramids
Most of the axons in the left pyramid cross to the right side
The medulla has several nuclei (masses of gray matter where neurons form synapses with one another) that control vital body functions:
Cardiovascular center
Medullary rhythmicity area
deglutition center
regulates rate and force of the heartbeat and blood vessel diameter
Cardiovascular center
adjusts the basic rhythm of breathing
Medullary rhythmicity area (part of the respiratory center)
The _____ of the medulla promotes swallowing of a mass (bolus) of food that has moved from the mouth into the pharynx (throat)
deglutition center
promotes swallowing
deglutition center
Medullary nuclei continued:
Other nuclei in the medulla also control…
Coughing, Hicupping, Sneezing…. explain each (not very important)
Coughing, which involves a long drawn and deep inhalation followed by a strong exhalation
Hiccupping, caused by spasmodic contraction of the diaphragm
Sneezing, the spasmodic contraction of breathing muscles that forcefully expel air through the nose and mouth
The ______ of the medulla causes vomiting, the forcible expulsion of the contents of the upper gastrointestinal tract through the mouth
vomiting center (area postrema)
____ pathway from the tongue to the brain, receiving input from taste buds of the tongue
The gustatory nucleus comprises part of the gustatory pathway
_____receive auditory input from the cochlea of the ear, and are therefore part of the auditory pathway
Cochlear nuclei (auditory pathway)
_____ are components of the equilibrium pathway from the inner ear to the brain, receiving sensory information from vestibular apparatus of the inner ear
Vestibular nuclei
_____ is an oval-shaped swelling called an olive
The inferior olivary nucleus within each olive relays impulses to the cerebellum from the (list three)
Lateral to each pyramid
cerebral cortex, red nucleus of the midbrain, and spinal cord proprioceptors that monitor joint and muscle position
The right and left gracile nucleus and cuneate nucleus are in the ____ of the medulla
They are associated with sensations of _______
posterior part
touch, conscious proprioception, pressure, and vibration (First-order sensory neurons)
Posterior nuclei:
______ having their cell bodies in dorsal roots of the spinal cord ascend in the posterior columns to the posterior nuclei of the medulla
There they synapse with second-order neurons having their cell bodies in the correspondingly-named ______
First-order sensory neurons
posterior nucleus of the medulla
Medial lemniscus:
The second-order neurons ascend to the ____ in a band of white matter called the medial lemniscus (lemniscus = ribbon)
The medial lemniscus extends through the _____
The tracts of the posterior columns and axons of the medial lemniscus are collectively known as the _____
thalamus
medulla, pons, and midbrain
posterior column-medial lemniscus pathway
Injury to the medulla:
A hard blow to the back of the head or upper neck can be fatal due to damage to the medulla
Damage to the ____ area is especially serious, and can lead to death
Symptoms of injury to the medulla include ______
medullary rhythmicity
paralysis and loss of sensation on the opposite side of the body, and irregularities in breathing or heart rhythm
The pons (=bridge) is ____ to the medulla
Consists of both nuclei, sensory tracts, and motor tracts (like the medulla)
It is a bridge that connects one part of the brain with another
superior
The pons (bridge) consists of:
The pons consists of both nuclei, sensory tracts, and motor tracts (like the medulla)
Pontine structures:
Connections provided by the pons between parts of the brain are by _____, both _____, and _____
bundles of axons
laterally (connecting the left and right sides of the cerebellum)
vertically (comprising ascending sensory, and descending motor tracts)
_____ relay signals for voluntary movements from their origin in the cerebral cortex to the cerebellum
Pontine nuclei
Pontine Structures:
Nuclei comprising the ___ and ___ help control breathing, in conjunction with the medullary rhymicity area of the medulla
Pontine Structures:
pneumotaxic area and apneustic area
Action of respiratory muscles is controlled by bilateral clusters of neurons in both the medulla oblongata and pons, collectively called the respiratory center and comprising :
Medullary rhythmicity area
Pneumotaxic area
Apneustic area
Action of respiratory muscles is controlled by bilateral clusters of neurons in both the ____ and ____, collectively called the respiratory center and comprising :
medulla oblongata and pons
controls the basic rhythm of respiration, and consists of the inspiratory area and the expiratory area
The medullary rhythmicity area (in the medulla)
When the inspiratory center is active, it generates nerve impulses to the ___ and ___, resulting in inspiration
external intercostal muscles and the diaphragm
During normal quiet breathing, absence of inspiratory impulses from the inspiratory center relaxes inspiratory muscles, resulting in….
