TEST 4 BRAIN ANAT & PHYS Flashcards
What divides the L hemisphere from the R hemisphere of the brain?
Longitudinal fissure
Wide, deep separation of the brain tissue
Fissure
Infolding on the surface of the brain
Sulcus (sulce)
Upfolding on surface of the brain
Gyrus (gyri)
Separates the frontal lobe from the parietal lobe on each side of the brain
Central sulcus
Locations of the primary MOTOR cortices on each side of the brain
Precentral gyrus (gyri)
Location of the primary SENSORY cortices on each side of the brain
Postcentral gyrus
What divides the parietal and occipital lobes from each other?
Division based off of function, NO anatomic demarcation that separates them
Separates temporal lobe from the frontal lobe and the temporal lobe from most of the parietal lobe
Lateral Fissure
This is below the hemispheres of the brain, composed of tracts. It connects the R and L hemispheres so that each side of the brain knows what the other side is doing
Corpus callosum
Just the below the corpus callosum is the lateral ________ where CSF is.
Lateral ventricle
Most inferior part of the brain stem
Medulla
The opening below the medulla that separates most inferior brainstem to most superior SC
Foramen magnum.
What 3 structures compose the Brainstem?
Midbrain (mesencephalon)
Pons
Medulla oblongota
What 2 structures compose the Diencephalon
Thalamus
Hypothalamus
There are both ascending and descending pathways that MUST pass through the medulla to get info to higher brain centers and back to SC/skeletal muscle. TRUE/FALSE
TRUE
Where are the decussation of the pyramids located
Anterior/inferior surface of the medulla
This is where descending motor pathways cross over to the other side of the SC. Responsible for L side of brain controlling R side of body visversa
Decussation of the pyramids
About _____% of descending motor pathways will cross over to the other side of the SC when they get to the decussation of the pyramids
85%
Located in the medulla, recieve input from the inner ear and play a role in maintaining balance
Olives
Where are the inspiratory and expiratory centers located in the brainstem?
Medulla
Nerve cell bodies (nuclei) located in the medulla
CN IX. glossopharyngeal X. vagus XI. Spinal accessory XII. Hypoglossal
These nuclei are related to CN IX and X, and play a role in the baroreceptor reflex.
Nucleus Solitarius
Nucleus Ambiguus
Where do we find the baroreceptors for CN 9 and 10?
IX (glossopharyngeal): carotid sinuses; bifurcation of the internal carotids
X (vagus): Aortic arch
What activates the baroreceptors?
Increase in blood pressure
Increase in BP = activated baroreceptors = increase in ________transmission through the __________ portions of CN IX and X.
Increase in IMPULSE tx through the SENSORY portions of IX and X
As the impulses transmission approaches medulla, the pathways come together to form _________ and enter nucleus _________.
Tractus solitarius and enters nucleus solitarius
When nucleus solitarius activated, sends message to _________ which is the CV output center.
Nucleus ambiguus
When nucleus ambiguus activated, it excites what receptors?
Central Alpha II receptors
When central alpha II receptors are activated, it decreases ________ outflow and increases ________ outflow.
Decreases SNS outflow and increases PNS outflow
What happens with PNS outflow to help bring BP down?
HR decreases
Decreased strength of contraction
Blood vessels dilate
If we have low BP, the baroreceptors and nuclei are NOT excited and we end up having increased ________ outflow.
How does this increase BP?
Increases SNS outflow
HR increases, Contractility increases, and blood vessels constrict
These 3 structures are involved in modulating pain transmission and help decrease the intensity of pain.
- Raphe magnus nucleus
- Reticularis paragigantocellularis
- Periaquaductal gray matter
What type of NT and receptors are abundant at the sites that modulate pain tx?
Endogenous opioids and MU, Kappa, Alpha receptors
All of these autonomic reflexes are mediated through nuclei in the medulla. (5)
CV/vasomotor center Swallowing Vomiting Coughing Sneezing
This is located in the 4th ventricle and highly related to N/V
Chemoreceptors trigger zone (CTZ)
The CTZ is located OUTSIDE/INSIDE the BBB and comes DIRECTLY/INDIRECTLY in contact with CSF.
