Brain/CNS Flashcards
6 lobes of the cerebrum
frontal, parietal, occipital, temporal, insular (within the lateral sulcus), limbic (C shaped & circles corpus callosum)
4 main components of the cerebrum
cortex = gray matter - sulcis & gyrus
white matter = primarily axons; corpus callosum & internal capsule
basal ganaglia
ventricles
5 main sulci/fissures
what do they seperate
longitudinal fissure - two cerebral hemispheres
central sulcus - frontal lobe from parietal lobe
lateral sulcus - frontal lobe from temporal lobe
calcarine sulcus - divides medial surface of occipital lobe into upper cuneus & lower lingula
parieto-occipital sulcus - occipital from parietal:: rostral parietal portion from this line = precuneus
uncal herniation
herniation of the uncus (located in the parahippocampal gyrus of the temporal lobe)
herniation under the tentoriu cereblli causes compression of cranial nerve III (occulomotor)
where is the primary motor cortex located?
precentral gyrus - control voluntary movement
where is the primary somatosensory area located
post central gyrus = process somatosensory body information
thalamus
-made up of many cells = thalamic nuclei
acts as a relay station for sensory & motor impulses
–> conscious awareness of specific sensory stimuli
–> important in memory, feelings, and emotions
nucleus ventralis posterolateralis (VPL)
part of the thalamus
processes somatic sensory info from the body and relays it to primary sensory cortex
hypothalamus - what is it/what’s it do
group of cells = hypothalamic nucleus
control/integrate ANS function, control/integrate food intake & endocrine systems
intimately related to the pituitary gland
pineal gland - function & location
located in the epithalamus
regulates ciradian rhythms
what are the two ebroylogical outgrowths of the diencephalon?
optic nerve (CN II) & a portion of the retina
what are the 3 parts of the brain stem
midbrain, pons, medulla
midbrain - location & important surface features
origin of what nerves
located between the diencephalon & the pons
dorsal surface = tectum - 2 superior colliculi & 2 inferior colliculi
ventral surface = cerebral peduncles (or crus cerebri)
origin of CN III & IV
Medulla oblongata - location, features, CN
located between pons and spinal cord
ventral surface = pyramids & olive - connects to the spinal cord & cerebellum (respectively)
CN IX, X & XII
Pons - location, important features, origin of what nerves
located between midbrain & medulla
Ventral surface = basis pontis
Dorsal surface = Cerebellar peduncles
Origin of CN V, VI, VII, VIII
Cerebellum - surface features
vermis & two lateral hemispheres
basis pontis - location, function
ventral surface of pons
fiber tracts interconnecting spinal cord & cerebellum w/ brainstem – corticospinal tracts included
Cerebellar peduncles - location, function
dorsal surface of Pons
white matter bundles that are attachemnts for cerebellum - superior, middle & inferior
Tectum - location, function
Dorsal surface of midbrain
hold 2 superior colliculi & 2 inferior colliculi = reflex centers for head & neck movement in response to vision/auditory
cerebral peduncles (or crus cerebri) - location, function
ventral surface of midbrain
contain corticospinal tract that carries impulses from cortex to pons, medulla & spinal cord
basal ganglia
prominent group of neuronal cell bodies lying deep to thee cortex & subcortical white matter
what is the foramen of monroe?
also called the interventricular foramen; structure through which the lateral ventricle communicated with the third ventricle
how many lateral ventricles are there
2 = one left & one right
what passes through subcortical white matter? via what?
what does white matter contain?
all information entering/leaving the cerebral cortex passes through vis. the corona radiata
white matter contains association fibers: commissural & association fibers
Functions of Association fibers
- general
- long
- short
interconnect various areas of the cortex WITHIN the same hemisphere
Short = connect one gyrus to an adjacent gyrus
Long = connect distant areas of the hemisphere to eachother
what is the superior longitudinal fasiculus (arcuate fasciculus)
what does it connect
a long association fiber that connects the frontal, parietal, and occipital cortices
what is the urnicate fasciculus? what does it connect?
a long association fiber that connects the frontal and temporal lobes
Define commissural fibers - what are the 2 main fibers
fibers that interconnect structures on EITHER side of the hemisphere
- corpus callosum
- anterior commisure
What does the corpus callosum connect?
main anatomical features
interconnects frontal, parietal, and occipital lobes across the hemisphere
rostrum, genu, body, splenium
what does the anterior commissure connect?
