Blood Supply To The Ventricles Flashcards
CSF has lower _____ than plasma.
CSF contains ___ similar to plasma.
Glucose and protein
Na, Cl, Mg
The ventricular system is lined by ____ and formed into vascular folds called _____, which produces the CSF. Where is this located?
Ependyma (glial cells)
Choroid plexus
Lateral ventricles, 4th ventricle
Choroid plexus makes CSF and releases it into the ____.
Lateral ventricle connects to 3rd ventricle by ____.
3rd ventricle connects the the 4th ventricle by _____.
4th ventricle is connected to the subarachnoid space by ____.
CSF will either go through arachnoid granulation into the ____ or down the ____ in the SC.
Lateral ventricle
Interventricular foramina of Monroe
Cerebral aqueduct
Lateral aperture (Foramen of Luschka) and median aperture (Foramen of Magendie)
Superior sagittal sinus; central canal
_____ is caused by an increase in cerebral mass/size due to excessive CSF.
Hydrocephalus
External or communicating hydrocephalus is caused by what?
What are the two types?
Excessive accumulation of CSF in the subarachnoid space; compresses CSF; outside the ventricles, which are normal size
Supratentorial external hydrocephalus: above the tentorium cerebelli; senile atrophy of the cortex (Alzheimer’s)
Infratentorial external hydrocephalus: below the tentorium cerebelli
What causes internal or noncommunicating hydrocephalus?
What obstructions can cause this?
Obstruction preventing the drainage of CSF produced in the ventricular system to the subarachnoid space
Causes dilation of the ventricles proximal to the obstruction
Interventricular foramen: 3rd ventricle choroid plexus ependymoma
Cerebral aqueduct: midbrain astrocytoma
Median and lateral aperatures: Arnold-chiari malformation of dandy-walker cyst
_____ is a combination of infratentorial external hydrocephalus and internal hydrocephalus.
What causes it?
Communicating hydrocephalus
Obstruction of the narrow space between the tentorial notch and midbrain -> caused by adhesions or fibrosis in subarachnoid space -> caused by previous inflammation (infantile meningitis), cerebral edema, uncial herniation
In communicating hydrocephalus, CSF can move through the ventricular system into the ____.
CSF cannot circulate over the cerebrum to be restored at the _____ near the superior sagittal sinus.
What does this cause?
Infratentorial subarachnoid space
Arachnoid villi
Hypertrophy of ventricles (internal hydrocephalus) and accumulation of CSF in the infratentorial space (external hydrocephalus)
What are clinical signs of hydrocephalus in infants and young children (less than 2 y/o)?
Adults?
Increase intracranial pressure is compensated by enlargement of cranial sutures
Increased intracranial pressure but sutures are fused so prevents head enlargement
Papilledema: CSF fills the subarachnoid space around the optic N causing bulging of optic disc
Abducens palsy: medially deviated eye
Ventriculomegaly: mental retardation
What veins drain the SC?
Where does it receive drainage from?
What does it empty into?
Where is it located?
Internal venous plexus of Batson
Receives drainage from veins in the SC
Empties into intervertebral veins -> segmental veins -> IVC
Located in the epidural space
*easy for cancer to metastasize
Deep drainage of the cerebral hemispheres: internal cerebral V
What does it receive from?
What does it drain into?
Location?
Receives thalamostriate V (drains corpus striatum) and anterior septal veins (draining limbic lobe)
Drains into the great vein of Galen
Runs next to the parahippocampal gyrus
Deep drainage of the cerebral hemispheres: basal V of rosenthal
What does it receive from?
What does it drain into?
Location?
Receives from middle deep cerebral (drains insula) and anterior cerebral V (drains frontal lobe)
Drains into great V of Galen
Runs next to the cerebral peduncle
Deep drainage of the cerebral hemispheres: great V of Galen
What does it receive from?
What does it drain into?
Location?
What does an occlusion cause?
Receives from internal cerebral V and basal V of rosenthal
Drains into the straight sinus -> confluence of sinuses
Runs next to the posterior portion of the corpus callosum
Fatality: because drains the deep cerebrum
Great V varix may compress the pineal body and the posterior commissure
The superior sagittal sinus usually empties directly into the ____.
Thrombosis causes what?
Straight sagittal sinus empties directly into the ____.
Thrombosis causes what?
R transverse sinus
Cortical ischemia and/or necrosis
L transverse sinus
Ischemia and/or necrosis of deep cerebrum; usually fatal
What four structures make up the blood brain barrier?
What is the fx?
What 3 locations do not have the BBB?
Endothelial cell layer
Basement membrane
Pericytes
Foot processes of astrocytes and oligodendrocytes
Barriers to passage of large molecules to and from the CNS
Pineal body, area postrema, median eminence of the hypothalamus
What two arteries pierce the dura mater?