CTZ is OUTSIDE the bbb
DIRECTLY in contact with CSF
Any noxious stimuli to the CTZ leads to DECREASED N/V. TRUE/FALSE
FALSE
Any noxious stimuli leads to N/V
What type of drugs are directed at receptors in the CTZ?
Antiemetics
There are only ascending pathways that cross through the Pons. TRUE/FALSE
FALSE
Both ascending and descending tracts pass through the pons.
Tracts that connect the cerebrum to the cerebellum are here
Pons
Coordination of what two parts of the brain lead to coordinated skeletal muscle movement
Cerebrum and cerebellum
This has to do with conscious regulation of skeletal muscle movement
Cerebrum
Has to do with unconscious coordination of skeletal muscle movement
Cerebellum
Nuclei for which CN are located in the pons?
V: trigeminal
VI: abducens
VII: facial
VIII: vestibulocochlear
The pneumotaxic respiratory center is located here
Pons
Site for NE synthesis and secretion in the pons
Locus ceruleus
Locus cereleus is part of what system that has to do with awakeness, alertness, attentiveness.
Reticular activating system (RAS)
Midbrain contains the nuclei for what CN?
III: oculomotor
IV: trochlear
Nuclei for CN III - XII are all located in what structure?
Brainstem
Midbrain is divided into that two structures? (Roof and floor of midbrain)
Tectum (roof)
Tegmentum (floor)
What are the 4 twin bodies located in the tectum of the midbrain?
Corpora quadrigemina
- 2 superior colliculi
- 2 inferior colliculi
This part of the corpora quadrigemina receives sound impulses from the inner ear
Inferior colliculi
Where does the inferior colliculi send sound impulses after received
Superior colliculi
Part of the corpora quadrigemina that is for visual tracking of an object. Uses impulses from eyes, skin and cerebrum.
The 2 superior colliculi
Who is an example of someone who has very well developed superior colliculi?
MLB hitter
ASCENDING tracts pass through here after passing through the medulla an pons, before they get to the cerebrum.
Tegmentum (floor of midbrain)
This is the origin of the rubrospinal tract, has to do with unconscious coordination of movements.
Red nuclei
What animal has highly developed red nuclei?
Red nuclei
Origin of the nigrostriatal tract, part of the basal nuclei
Substantia Nigra
Red nuclei/rubrospinal tract, substantia nigra are located where in the brain?
Tegmentum of the midbrain
These are descending tracts that connect the cerebrum to the SC, located in the midbrain.
Cerebral peduncles
The nuclei of the RAS are scattered widely throughout the brainstem. TRUE/FALSE
TRUE
RAS receives impulses from nerves that innervated the face. (Eyes, skin, ears, nose, etc.) TRUE/FALSE
TRUE
These two things make up the medullary respiratory center
Medullary inspiratory center
Medullary expiratory center
Part of control of ventilation in the pons of the brainstem
Pontine pneumotaxic center
The cells that compose the medullary insp center SPONTANEOUSLY generate AP or are spontaneously active. TRUE/FALSE
TRUE
MIC sends impulse to the phrenic nerve that innervates the ___________ creating longitudinal distance in the lungs.
Diaphragm
MIC also synapses with intercostal nerves that innervates ___________ intercostal muscles and pull the ribcage _______ and _______ creating anterior and posterior size of the lungs.
Intercostal nerves activate EXTERNAL intercostal muscles that pull the ribcage UP and OUT.
As the size of the lungs increases, the volume of the lungs increases, which INCREASES/DECREASES intrapulmonary pressure
Decreases intrapulmonary pressure
When does air enter the lungs?
When does air movement stop?
When intrapulmonary pressure is less than atmospheric pressure, goes with gradient
Stops when pressure equilibrates.
During normal quiet breathing expiration is an active process. TRUE/FALSE
FALSE
It is a passive process
The MIC has a collateral axon to the ________ that sends impulses down to MIC to stop sending AP
Pontine pneumotaxic center
When MIC is not activated, then diaphragm is no longer activated, so the muscle does what to decrease the longitudinal size of the lungs
Domes up/relaxes
MIC not activated, so external intercostals are not active, so they do what to decrease ant/post size of lungs
Pulled down and in
As lung size decreases, intrapulmonary pressure DECREASES/INCREASES.