connects parts of the two temporal lobes
where is the posterior commissure?
part of the epithalamus found near the base of the pineal gland
function and location of anterior white commissure
within the spinal cord
pain and temperature fibers cross here
corticofugal axons vs. corticopetal axons
- what type of fibers, differences
- example of each
- organized into what
fungal = arise from within cerebral cortex & project to outside targets; ex: corticospinal tract petal = arise outside of cerebrum and project to the cortex; ex: thalamotorical fibers
*these fibers are organized into the internal capsule
Anatomy of the internal capsule
Anterior limb = separates caudate nucleus from putamen & globus pallidus
Posterior limb = seperates thalamus from lenticular nucleus
Genu = located @intersection of anterior & posterior limbs
3 parts of the internal capsule
what do each hold
Anterior Limb - parts of the limbic system
Genu - corticonueclear (corticobulbar) fibers
Posterior Limb - corticospinal tracts
Lesion to the corticonuclear fibers
motor deficits of cranial nerves, primarily hypoglossal & facial nerve
Damage to the posterior limb of the internal capsule
damage causes contralateral hemiplegia
and sensory issues
lesion = combination of motor & sensory deficits seen on the contralateral side of the lesion
what does the internal capsule switch to in the midbrain?
the crus cerebri & the ventral part of the cerebral peduncles
what is the main blood supply to the internal capsule?
what are they prone to?
lenticulostriate arteries
frequently involved in stroke
what is the most frequent spot for stroke?
posterior limb
results in spastic hemiplegia (muscle) & hemianesthesia (sensory)
functions of the CSF
protective cushioning for the brain
provides buoyancy = makes the brain lighter
what cells line the ventricles
ependymal cells
what do the ventricles hold?
who makes it? how much?
CSF
choroid plexus - 500ml/day
what separates the frontal horns of R & L ventricles?
septum pellucidum
what are the 5 parts of the lateral ventricles? Where are the ventricles located?
anterior horn, body, posterior horn, inferior horn, atrium/trigone
within the cerebral hemisphere
where is the 3rd ventricle located
where is the cerebral aqueduct?
where is the 4th ventricle???
within the diencephalon
within the midbrain
within the pons & medulla
what is obstructive hydrocephalus?
increased pressure due to blocking of the cerebral aqueduct
how many openings does the 4th ventricle have?
what does it continue as?
3 openings = foramen Magendie & 2 foramina of Luschka
continues into spinal cord as central canal
What is the flow of CSF?
Lateral ventricle –> 3rd ventricle –> cerebral aqueduct –> 4th ventricle
(via. foramen Monroe)
What is ventriculomegaly?
enlargement of the ventricles caused by a blockage or failure of reabsorption
3 things that can cause hydrocephalus
obstruction of flow, decrease in reabsorption, excess CSF production (rare)
Noncommunicating vs. communicating hydrocephalus
non= obstruction of flow with ventricles = ventricles can no longer communicate with each other
comm = impaired reabsorption in arachnoid granulations or obstruction of flow in subarachnoid space = ventricles can still communicate with each other
hydrocephalus ex vacuo
seemingly enlarged ventricles in older individuals because their brain is smaller — their ventricles actually aren’t smaller
symptoms of hydrocephalus
headache, nausea, vomiting, cognitive impairment, decreased consciousness, papilledema, decreased vision, sixth nerve palsy
ventricular dilation –> may compress brain tissue and lead to symptoms related to the part being compressed
what is the attachment for the falx cerebri?
crista galli
what contains the inner ear structures
petrous part of the temporal bone
what transmit the olfactory nerves
cribriform plate of ethmoid with cribiform foramina (part of the anterior cranial fossa)
what fossa contains the brainstem & cerebellum?
posterior cranial fossa
3 main functions of the meninges
- protect the underlying brain and spinal cord
- provide supporting framework for arteries and veins
- enclose a fluid filled cavity (subarachnoid space) which is needed for normal function/survival, yah know.
