4 - Circulation to the Brain and Spinal Cord: CSF and Vascular Systems Flashcards
CSF is formed in ____ (more specifically ___ ___) and flows between ventricles and into ____ space
ventricles, choroid plexus
subarachnoid space
2 functions of the CSF?
- supplying nutrients and removing waste products - it is then absorbed into venous system
- along with meninges, provides shock absorption to brain when head is hit
What is the lateral wall of the lateral ventricles?
caudate nucleus - with tail of caudate superior to inferior horn of lateral ventricle
What is below body of lateral ventricle? above?
below: thalamus
above: corpus callosum
what connects the lateral ventricles to each other and to 3rd ventricle?
interventricular foramina/foramina of Monro
The 3rd ventricle is narrow in midline of what?
diencephalon
what is the 3rd ventricle surrounded by?
thalamus and hypothalamus
what connects 3rd and 4th ventricles thru midbrain?
cerebral aqueduct/aqueduct of sylvius
4th ventricle is posterior to what? anterior to?
posterior to pons/medulla
anterior to cerebellum
what does the 4th ventricle connect to? (inferior of it)
central canal of spinal cord
what does the 4th ventricle drain into? through what?
drains into subarachnoid space through 2 lateral foramina (foramina of luschka) and midline foramen of Magendie
__ mater: outer layer firmly attached to inside of skull and inner layer attached to arachnoid
dura
dura mater: inner and out layers fused except where?
dural sinuses which collect CSF and venous blood
2 dense projections of inner layer of dura? locations?
- falx cerebri (sagittal)
- tentorium cerebelli (frontal)
Unique interaction between dura and arachnoid mater?
arachnoid mater has villi/granulation that go thru dura into venous sinuses to allow CSF flow into them
pia mater is connected to arachnoid through ___ ___ (collagen fibers) to allow suspension of brain in CSF?
arachnoid trabeculae
To make CSF, blood is filtered and transported thru which 3 layers?
web of (1) capillaries embedded in (2) connective tissue and (3) epithelial cells
- creates a protein rich substance like plasma
Most often cause of epidural hematoma?
fx of parietal or temporal bones tearing middle meningeal artery
is an epidural hematoma usually a quick or slow accumulation of blood?
quick
is a subdural hematoma usually a quick or slow accumulation of blood?
slow
which hematoma is characterized with a period of lucidity then quick deterioration?
epidural
which hematoma is characterized by its “lens” shape?
epidural
what is a subdural hematoma most often due to?
venous bleed
what hematoma is characterized by a long broad crescent moon shape?
subdural
is hydrocephalus congenital, acquired or either?
can be either
Triad of symptoms of hydrocephalus?
worsening gait, incontinence, HA or cognitive deficits
___ hydrocephalus occurs when the ventricular system is intact with blockage caudal to 4th ventricle
communicating
____/____ hydrocephalus occurs when the blockage is within the ventricular system (usually cerebral aqueduct)
noncommunicating/obstructive
what makes pain worse with meningitis?
upright position, head movement, sneezing or coughing
which homunculus is on the post central gyrus?
sensory
which homunculus is on the pre central gyrus?
motor
about how much of the spinal cord does the anterior spinal artery supply?
2/3
what is it called when arteries connect to abnormal
vessels rather than capillaries to
veins?
arteriovenous malformation (AVM)
- congenital
- can be asymptomatic until rupture
- can be found anywhere in the brain
what is a thin walled outpouching
from artery or vein?
aneurysm
Can be congenital and
worsen with age, HTN
► Or can develop with time
► Can be asymptomatic until
it leaks or ruptures
► Can be found anywhere in
circulatory system
what is the specialized barrier between
capillary endothelium of CNS and extracellular space?
blood brain barrier
Blood brain barrier is absent in areas that __ the blood or ____ into
the blood.
sample, secrete
where in the brain is the blood brain barrier absent?
Parts of hypothalamus and other areas close to 3rd/4th
ventricles
- Special ependymal cells separate “leaky” regions from
barriered ones (like a barrier between the barrier and non-barrier regions)
O2 use ____ (inc/dec) from brainstem to cerebral cortices
increases
- Cortex more vulnerable to O2 loss than life centers of brainstem
- May explain why some people can live in persistent vegetative state for long time
Cerebral arteries autoregulate local blood flow dependent on blood
pressure and metabolism. What would cause arteries to dilate?
- low BP
- low O2
- low pH
- high CO2
- high lactic acid
Cerebral arteries autoregulate local blood flow dependent on blood
pressure and metabolism. What would cause arteries to constrict?
- high BP
- high O2
- high pH
- low CO2
- low lactic acid
Excessive fluid in brain tissue is known as what?
cerebral edema
3 potential causes of cerebral edema?