INCREASES
When does air exit the lungs, according to pressures?
When intrapulmonary pressure exceeds atmospheric pressure
This is ONLY active during a forceful expiration; in the medullary respiratory center.
Medullary expiratory center
Ex) bday candles
MEC synapses with the intercostal nerves that innervate the __________ intercostal muscles
Internal intercostal muscles
When internal intercostal muscles are activated what happens to the ribs?
Causes what to happen to the size and intrapulmonary pressure?
Pulled further down and further in
which decreases size of the lungs, and increases the intrapulmonary pressure to exert a forceful exp
We can increase/decrease ventilation by higher brain centers, just by thinking about it. TRUE/FALSE
TRUE
Located in the medulla, they monitor the pH of the CSF; indirectly measures CO2 levels.
Central medullary chemoreceptors
An INCREASE/DECREASE in CO2 causes excitation of central medullary chemoreceptors
INCREASE
What happens to ventilation and pH when central medullary chemoreceptors are excited?
Increases rate and depth of ventilation, which blows off CO2 and decreases CO2 content and the pH of the CSF and receptors are no longer excited.
Where are peripheral chemoreceptors located; primarily monitor the PO2 of blood.
Bifurcation of the carotids and aortic arch
What excites peripheral chemoreceptors?
When PO2 gets below ~50-60
Peripheral chemoreceptors send a message to the MIC that INCREASES/DECREASES rate and depth of ventilation.
INCREASES
This reflex has to do with stretch receptors in the lungs that prevent overinflation of the lungs
Hering-brewer reflex
Increased muscle activity and Pain both INCREASE/DECREASE rate/depth of ventilation
INCREASE
Largest portion of the diencephalon
Thalamus
4 components of the diencephalon
Thalamus
Subthalamus
Epithalamus
Hypothalamus
Located between the 2 lobes of the thalamus
3rd ventricle of the brain
Why is the thalamus considered the “relay center”?
Where almost all sensory input arrives/stops before information is sent to higher brain centers
The thalamus INTERPRETS the sensory input that arrives. TRUE/FALSE.
FALSE
It just tells which area of the brain the sensation should be sent to, it does not interpret it.
Located on the thalamus, receive input form CN II (optic) visual pathways before transferred to higher brain centers.
Lateral geniculate bodies
Also located on the thalamus, and receive CN VIII (vestibulocochlear) auditory pathways before transferred to higher brain centers
Medial geniculate bodies
The thalamus plays a minor role in our UNCONSCIOUS response to pain and suffering. TRUE/FALSE
FALSE.
Plays a MAJOR role in our response to pain and suffering.
The subthalamus is one component of the ________ nuclei
Basal nuclei
What two structures compose the epithalamus
Habenular nucleus
Pineal body
Receives lots of input from CN I (olefactory) fibers, and lays a role in the limbic system; especially our emotional/visceral gut response to odors.
Habenular nucleus of the epithalamus
Where melatonin is secreted from
Pineal body
Melatonin is produced during ________ and suppressed during ______. Can be highly associated with ________.
Produced in darkness, suppressed in light.
Can be associated with depression.
Main fxn of the hypothalamus
Regulate the activity of the pituitary gland
How is the hyothalamus connected to the pituitary gland?
Infundibulum (stalk)
Connects the hypothalamus to the anterior pituitary
Hypothalamohypophyseal portal system
Two capillary networks connected by a vein.
Portal system
Another name for anterior pituitary
Adenohypophysis
Hypothamohypophyseal portal system allows _______ to be transported from hypothalamus to the anterior pituitary to regulate synthesis and secretion of the ant pit ______.
Hormones; hormones
Growth hormone releasing hormone produces what hormone from the anterior pituitary
Growth hormone synthesis and secretion
Secreted from the hypothalamus and causes inhibition of growth hormone syn/sec from the ant pit
Growth hormone inhibiting hormone or somatostatin
Thyroid stimulating hormone releasing hormone = what hormone from the ant pit
Thyroid stimulating hormone synthesis and secretion
TSH stimulates receptors in the thyroid to produce what?