exhalation due to passive elastic recoil of the lungs and thoracic wall
Expiratory center neurons are inactive during quiet breathing. During forceful breathing, impulses from the expiratory area are sent to the ____ and ____
Contraction of these muscles causes forceful exhalation
internal intercostal muscles and abdominal muscles.
contraction of internal intercostal muscles and abdominal muscles causes
forceful exhalation
The ___ and ____ coordinate the transition between inhalation and exhalation
pneumotaxic area and the apneustic area
external intercostal muscles and the diaphragm causes
inspiration
turns off the inspiratory area before the lungs become too full
pneumotaxic area
prolongs inhalation by sending stimulatory impulses to the inspiratory area
apneustic area
pneumotaxic area
turns off the inspiratory area before the lungs become too full
apneustic area
prolongs inhalation by sending stimulatory impulses to the inspiratory area
The vestibulocochlear (VIII) nerve has nuclei in two parts of the brain stem,
pons and medulla
The vestibular branch has sensory axons that end in the ______ (although some enter the cerebellum via the inferior cerebellar peduncle)
vestibular nuclei in the pons
The cochlear branch has sensory axons that end in nuclei in the
medulla oblongata
Axons of motor neurons in both branches project from the pons to respective hair cells in the semicircular canals and spiral organ (vestibular and cochlear branches)
True
Midbrain is also termed the ____
It consists of both nuclei and tracts (like the medulla and pons)
mesencephalon
Connects the pons to the diencephalon (thalamus, hypothalamus, etc.)
mesencephalon or Midbrain
It consists of both nuclei and tracts (like the medulla and pons)
Where are the mammillary bodies?
Look at slide 51 of PPT (think it will be a test question potentially)
Mammillary bodies—part of the hypothalamus (of the diencephalon)
_______ are a pair of tracts containing axons of motor neurons that conduct nerve impulses from the cerebral cortex to the spinal cord (corticospinal), medulla (corticobulbar), and pons (corticopontine), as well as axons of sensory neurons that extend from the medulla to the thalamus
The cerebral peduncles (pe-DUNK-uls)
The cerebral peduncles (pe-DUNK-uls) conduct nerve impulses from ____ to ____
(look at slide 52)
from the cerebral cortex to the spinal cord (corticospinal), medulla (corticobulbar), and pons (corticopontine)
as well as axons of sensory neurons that extend from the medulla to the thalamus
contains two pairs of rounded elevations collectively called the corpora quadrigemina (= quadruplets)
The tectum (TEK-tum = roof)
The tectum (TEK-tum = roof) contains two pairs of rounded elevations collectively called the
corpora quadrigemina (= quadruplets)
The _____ passes through the midbrain, connecting the third ventricle above with the fourth ventricle below
cerebral aqueduct
The cerebral aqueduct passes through the midbrain, connecting the…
…. third ventricle above with the fourth ventricle below
Corpora quadrigemina:
Comprise the…
Superior colliculi are reflex centers for visual reflexes and for visually tracking moving objects
Inferior colliculi are part of the auditory pathway as well as reflex centers for auditory stimuli
…superior colliculi and inferior colliculi (ko-LIK-ū-lī ; little hills; singular = colliculus)
Corpora quadrigemina:
_____ are reflex centers for visual reflexes and for visually tracking moving objects
_____ are part of the auditory pathway as well as reflex centers for auditory stimuli
Superior colliculi
Inferior colliculi
Provide some of the neural circuitry that contributes to movement of extrinsic eye muscles for tracking moving images. Circuits extend from retina of the eye to superior colliculi, then to extrinsic eye muscles
Superior colliculi
Various visual reflexes
adjusts size of the pupil?
shape of lens for close and distant viewing?