- TBI, including concussion
- heart attack
- high altitude cerebral edema (HACE)
Cerebral edemas are often progressive because fluid pressure causes ___ then causing
arterioles to dilate which increases ____ ____ and permeability
and more edema
ischemia, capillary pressure
- fluid pressure > ischemia
- ischemia > arterioles to dilate
- arterioles dilate > increased capillary pressure and permeability
- increased capillary pressure and permeability > more edema
Intracranial pressure is monitored by a monitor placed where?
lateral ventricle
Normal intracranial pressure?
5-15 mmHg
Intracranial pressure above __ is abnormal and __ or greater is pathologic and contraindication
to PT.
15, 20
What can excessive ICP do?
- move brain structures
- compress brain tissue
- cause brain herniation
- cause hydrocephalus
- disrupt blood supply
4 types of brain herniation?
- cingulate
- uncal
- central
- tonsillar
what type of brain herniation causes pressure on the falx cerebri and can cause issues with the lower limbs?
cingulate
what type of brain herniation has pressure against the midbrain causes CN 3 dysfunction and LOC (reticular activating system)?
uncal
what type of brain herniation has pressure against diencephalon moving it, midbrain and pons down?
central
what type of brain herniation stretches basilar artery with brainstem ischemia/edema and causes B paralysis and impaired consciousness and oculomotor
function?
central
what type of brain herniation has pressure of cerebellar tonsils on brainstem impair consciousness and 4th ventricle?
tonsillar
Venous system: spinal cord and medulla drain into small veins into ___ veins into ____ ___ ___
radicular, epidural venous plexus
Venous system: cerebral veins drain into dural sinuses into ___ ___ vein
internal jugular
Venous system: superficial veins drain cortex and neighboring white matter into ___ ___ __ or sinus at inferior cerebrum
superior sagittal sinus
Venous system: deep cerebral veins drain basal ganglia, diencephalon, adjacent white matter into ___ ___
straight sinus
Venous system: superior sagittal and straight sinuses meet at ___ ___ __
confluence of sinuses
Venous system: the ___ ___ arise from the confluence and drain into internal jugular vein
transverse sinuses
___ ___ ___:
- brief localized loss of brain function
- resolves within 24 hours
- medical emergency due to high likelihood of bigger stroke to happen late (so it is a type of stroke)
transient ischemic attack
2 types of stroke?
infarction, hemorrhage
Stroke: infarction: embolus
- where is the clot from?
- timeline for loss of function?
Embolus:
- clot from somewhere else
- sudden, quick loss of function
Stroke: infarction: thrombus
- where is the clot from?
- timeline for loss of function?
thrombus:
- narrowing and/or clot in area involved
- gradual worsening of function (mins to days)
___% of all strokes are infarcts
80
what artery to most strokes affect?
middle cerebral artery
Stroke: slow occlusion of artery (years) can allow system to develop ____
compensations
Stroke: small deep circulation infarcts are called what?
lacunar infarcts
- most common in basal ganglia, internal capsule, brainstem and one other place that i dont know
Hemorrhage stroke: slow leak or explosive rupture?
can be either
- rupture will cause sudden LOfunction, severe HA, to loss of consciousness
Damage from a hemorrhage stroke is due to?
- downstream loss of blood to brain areas
- pressure of extracellular blood accumulating
- blood where it is not supposed to be is irritant to brain tissue
STROKE: VERTEBRAL ARTERIES:
- prone to what injuries?
- symptoms?
- prone to shear force injuries, esp abrupt cervical rotation or hyperextension with chief symptom of pain
- symptoms:
1. gait/limb ataxia/incoordination and weakness
2. oculomotor and oropharyngeal impairments
3. numbness
4. dizziness
5. HA
6. vomiting
STROKE: BASILAR ARTERIES
- what does complete blockage cause?
- what does partial blockage cause?
- complete blockage causes death due to ischemia of brainstem with vital functions
- partial blockage can cause:
1. tetraplegia
2. numbness
3. LOC
4. cranial nerve damage
example would be locked in syndrome
STROKE: ANTERIOR CEREBRAL ARTERY
- what are the symptoms?
- hemiparesis/hemisensory loss to contralateral side (based on homunculus think lower limbs)
- personality changes (like flat affect and impulsivity, gait apraxia)
STROKE: MIDDLE CEREBRAL ARTERY
- symptoms?
- based on each side?
- hemiparesis/hemisensory loss to contralateral side (based on homunuculus think face and upper limb)
- L side: language
- R side: spatial relationships, neglect, nonverbal communication
STROKE: POSTERIOR CEREBRAL ARTERY
- supplies what?
- symptoms?
- supplies midbrain, diencephalon, hippocampus (declaritive memory), thalamus (pain, contralateral hemiparesis/hemisensory loss)
- eye movements
- cortical blindness
STROKE: ____ ___
- anastomoses of distal branches of cerebral arteries
- vulnerable to ischemia
watershed areas