T3 and T4
Adrenocorticotropic hormone releasing hormone = syn/sec of what hormone in the ant pit
ACTH
Where are the primary receptors for ACTH, and what is released from this area.
Adrenal cortex
Primarily cortisol, also aldosterone and some androgens
What 2 hormones are syn/sec in response to gonadotrophin releasing hormone from the hypothalamus
Follicle stimulating hormone (FSH)
Luteinizing hormone (LH)
Target cell receptors in women for FSH and LH?
Men?
What hormones does it regulate in women/men?
Women: ovaries, regulates estrogen/progesterone
Men: testes, regulates testosterone production
Causes synthesis and secretion of prolactin from the ant pit
Prolactin releasing hormone
Target cell receptors for prolactin in women is in the _______, and causes milk ________.
Breast
Milk production
Secreted from the hypothalamus and inhibits syn/sec of prolactin from the ant pit
Prolactin inhibiting hormone
As the circulating ant pit hormones INCREASE/DECREASE, there is feedback to the hypothalamus to alter its output.
INCREASE
How is the hypothalamus connected to the posterior pituitary gland (neurohypophysis)
Hypothamohypophyseal TRACT
Axons that originate in the hypothalamus and terminate in the post pit make up the hypothamohypophyseal PORTAL SYSTEM. TRUE/FALSE?
FALSE
Axons make up the TRACT.
The supraoptic and paraventricular nuclei are r.t. The ANT/POST pituitary gland?
Posterior
The hormones releases in the post pit are synthesized in the nerve cell bodies in the hypothalamus. TRUE/FALSE.
TRUE
Two corresponding post pit hormones that are synthesized in the hypothalamus, travel down axons and are stored in secretory vesicles at the terminal buton in the post pit.
ADH
Oxytocin
What will cause release of ADH and oxytocin?
APs
ADH also known as
Vasopressin
Vasopressin is released in response to excitation of ___________
Osmoreceptors
Where are osmoreceptors located and what do they monitor?
Located in hypothalamus
Monitor osmolality
Normal body fluid osm?
~300 mosm
What excites hypothalamic osmoreceptors?
Increase in body fluid osmolality (above ~300)
Activated osmoreceptors generates action potentials from what nuclei
Supraoptic and periventricular nuclei
The AP released from osmoreceptors go down hypohypo tract and cause release of _______ from post pit.
ADH
What are the two receptors for ADH and where are they located? What does activation of these receptors cause
V1: vascular smooth muscle; cause vasoconstriction
V2: found in the kidneys; causes increased water reabsorption from kidneys back to bloodstream
Causes uterine contraction and milk expression
Oxytocin
Control of HR, vasoconstriction/vasodilation, urination, peristalsis, and others are under autonomic control. These centers have synapses in this structure from higher brain centers.
Hypothalamus
Where is the swallowing center, and hunger/satiety centers located?
Hypothalamus
If someone were to have a hypothalamic lesion and have uncontrolled shivering/sweating; why is this?
Bc the temperature regulation center is located in the hypothalamus
The hypothalamus coordinates the sleep/wake cycle with the __________ system
Reticular activating system (RAS)
Precentral gyrus is in the _______ lobes
Frontal lobes
Postcentral gyrus is in the ________ lobes
Parietal lobes
This lobe is responsible for complex planning of behavior; moderates our personality, decision making, and social behavior
Prefrontal lobe
_______ prefrontal dom = highly organized, good at math, linear/logical thinking
Left prefrontal dom
__________ prefrontal dominant = musically talented, creative, and artistic
Right prefrontal dominant
Play a role in pre-planning/coordinating muscle movement
Premotor area
Where descending motor pathways originate
Primary motor cortex on the precentral gyrus
The more _______ devoted on the primary motor cortex for that part of the body, the more complex muscle movement occurs there.
More space = more complex movement
Left primary motor cortex innervates the right side of the body. TRUE/FALSE.
TRUE
Initial planning of muscle movement is in the anterior _______ lobe.
