circulation to the brain and spinal cord: CSF and Vascular Systems Flashcards
what are the two fluid systems?
cerebrospinal fluid (CSF)
vascular
what are examples of CSF? (3)
ventricles
meninges
CSF
what are examples of vascular?
arterial supply
veins and venous sinuses
regulatory mechanisms of blood supply
Where is CSF formed? and where does it flow?
ventricles (choroid plexus)
between ventricles and into subarachnoid space then eventually is absorbed into venous system
what is the CSF responsible for?
supplying nutrients and removing waste products
2 C shaped lateral ventricles borders:
lateral – (?)
below body – (?)
above body – (?)
lateral –> caudate nucleus with tail of caudate superior to inferior horn
below body –> thalamus
above body –> corpus callosum
what do the 2 C shaped lateral ventricles connect to?
connect to each other and to the 3rd ventricle by inter-ventricular foramina (foramina of Monro)
what is the third ventricle surrounded by?
thalamus and hypothalamus
what connects the 3rd and 4th ventricles?
cerebral aqueduct thru midbrain
where is the 4th ventricle?
posterior to pons/medulla and anterior to cerebellum
what does the 4th ventricle connect to?
the central canal of the spinal cord
where does the 4th ventricle drain?
subarachnoid space thru 2 lateral foramina (foramina of Luschka) and midline foreman of Magendie
what secretes CSF?
choroid plexuses
what are epidural hematomas most often a result of?
fracture of the parietal or temporal bones tearing middle meningeal artery
what are three key characteristics of epidural hematoma?
quick accumulation of blood
period of lucidity, then quick deterioration
characteristic lens shaped accumulation of blood
what is a subdural hematoma most often a result of?
venous bleed
what is one key characteristic of a subdural hematoma?
slow progressive deterioration (days, months)
congenital or acquired hydrocephalus:
what is a characteristic of infants with non-fused skulls?
enlarged heads and other symtpoms/signs
congenital or acquired hydrocephalus:
what is a characteristic of children/adults with fused skulls?
excessive pressure especially of white matter and will exhibit a TRIAD of symptoms
what is the triad of symptoms for congenital or acquired hydrocephalus?
worsening gait, incontinence, HA or cognitive deficits
what is communicating hydrocephalus?
ventricular system intact with blockage caudal to 4th ventricle
what is noncommunicating/obstructive hydrocephalus?
blockage within ventricular system (usually cerebral aqueduct)
what are the four types of hydrocephalus?
congenital or acquired
communicating
noncommunicating/obstructive
requires ventriculoperitoneal stunt
what is meningitis?
inflammation of the meninges
when does pain increase for meningitis?
with upright position, with head movement, and sneezing or coughing
how many arteries are supplying anterior SC?
one artery
how many arteries are supplying for posterior SC?
two arteries
how much of the spinal cord does the anterior spinal artery supply?
1/2 of SC
what is arteriovenous malformation?
arteries connect to abnormal vessels rather than capillaries to veins
true or false: arteriovenous malformations are congenital
true
what are three characteristics of arteriovenous malformation?
can be asymptomatic till ruptures
symptoms can include local pain
can be found anywhere in body
what are aneurysms?
thin walled out-pouching from artery or vein
true or false:
aneurysms can be congenital and worsen with age (hypertension)
TRUE
what is one main characteristic of aneurysms?
can be asymptomatic until it leaks or ruptures
can be found anywhere in circulatory system
what is the blood brain barrier?
a specialized barrier between capillary endothelium of CNS and extracellular space
what is a characteristic of permeability for the blood brain barrier? and why is it important?
permeability is less than regular capillaries so large molecules can’t enter
it is important because it is beneficial to prevent lots of pathogens from entering CNS and prevents certain drugs and protein antibodies from entering
where is the blood brain barrier absent in?
areas that sample the blood or secrete into the blood such as…
parts of hypothalamus and other areas close to 3rd/4th ventricles AND special ependymal cells separate leaky regions from barrier-ed ones
what is more vulnerable to O2 loss than life centers of brainstem?
cortex
when does dilation of the cerebral arteries occur?
if BP, O2, or pH levels are low OR CO2 or lactic acid is high
when does constriction of the cerebral arteries occur?
if BP, O2, or pH levels are high
or
if CO2 or lactic acid is high
what is cerebral edema?
excessive fluid in brain tissue
what are common causes of cerebral edema?
