Blood flow to brain (Exam 4) Flashcards
amount of blood volume needed by CNS?
50 mL/min of blood per every 100 g of tissue
25 mL/100 g of tissue puts cells in peril
8 ml/100g of tissue kills neurons in minutes
the BBB helps protect the brain against what?
internal pathogens and chemicals such as hormones
which artery in the brain does not come in pairs?
the basilar artery
where do internal carotid AA branch from?
the common carotids on each side of the neck
anterior cerebral artery supplies what?
medial cortex
some frontal and parietal cortex
internal capsule
BG
Middle cerebral aa supply what?
lateral cortex
what artery branches off the middle cerebral aa and supplies the caudate, putamen and ant. limb of internal capsule?
the lateral lenticulostriate A.
opthalmic A supplies what?
retina and dura
the anterior choroidal A supplies what?
int. capsule
thalamus
hippocampus
BG
anterior communicating A serves what purpose?
small conduit A between the ant. cerebral aa
posterior communicating A serves what purpose?
supplies hypothalamus
thalamus
hippocampus
what aa all join at the circle of willis?
anterior communicating
anterior cerebral
posterior communicating
posterior cerebral
where in the brain is a common place for an aneurism
circle of willis
this vascular structure surrounds the optic chiasm and pituitary glands and provides collateral circulation to provide redundancy to important structures in the brain in order to provide cont. blood flow in case one vessel is blocked
circle of willis
where does the basilar a arise from?
the junction of the two post. cerebral AA
what does the basilar a bifurcate into?
the vertebral AA
branches off basilar AA before it bifurcates
Posterior cerebral A
Superior Cerebellar A
Anterior Inferior Cerebellar A (AICA
pontine (paramedian) A
what does the posterior cerebral A supply?
most of midbrain
thalamus
temp. lobe
medial/inferior aspects of occ. lobe
what does the superior cerebellar A supply?
superior and middle cerebral peduncles
medial and lateral lemniscus
spinal trigeminal nucleus
spinothalamic tract
what does the pontine a supply?
pontine nuclei some CN nuclei corticopontine tract corticobulbar tract corticospinal tract (all these tracts are in the pontine area)
What does the AICA supply? (ant. inf. cerebellar A)
anterior undersurface of the cerebellum
branches of the Vertebral AA
anterior spinal A
posterior inferior cerebellar A (PICA)
Posterior spinal A
what does the anterior spinal A supply?
pyramids med. lemniscus of medulla med. long. fasciculus CN XII inferior olive
what does the posterior inferior cerebellar A supply (PICA)
Midbrain parts: >spinothalamic tract >spinocerebellar tract >CN V >nucleus ambiguous (i.e. parts of CN IX and X) Cerebellar parts: >vermis >inferior cerebellum
What does occlusion of the PICA lead to?
Wallenberg’s syndrome : disturbed speech, articulation and swallowing…
What does the posterior spinal artery supply?
fasciculus gracilis and cuneatus
spinal trigeminal nucleus
inferior cerebellar peduncle
some of Vagus Nerve- CN X
deficits from anterior cerebral A event
contralateral hemiplegia and sensory loss, mainly in LE
loss of motivation and exec. fxn
deficits from middle cerebral A event
contralateral hemiplegia and sensory loss in the UE and head aphasia sensory association deficits exec. fxn and working memory major multisystem dysfunction
deficits from a posterior cerebral A event
hemianopsia
syndromes related to midbrain regions:thalamus, subthalamic nuclei since they are fed by this A.
What is Weber’s syndrome?
*caused by Posterior Cerebral A event:
superior alternating hemiplegia:
ipsilateral occulomotor dysfxn (can’t abduct or have vert. gaze nc of CN III probs)
pupil dilation
contralateral hemiplegia( bc of probs with corticospinal and corticobulbar tracts)
deficits from a Superior cerebellar A. event
ipsilateral Horner’s Syndrome!
ipsilateral limb and gait ataxia
contralateral loss of pain and temp (spinothalamic)
what is Horner’s syndrome?
its an increase of the infulence of the parasympathetic drive to the eyeball–>prob that occurs with Superior Cerebellar A event:
ipsilateral pupil constriction
ptosis
sinking in of eyeball
deficits occuring with an anterior inferior cerebellar A event (AICA event)
ipsilateral loss of facial sensation (CN V)
ipsilateral horner’s syndrome
contralateral hemianesthesia
deficits occuring with Posterior inferior cerebellar A. Event (PICA EVENT)
Wallenberg’s syndrome:dysphagia, dysarthria
ipsilateral pain and temp of face probs (CN V)
contralateral pain and temp of body (spinothalamic)
vertigo (vest. nuclei)
ipsilateral horners syndrome
deficits from an anterior spinal A event (branch from vertebral A.)
medial medullary syndrome:
- contralateral conscious proprioception (med. lemniscus)
- paresis (UMNs in pyramidal tract)
- deviation of tongue to side of lesion (CN XII)
deficits from a posterior spinal A event (branch of Vert. AA)
ipsilateral conscious proprioception (nucleus cuneatus and gracillus)
a stroke in what A would give u Wallenberg’s syndrome?
PICA
a stroke in what AA would give u Horner’s syndrome?
PICA or superior cerebellar A.
a stroke in which A would give u Medial Medullary syndrome?
Anterior spinal A. (branch off vert. A)
What do symptoms of Vert. A compromise look like?
nystagmus, dizziness, nausea, blurred vision, loss of balance, falling
what is the window for administering tPA?
w/in 60 mins is best, but up to 4.5 hours
blood drains from the venous sinuses back to the heart via what veins?
the Jugular VV
why do the sinuses pose a risk of allowing infection into the CNS?
bc blood from the scalp drains into them too
what are the main sinuses?
superior sagittal sinus inferior sagittal sphenoparietal sinus cavernous transverse confluence
what does CSF do?
protects brain and carries away toxins and metabolites
how much CSF is in our system?
90-140 mL–>20-25 mL in the ventricles and the rest is in the subarachnoid space
how much CSF is produced each day and where is it produced?
70% produced in choroid plexus (up to 500 mL/day)
what is blocked in noncommunicating hydrocephalus?
cerebral aqueduct
describe communicating hydrocephalus
thickening of the achachnoid space from prior insult or infection with reduced absorption of CSF, if pressure increases the central spinal canal may enlarge
CSF flow
made in choroid plexus of lateral ventricles–>3rd ventricles( via interventricular foramina)–>4th ventricle (via cerebral aqueduct)–>subarachnoid space