Pupillary reflex: adjusts size of the pupil
Accommodation reflex: shape of lens for close and distant viewing
This is the center responsible for involuntary turning of the head when an object is detected “out of the corner of the eye”
Superior colliculi
Part of the auditory pathway that relays impulses from hearing receptors in the inner ear to the thalamus
Inferior colliculi
This is the center responsible for the startle reflex, which is the involuntary turning of the head in response to an unexpected sound
Inferior colliculi
startle reflex
Inferior colliculi
“out of the corner of the eye”
Superior colliculi
Superior colliculi
“out of the corner of the eye”
Inferior colliculi is Part of the auditory pathway that relays impulses from…
…hearing receptors in the inner ear to the thalamus
Large darkly pigmented nuclei that release dopamine
Helps control subconscious muscle activities
Loss of these neurons is associated with Parkinson disease
Substantia nigra
Reddish due to rich blood supply and iron-containing pigment in neuron cell bodies
Axons from cerebellum and cerebral cortex synapse with the red nuclei, functioning in the coordination of muscular movements
The rubrospinal tract originates in the red nucleus
The red nucleus controls crawling of babies and swinging of arms in normal walking. It and the rubrospinal tract are primarily involved in control of large muscles of the shoulder and arm, with sparse control over the hands, but not fine control of the fingers which is performed by the corticospinal tract. It does not affect the lower limbs since the rubrospinal tract terminates in the superior thoracic region of the spinal cord
Red nuclei
Axons from cerebellum and cerebral cortex synapse with the red nuclei, functioning in
the coordination of muscular movements
The rubrospinal tract originates in the
red nucleus
crawling of babies and swinging of arms
red nucleus
red nucleus and rubospinal tract primarily involved in…
control of large muscles of the shoulder and arm, with sparse control over the hands, but not fine control of the fingers which is performed by the corticospinal tract.
fine control of the fingers
corticospinal tract.
Why does the red nucleus not affect the lower limbs?
It does not affect the lower limbs since the rubrospinal tract terminates in the superior thoracic region of the spinal cord
Reticular formation :
Much of the brainstem consists of small clusters of neuronal cell bodies along with small bundles of myelinated axons.
True
This fairly extensive region of interspersed gray and white matter in the brain stem is termed the
reticular formation (ret- = net)
The reticular formation comprises both
ascending (sensory) and descending (motor) neurons
The main function of neurons that descend from the reticular formation is to
help regulate muscle tone (the slight degree of contraction that occurs in normal resting muscles)
Part of the reticular formation called the reticular activating system (RAS) consists of
sensory axons that help maintain consciousness and participate in awakening from sleep
consciousness and awakening from sleep
RAS of the reticular formation
Second-largest part of the brain
Has only about 10% of the mass of the brain as a whole, yet has about 50% of all the neurons in the brain
Cerebellum
has 50% of all the neurons in the brain
Cerebellum
Appearance of the cerebellum:
The central constricted area is termed the
vermis (worm)
Appearance of the cerebellum:
The lateral lobes are the….
cerebellar hemispheres (look at slide 63 of PPT)
Appearance of the cerebellum:
The surface has many ridges, or convolutions, called
folia (leaves)
The cerebellar cortex is _____, also exhibiting the foliar ridges
gray matter
The white matter of the cerebellum forms the
arbor vitae (tree of life)
Cerebellar peduncles are bundles of ____ matter comprising axons that ______ between the cerebellum and other parts of the brain
white
conduct impulses
There are three pairs of cerebellar peduncles:
superior, middle, and inferior (arrows in slide 65)
Look at images on slide 66
sweeet
_____ are anterior structures that conduct nerve impulses from the cerebrum to the spinal cord, medulla, and pons.
Cerebral peduncles
______ are posterior structures that conduct impulses between the cerebellum and other parts of the brain.
Cerebellar peduncles
Cerebral peduncles are anterior or posterior?
ANTERIOR = Cerebral peduncles
Cerebellar peduncles are anterior or posterior?
POSTERIOR = Cerebellar peduncles
The main function of the cerebellum is to:
evaluate how well movements initiated by motor areas in the cerebrum are actually being carried out, by comparing what was intended with what is actually being done
When discrepancies are detected it sends feedback signals to motor areas of the cerebral cortex, thereby providing for
smooth, coordinated movement
main regulator of posture and balance
cerebellum
The _____ lobes of the cerebullum mediate unconscious refinements of skeletal muscle movements
anterior and posterior
contributes to equilibrium and balance
floculonodular lobe
is an inability to coordinate muscular movements
Ataxia (“a taxis” meaning without order; incoordination)
Ataxia describes a symptom of incoordination associated with….