Ant frontal lobe
Anterior frontal lobe sends commands to the _______ area
Premotor
This decides what muscles to contract, and sends a message to the primary motor cortex according to the motor homunculus
Premotor area
The motor homunculus activates those descending motor pathways so that they will end in ________
Skeletal muscle movement
Sensory areas are located in the _________ lobes.
Parietal lobes
Sensory impulses are sent here for initial interpretation and localization
Primary sensory cortex
Impulse from the primary sensory Cortex is sent where?
Sensory association area
What does the sensory association area do after receiving an impulse?
Compares current sensation with previous experience
Determines importance of that sensation
Begins process of determining appropriate response
If you have a large amount of space devoted to a certain area of the body on the sensory homunculus, that means that there is a greater conc of ___________ in that area of the body.
Greater conc of sensory receptors
In both the sensory and motor homunculus, where are the upper/lower areas distributed
Upper body/face on lateral side, lower body on medial portion
Sensations form the LEFT side of the body will be transported to the primary sensory cortex on the LEFT side of the brain. TRUE/FALSE
FALSE
Sensations from left will be transported to the right side of the brain
Sensory speech area for understanding/interpreting words; located in parietal lobe.
Wernickes area
Occipital lobe is divided into what two things
Primary visual cortex
Visual association area
Where images are initially sent, where image is seen but not yet interpreted or understood
Primary visual cortex
Where image is compared with previous experience, importance determined, and transmitted to other parts of the brain for final processing, interpretation and what the response should be
Visual association area
When you read words on paper, what is the first step from reading to spoken word?
Image is Projected onto rods and cones of the retina
Those image projected onto the rods and cones of the retina activate what pathways?
CN II (optic)
After impulse sent through CN II fibers, it is sent to the primary visual cortex where it is _______ but not _______.
Image is seen but not identified (in the primary visual cortex)
From the primary visual cortex, the image is sent here, where the image is identified as words.
Visual association area
After the the visual association area identifies an image is words, it is sent to what area to be interpreted?
Wernicke’s area
Which area chooses the individual words and the sequence of those words for a logical thought.
Wernicke’s area
From wernicke’s area, if we are going to speak these words chosen for logical thought, then that information is sent to _________ area to choose the sequence of muscle activity needed to speak the words.
Broca’s area
From Broca’s area (premotor area), the information about what muscles to use to speak chose words is sent to what area ?
Primary motor cortex.
From the primary motor cortex, the information about chosen words and the muscles needed to speak them, activated ____________ motor pathways to the muscles used to speak.
Descending motor pathways
Where sounds are initially sent, basic processing (pitch, volume)
Primary auditory cortex
Compares sound with previous experience with the sound, directs to other parts of the brain for understanding, interpretation and appropriate response
Auditory association area
Sound is first transmitted through what CN fibers
CN VIII (vestibulocochlear)
From CN VIII pathways, the impulse is sent to the __________ where sound is heard but not yet identified
Primary auditory cortex
From the primary auditory cortex, words are sent to the auditory association area where the sound is further processed and identified as a _____.
Word
After the auditory association area identifies a sound as a word, where does it sent the impulse, so that the words can be interpreted, and sequence of words chosen in response
Wernike’s area
What happens to the auditory impulse after the words are interpreted and a response is formulated in the wernicke’s area? (All the way to using the muscles to speak them)
Sent to Broca’s area (muscle activity planned)
Sent from Broca’s to primary motor cortex
Descending motor pathways activated to the muscles used to speak
If wernicke’s are affected in a stroke, will you have receptive aphasia or expressive aphasia??
Both bc wernicke’s are interprets, but its also formulates the sequence of words you speak
If you have a lesion in Broca’s area, will you have receptive or expressive aphasia?
Expressive aphasia, bc wernicke’s is still intact–reception of words and interpretation is not affected
In MOST people wernicke’s and Broca’s are is on the LEFT side of the brain, making L sided strokes more devastating. TRUE/FALSE
TRUE
Purpose is to coordinate with the primary motor cortex and premotor areas to prevent unwanted muscular movements
Basal nuclei
What 3 structures make up the basal nuclei?