TBI, including concussion
heart attack
high altitude cerebral edema
cerebral edema is progressive because fluid pressure causes ischemia which leads to what?
arterioles to dilate and increases capillary pressure and permeability and more edema
what is intracranial pressure?
pressure within the skull, measured by monitor in lateral ventricle
what is the normal range of intracranial pressure?
5-15 mm HG
what does an intracranial pressure above 15 mean?
abnormality
what does an intracranial pressure above 20 or greater mean?
pathologic and contraindication for PT
what can an excessive ICP cause?
compress brain tissue
move brain structures
cause hydrocephalus
cause brain herniation
disrupt blood supply
brain herniation:
pressure against the falx cerebri (cingulate) can likely cause what? (homunculus)
it can lead to compression in the region of the homunculus primarily controlling the lower limb particularly the foot and leg
brain herniation:
pressure against the uncal on the midbrain can cause what?
CN3 dysfunction and loss of consciousness (reticular activating system)
brain herniation:
pressure against the central aspect of the brain against the diencephalon moving it, midbrain and pons down causes what?
stretches basilar artery with brainstem ischemia/edema
B paralysis and impaired consciousness and oculomotor function
pressure on the cerebellar tonsils putting downward on brainstem does what?
impairs consciousness and and can lead to respiratory and cardiovascular failure
what is a transient ischemic attack?
brief localized loss of brain function
resolves within 24 hours
medical emergency due to high likelihood of bigger stroke to happen alter
what is a stroke?
CVA lasting longer than 1 day
“brain attack”
what are two types of infarctions?
embolus and thrombus
what is an embolus? and what can it cause?
clot from somewhere else
sudden quick loss of function
what is a thrombus? and what can it cause?
narrowing and/or clot in area involved
gradual worsening of function (mins to days)
what is the main difference between embolus and thrombus?
embolus is SUDDEN and QUICK loss of function
thrombus is GRADUAL worsening of function
80% of all strokes are what type?
infarctions
most strokes affect what blood vessels?
middle cerebral artery
what are small deep circulation infarcts called?
lacunar infarcts
what is a hemorrhage?
rupture of vessel
what can a hemorrhage cause?
sudden loss of function, severe HA (headache) to loss of consciousness
what is the damage from a hemorrhage due to?
downstream loss of blood to brain areas
pressure of extracellular blood accumulating
blood where not supposed to be is irritant to brain tissue
stroke signs/symptoms by arterial location:
what injuries are vertebral arteries prone to?
shear force injuries, especially abrupt cervical rotation or hyperextension with chief symptom of pain
the vertebral arteries supply the cerebellum and brainstem…
so what happens when there is a disruption of blood flow (vertebrobasilar ischemia) in the vertebrobasilar system?
gait/limb ataxia/incoordination and weakness, oculomotor and oropharyngeal impairments, numbness, dizziness, HA, vomiting
what does complete blockage of the basilar artery cause?
death due to ischemia of brainstem with vital functions
what can partial blockage of the basilar artery cause?
tetraplegia, numbness, loss of consciousness, cranial nerve damage
a partial blockage of what artery can cause locked in syndrome?
basilar artery
a stroke in the anterior cerebral artery can cause hemiparesis/hemisensory loss to what body parts more than others?
the contralateral lower limb more than the upper limb or face
what can a stroke in the anterior cerebral artery cause?
hemiparesis/hemisensory loss to contralateral lower limb and personality changes
what is the mnemonic for MCA strokes to know what part of the body is affected?
MCA
Mostly Cheek and Arm
what body parts result to hemiparesis/hemisensory loss to contralateral side during a stroke of the MCA?
the upper limbs and face
if there is a stroke on the left side of the brain in a MCA stroke, what is affected?
language
if there is a stroke on the right side of the brain in a MCA stroke, what is affected?
spatial relationships
neglect
nonverbal communication
what parts of the brain does the posterior cerebral artery supply?
midbrain, diencephalon, hippocampus, and thalamus
if the PCA stroke affects the hippocampus, what is affected?
declarative memory
if the PCA stroke affects the thalamus, what is affected?
pain, contralateral hemiparesis/hemisensory loss
if there is a PCA stroke, what is affected?
blood supply to the midbrain, diencephalon, hippocampus, thalamus, eye movement, and cortical blindness
what are watershed areas in terms of a stroke?
regions of the brain that lie at junctions between two major cerebral arteries
what is arterial anastromoses?
occurs when two or more arteries joint to form a network, providing collateral circulation to tissues in case on artery becomes blocked
are watershed areas vulnerable to ischemia?
yes