…cerebellar infections, injuries, diseases, or degenerative changes
Blindfolded people with ataxia cannot touch the tip of their nose with a finger because they cannot coordinate movement with their sense of where a body part is in space
Speech patterns are abnormal due to uncoordinated speech muscles
Cerebellar damage may also cause staggering or abnormal walking movements
Ataxia
Persons who consume too much alcohol show signs of ataxia because alcohol inhibits activity of the cerebellum
Alcohol overdose also suppresses the ______, and may result in death
medullary rhythmicity area
Diencephalon
Comprises:
Surrounds the ____
Extends from ____ to _____
Diencephalon comprises:
Thalamus
Hypothalamus
Epithalamus
Subthalamus
Surrounds the third ventricle
Extends from brain stem to cerebrum
Comprises Thalamus Hypothalamus Epithalamus Subthalamus
Surrounds the third ventricle
Extends from brain stem to cerebrum
Diencephalon
Diencephalon comprises:
Thalamus
Hypothalamus
Epithalamus
Subthalamus
Makes up most of the diencephalon
Consists of paired oval masses of gray matter organized into nuclei, plus some white matter tracts
Thalamus
Thalamus:
The two halves are connected across the _____ by a bridge of gray matter called the ______
third ventricle
intermediate mass
The ____ is the main relay station for most sensory impulses that reach the primary sensory areas of the cerebral cortex from the spinal cord, the brain stem, or the midbrain
thalamus
Within the thalamus, a sorting out and information editing process occurs wherein impulses having similar functions are grouped together and relayed to the appropriate area of the sensory cortex and cortical association centers
The thalamus also contributes to regulation of autonomic activities and maintenance of consciousness
main relay station for sensory impulses
thalamus
is a thick band of white matter lateral to the thalamus which separates the thalamus and caudate nucleus from the lentiform nucleus
The internal capsule
SORTING OUT INFO and RELAYING
think thalamus
The hypothalamus is a small portion of the _____ located inferior to the thalamus
It controls many body activities, and is a major regulator of homeostasis
diencephalon
are the major component of the mammillary region
They are two, small, rounded projections
Mammillary bodies
serve as relay stations for reflexes related to the sense of smell
Mammillary bodies
The infundibulum is the major structure of concern for the ____
It is the stalk that connects the…..
tuberal region
….pituitary gland to the hypothalamus
infindibulum concern for the….
tuberal region
main visceral control center of the body, and is one of the major regulators of homeostasis. Few tissues in the body escape its influence.
hypothalamus
The hypothalamus has an important involvement with the pituitary gland. The pituitary gland is an endocrine gland that exerts major control over other endocrine glands, so it is the “boss” over much of the endocrine system. The hypothalamus is the “boss” of the pituitary, so in effect it is the “bosses boss.”
We Know Dad
main visceral control center of the body
hypothalamus
Functions of the hypothalamus:
Receptors within the hypothalamus monitor many important parameters of the body… List four mentioned
Receptors within the hypothalamus monitor many important parameters of the body:
Glucose level
Osmotic pressure (osmoreceptors)
Temperature of blood flowing through the hypothalamus
Various hormones (insulin, for example)
Control of the autonomic nervous system
Production of hormones
Regulation of emotional and behavioral patterns
Regulation of eating and drinking
Control of body temperature
Regulation of circadian rhythms and states of consciousness
Functions of the hypothalamus
comprises the habenular nuclei and pineal gland, and is superior and posterior to the thalamus
small epithalamus
are involved in olfaction, especially emotional responses to odors
Habenular nuclei
emotion to odor
Habenular nuclei
secretes the hormone melatonin, and is part of the endocrine system.
pineal gland
is a small area containing tracts and the paired subthalamic nuclei, lying immediately below the thalamus
It works with other structures of the brain to control body movement
subthalamus
subthalamus works with other structures of the brain to control
body movement
separates 1st and 2nd (lateral) ventricles?
septum pallucidum