Corpus striatum
Subthalamus nucleus
Substantia nigra
The corpus striatum (of the basal nuclei) is made of what two nuclei
Caudate nucleus
Lentiform nucleus
The lentiform nucleus is composed of what two structures
Globus pallidus
Putnamen
The axon from the substantia nigra that synapses with the caudate nucleus is called the ________ tract.
Nigrostriatal tract
What NT is released at the synapse of the nigrostriatal tract to the caudate nucleus?
Dopamine
Dopamine is EXCITATORY/INHIBITORY to the caudate nucleus
Inhibitory
Primary motor cortex also synapses with the caudate nucleus, the NTs here at this synapse are ________.
Are these NTs EXCITATORY/INHIBITORY?
Ach
Glutamate
EXCITATORY
Besides the primary motor cortex, what other area of the brain synapses with caudate nucleus and releases Ach and glutamate?
Globus pallidus
There has to be a very fine balance between excitatory and inhibitory impulses at the caudate nucleus in order to have smooth, coordinated muscle movement. TRUE/FALSE
TRUE
If there was a dopamine deficit or deficiency of dopamine receptors on caudate nucleus, then what would this lead to?
What is a common disease that exhibits this?
Domination of excitatory effects and unwanted muscle movement
Parkinson’s
Parkinson’s symptoms
Stooped posture Pronating/supinating hands Slow, shuffling gait Diff speaking RESTING NON INTENTION TREMORS
Besides L-dopa, what is a procedure used to treat Parkinson’s/essential tremors?
deep brain stimulation (DBS)
How many stages are there for DBS surgery?
What are they?
4 stages
Stage I: bone marker placement/MRI scan
Stage II: electrodes implanted
Stage III: generator implant; wire hook-up
Stage IV: activation and programming of DBS
What type of anesthesia for Stage I DBS sx? LMA or ETT?
General anesthesia
LMA tube unless contraindicated
During stage I DBS, they put ________ markers on the skull that will be used to attach a large contraption that will help guide wires down into the brain.
Bone markers
Why is the MRI scan done in stage I DBS ?
So basal nuclei structures can be identified during sx
In stage II, when the electrodes are implanted, the pt undergoes a general anesthesia craniotomy. TRUE/FALSE.
FALSE
Pt has an AWAKE craniotomy
Why are pts taken off their meds for stage II DBS?
So tremors will be at their worst
During this stage of DBS, only a small amount of remifentanil is given before local injection and the pt is kept awake for the remainder of the procedure
Stage II
What other common medicine must pts be off of in order to complete stage II DBS, that may interfere with their tremors?
BETABLOCKERS
Approximately how far apart is each stage of DBS sx?
One week
The DBS generator is placed in the ______
Chest
DBS generators are good for ______ yrs
5-10 yrs
Both the limbic system and the prefrontal lobes play a role in _______
Motivation
Part of the limbic system that plays a very large role in converting short term memory to long term memory
Hippocampus
We store memories according to our __________ that we experienced when we formed the memory
Emotions
When we recall a memory, emotions associated with those memories will return as well. TRUE/FALSE
TRUE
Plays role in visceral gut response to odors
Habenula
Play a role in human sexuality
Mammillary bodies
This connects various parts of the limbic system, so emotions can be spread throughout the brain
Fornix
What mental illness is especially linked to abnormalities in the limbic system?
Bipolar
Pica is an example of a lesion of the _________
Limbic system
You will be more likely to get angry if you have a lesion to your limbic system. TRUE/FALSE
FALSE
Ppl LOSE their ability to be angry with limbic system abnormality
If lesion of limbic system, how do you respond to dangerous stimuli?
You lose the ability to fear dangerous stimuli
Regulates skeletal muscle movement at the unconscious level
Cerebellum
Also basal nuclei
The cerebellum does not initiate movement, but contributes to coordination, precision, and accurate timing of movement. TRUE/FALSE
TRUE
Receives sensory input from SC and other parts of brain, fine-tunes motor activity
Cerebellum
This informs the cerebellum of desired muscle movement
Collateral from the descending upper motor neuron
Upper motor neuron synapses with lower motor neuron which activates ___________
Skeletal muscle
What two structures sense changes in tension on muscle fibers
Muscle spindles
Golgi tendon bodies
Golgi tendon bodies and muscle spindles send _________ info to the _______ by type A alpha fibers about the actual muscle movement.