3 layers of meninges (most inner to outer)
pia, arachnoid, dura
what are arachnoid trabeculae?
what is in here
pillars of arachnoid tissue that extend to the pia, creating subarachnoid space
this holds CSF
define arachnoid villi & arachnoid granulations
villi = parts of the arachnoid matter that goes into the dural sinus
large villi = granulations
these are the major site for CSF reabsorption into the circulatory system
define subarachnoid cistern.
largest one?
other primary one?
large portion of subarchnoid space
cistern magna = largest one
lumbar cistern = place for lumbar puncture
potential epidural space vs. true epidural space
potential = exists between the dura & skull; dura is firmly attached to
ex: epidural space, subdural space & subarachnoid space
inside skull - it is not an actual space unless something goes wrong
true = dura is not attached to vertebrae - it is an actual space
function of the denticulate ligaments
lateral projects off the pia matter that anchor the spinal cord to the dura mater
define epidural space
area between the spinal dura & the periosteum lining of the vertebral canal
what is the falx cerebri
sickle-shaped vertical projection of dura that’s between the two cerebral hemispheres - attached to the crista galli
what is the tentorium cerebelli?
what passes through the tentorial notch?
horizontal projection of dura that forms a tent/roof for the posterior cranial fossa & cerebellum
the brainstem passes through
what is the diaphragmna sellae
what does the infundibulum connect?
small horizontal projection of dura that forms the roof for the pituitary fossa
it conects the pituitary with the hypothalamus
define herniation syndrome:
what cavities are important to consider?
it occurs when there is an intracranial event (bleed, etc) that causes an increase in intracranial pressure which forces the brain over the edge of the dura (how? idk.)
-supratentorial & infratentorial compartments are important
subfalcine herniation
= supratentorial herniation
cingulate gyrus & other structures herniate under the falx cerebri due to a unilateral mass lesion
uncal herniation
= supratentorial herniation
increase in intracranial pressure due to a hematoma; results in herniation of medial temporal lobe through tentorial notch
Clinical triad:
- blow pupil = compression of CN III
- Hemiplegia = compression of cerebral peduncles (descending corticospinal fibers)
- Coma = distortion of midbrain reticular formation – decreased consciousness
tonsillar herniation
infratentorial herniation
mass increases posterior cranial fossa presence forces the tonsil of the cerebellum to herniate into/through the foramen magnum
what causes an epidural hemorrage?
symptoms?
where does the blood go?
damage (fracture) of the bones on the lateral side of the skull
-usually rupture of the middle meiningeal A.
-initally no symptoms.. –> compressed brain tissue and possible death
the blood goes into this potential space between dura & skull
where does the blood enter the skull (through what structure)
foramen spinosum
what causes a subdural hematoma?
normal population?
where does the blood go?
located in the potential space – results from tearing of bridging vein – vulnerable to tearing as they cross the arachnoid space into the dural venous sinus
usually with the elderly - their brains are smaller which causes more availability for a shearing injury
where does the spinal cord end?
where does subarachnoid space end?
implications?
spinal cord ends between L1-L2
Subarachnoid space ends around S2
this means they can sample CSF without damaging the spinal cord below this L1-L2 spot — usually around L3-L4
what causes a subarachnoid bleed?
where does the blood go?
symptoms
bleeding into the subarachnoid space from a torn vessel such as a ruptured aneurysm
blood goes into the CSF-filled subarchnoid space = very painful
pain is due to meningeal irritation “worst headache of my life”
What causes intracerebral hemorrhage?
alternate name?
coup vs. counter coup
results from a vessel rupture in the brain; caused by a TBI / contusion
located within the brain substance
contusion on side of contact = coup
contusion on opposite of impact = counter coup
what can be a route for infection from outside to inside the cranial cavity
Emissary veins - they pass from outside cranial cavity to dural sinuses
diploic veins drain bones of the cavity & from emissary veins
4 major dural sinuses
- superior sagittal sinus - receives cerebral veins from cerebral hemispheres & diploic/emissary veins
- straight sinus = found within tentorium cerebelli; union of great cerebral vein & inferior sagittal sinus
- transverse sinuses = run horizontal
- R & L = sigmoid sinuses - become continuous with the intneral jugular vein
what does the straight sinus become
R & L transverse sinus
what passes through the cavernous sinus?
pair of sinuses on either side of the sella turcia
internal carotid artery & cranial nerves III, IV, V1, V2, & VI
what is cavernous sinus thrombosis?
cavernous sinuses have connections to the face where infection can spread from the face to the sinuses & cause clotting
that clotting = thrombosis
what is the internal carotid artery prone to?
aneurysm
what is meningitis
signs/symptoms
how to diagnose
inflammation of the meninges due to viral, bacterial, or fungal infection within the CSF
produces meningeal irritation = headache, lethargy, fever, vomiting, nuchal rigidity (stiff neck)
diagnose by sampling of the CSF via lumbar puncture