Proprioceptive information to the cerebellum
What two types of information does the cerebellum receive, so that it can compare them.
Information about what the desired muscle movement and what the actual muscle movement is
How does the cerebellum let you consciously/unconsciously try to bring about congruence of the desired and actual movement?
Consciously: info back up to brain through thalamus
Unconsciously: extrapyramidal pathway, activates rubrospinal tract
Movement disorder associated with cerebellar lesions
Intention tremors
Test for cerebellar lesion? Does positive or negative indicated a lesion?
Romberg test
Positive indicates lesion
Membranes that surround the brain, protect the brain and anchor the brain in place
Meninges
Meninges surround the brain and the ________
Spinal cord
The meninges of the brain are __________ with the meninges around the SC
Continuous
This is the layer just below the skull
Dura mater
The dura mater is composed of ______ layers
2 layers
When the two layers of the dura mater separate it forms what?
Dural venous sinuses
What is in the dural venous sinuses
CSF
Venous blood
The __________ sinus runs along the entire length of the longitudinal fissure
Superior sagittal sinus
This type of bleed is just above the dura mater and just beneath the skull
Epidural bleed
Potential space below the dura mater, lined with thin film of fluid
Subdural space
Meninge around the brain composed of lots of tiny, fragile blood vessels. (Spider web like appearance)
Arachnoid mater
Since blood vessels of arachnoid mater are very thin and fragile, they bleed easily and can lead to what?
Subarachnoid hemorrhage
What is in the subarachnoid space around the brain and SC?
CSF
This layer is inseparable from the brain, attached directly to the brain.
Pia mater
This dural venous sinus sits right above the corpus collosum
Inferior sagittal sinus
Infolding of the dura mater that separates the L and R cerebral hemisphere
Falx cerebri
Infolding of dura mater that runs between L and R cerebellar hemispheres
Falx cerebelli
Infolding of dura mater between cerebrum and cerebellum
Tentorium cerebelli
Opening in the dura mater to allow passage of the brain stem
Tentorial notch
A SUPRATENTORIAL/INFRATENTORIAL tumor is more lethal.
Infratentorial tumor is more lethal bc there is less space to grow and very vital structures present
What is the difference in the dura mater of the brain and the dura mater of the SC? (2)
Dura mater around the SC is only one layer, instead of two.
Definite space between the dura mater and the vertebral column (epidural space: meds given here)
The corroid plexuses are made up of ________ cells that synthesize the CSF from _________
Ependymal cells
Plasma
These ventricles are located in the medial aspects of the cerebral hemispheres, right below the corpus collosum
Lateral ventricles 1&2
This passageway allows CSF to move from the later ventricles to the 3rd ventricle
Foramen of Monro (intraventricular foramen)
Where is the 3rd ventricle located
In between the 2 lobes of the thalamus
What passageway allows CSF to move from the 3rd ventricle to the 4th?
Aqueduct of sylvius (cerebral aqueduct)
The 4th ventricle is continuous with the ________ that allows CSF to flow the length of the SC.
Central Canal of the SC
What is the only normal way that CSF can move from the ventricular system into the subarachnoid space around the brain and SC?
The 3 openings (foramina) in the 4th ventricle
The CSF production remains constant regardless of the volume and pressure within the ventricular system and subarachnoid space. TRUE/FALSE
TRUE
What causes hydrocephalus?
Accumulation of CSF
Hydrocephalus due to a problem/obstruction within the ventricular system
Noncommunicating hydrocephalus
Hydrocephalus when CSF gets to subarachnoid space but cannot be reabsorbed
Communicating hydrocephalus
Projections from subarachnoid space into venous sinuses that allow for one way flow of CSF into venous sinuses
Arachnoid granulations
Obstruction of ________ can lead to communicating hydrocephalus
Arachnoid granulations
Which ventricles have the largest corroid plexuses and produce the most CSF?
Lateral ventricles
Movement of CSF/blood from dural venous sinuses to R heart
Empty into internal jugulars Jugular foramen Subclavian Superior vena cava R heart
Total amount of CSF is ~ 150ml, how much is in the ventricles and subarachnoid space?
Ventricles ~ 23 ml
Subarachnoid space ~ 127ml
CSF pressure (supine)
50-100 mm H2O
About how much CSF do we produce each day? Reabsorption is about the same.
~500-750 ml
What 3 electrolytes are more abundant in the CSF?
Sodium
Magnesium
Chloride
CSF should be completely clear and colorless. TRUE/FALSE.
TRUE
3 branches of the aorta in order
Brachiocephalic
Left common carotid
Left subclavian
Brachiocephalic artery divides into what two arteries
R Common carotid
R subclavian
R/L common carotids bifurcate into what arteries
Internal/external carotids
R/L subclavian Arteries branch off to make what arteries that carry blood to the brain?
R/L vertebral arteries
What are the 4 arteries supplying blood to the brain?
R/L internal/external carotids
R/L vertebral arteries
Internal/external carotids pass through _______ to get to the base of the Brain
Carotid canal
How do the vertebral arteries get blood to the base of the brain
Foramina of the Transverse processes of the cervical vertebra
Where do the Middle cerebral arteries (internal carotids) provide blood flow to?
Lateral frontal lobes
Lateral parietal lobes
Part of temporal lobes
Anterior cerebral arteries supply blood flow to what areas of the brain?
Prefrontal lobes
Medial frontal lobes
Medial parietal lobes
Vertebral arteries form to make the _______ artery when they get to the brain
Basilar artery
Provides bloodflow to the brainstem and Pons
Pontine arteries coming off of basilar artery
Supply blood flow to the occipital lobes and much of the temporal lobes
Posterior cerebral arteries
The anterior/posterior communicating arteries connect the cerebral arteries to each other and form what structure that allows blood to be diverted around obstructions, so brain is still perfused.
Circle of Willis
What anatomic structures passes right through the circle of Willis ?
Optic Chiasm
Infundibulum (that connects hypothalamus and pituitary)
3 main volumes in the intracranial vault
Brain tissue
Blood
CSF
Abnormal volumes in the intracranial space
Tumor
Cancer
Water
Hemorrhage
Increase of volume in one compartment of the brain must be compensated by decrease in volume of another compartment in order for total brain volume to remain fixed and ICP unchanged
Monro-Kellie doctrine
What can be displaced the easiest out of all the normal volumes in the intracranial space
CSF
The cranial vault has unlimited ability to compensate for increased ICP. TRUE/FALSE
FALSE
Has very limited ability to compensate, fixed compartment
___ ml IC volume means normal IC volume
0 ml
Normal ICP ______ mmhg
~5-15 mmHg
ICP rises dramatically with each ml of volume starting @ _____ ml
5 mL
The brain eats up about ______% of the oxygen delivered through out the body
~20%
The brain MUST have continuous _________ to meet oxygen and glucose needs
Blood flow
Explain coupling of CBF
If one part of the brain is more active, vessels will dilate to improve blood flow to that area, blood will be diverted from areas not as active
Despite changes in BP, CBF remains relatively constant, what is this called?
Autoregulation
CPP equation?
Normal CPP ~_____
MAP - ICP
Normal ~ 50-70
If have a stroke pt, INCREASING/DECREASING blood pressure will maintain CPP in the face of increasing ICP
Increasing BP (MAP)
Increased CO2 vasoconstricts cerebral blood vessels and decreases ICP. TRUE/FALSE
FALSE
Increases CO2 vasodilates and increases ICP
If PaO2 decreases below ~________, vasodilation occurs to increase CBF
50-60
Why do trauma pts need ICP monitored closely
Loss of autoregulation with severe brain injury
FAST/SLOW growing brain tumors have more time to compensate and are LESS fatal
Slow growing brain tumors
How can we decrease in IC volume? (4)
Hyperventilate
Osmotic diuretic (mannitol)
Lumbar drain
Positioning: reverse T