Where do they run?
What arteries do they give off and where do these go/do?
Internal carotid A and vertebral A
Subarachnoid space
Cerebral A: supply blood to the brain; run in subarachnoid space -> branches penetrate the brain parenchyma while being surrounded by Virchow-Robin space (perivascular space) and pia mater
What four branches off the internal carotid A supply the anterior cerebrum?
Ophthalmic A
Anterior choroidal A
Anterior cerebral A
Middle cerebral A
What does the anterior choroidal A supply?
What is it prone to?
Choroid plexus of lateral ventricle, internal capsule, basal ganglia, thalamus, rostral midbrain
Thrombosis due to long course in subarachnoid space; can causes vascular insufficiency to globes pallidus and hippocampus in elderly
What does the anterior cerebral A supply?
Location?
What does an occlusion cause?
Anterior 2/3 of the medial side and supero-lateral portion of the hemisphere, paracentral lobule region, sensation and motor to the LE
Runs next to olfactory and optic N
Lack of blood to the paracentral lobule region of the cortex -> contralateral paresis and/or paraesthesia of leg and foot (motor front, sensory back)
What are four branches off the anterior cerebral A?
Recurrent A of heubner
Anterior communicating A
Anterior pericallosal A
Callosomarginal A
What is the water-shed area of the cortex?
Part of the cortex supplied by anterior and middle cerebral A.
If there is an occlusion in either artery, this area will undergo damage
What does the middle cerebral A supply?
Medial and lateral striate/thalamostriate, internal capsule, corpus striatum, and thalamus
What are the branches off the middle cerebral A?
What do they supply?
Central A: primary motor and somesthetic cortices
Frontal branches: premotor and prefrontal cortices; broca’s speech area
Parietal branches: association cortex
Temporal branches: primary auditory cortex
Angular A: supramarginal and angular regions; wernicke’s area
What do occlusions of the branches off the middle cerebral A cause?
Central A: contralateral spastic paralysis and/or paresthesia of the head and upper 1/2 of body
Frontal branches: broca’s aphasia (hear and comprehend but cannot appropriately respond= expressive language disorder
Parietal branches: interpretive disorders including body neglect, agnostic, and apraxia
Temporal branches: difficulty localizing sounds
Angular A: wernicke’s aphasia (fluent in speech but lacks content or meaning; inappropriate word choices= receptive language disorder
What arteries and branches supply the posterior cerebral cortex?
Vertebral A: anterior spinal A, posterior spinal A, posterior inferior cerebellar A
Basilar A: anterior inferior cerebellar A, labyrinthine A, superior cerebellar A, posterior cerebral A
What arteries supply the spinal cord?
Where are they located and what do they supply?
Where will a lesion to the SC interrupt blood flow?
Anterior spinal A: deep to anteromedian sulcus; supplies central gray matter and anteromedial portion of white matter
Posterior spinal A: branch off of vertebral A or PICA and run through posterolateral sulcus; supplies dorsal roots and posterior columns and peripheral margins of the cord
Where the SC is supplied by two arterial supplies: C2-3, T1-4, L1
Where is the great anterior A of Adamkiewicz?
What does it supply?
How can this artery get damaged?
Arises from the L inferior intercostal or superior lumbar A and contributes to the anterior spinal A
Inferior 2/3 of the spinal cord
Can become compromised secondary to thoracolumbar fx or surgical repair of AAA -> ischemic necrosis of SC
What causes central cord syndrome?
What are the S&S?
Disruption of blood flow to the anterior spinal A by:
Thrombosis, hyperextension injury of the neck, ischemia of central region of the SC
Abrupt onset, central necrosis and cavitation of the SC, sensory AND motor deficits to UE>LE, distal musculature > proximal musculature
What does the posterior inferior cerebellar A supply?
What does an occlusion of the artery cause?
Posterior inferior portion of cerebellum, posterolateral aspect of the medulla, choroid plexus of the 4th ventricle
Lateral medullary syndrome/Wallenberg syndrome
What does the anterior inferior cerebellar A supply?
Where is it located?
What CN is it by?
Anterior inferior portion of the cerebellum, superior and middle cerebellar peduncles, part of brainstem
Pontobulbar sulcus
CN VI, VII, VIII, flocculus of the cerebellum
What does the superior cerebellar A supply?
Located?
Superior lateral portion of cerebellum, deep cerebellar nuclei, part of pons and midbrain
Posterior to CN III
Where does the labyrinthine A come from?
What does it supply?
What does labyrinthinitis cause?
Branch of basilar A or off AICA
Main artery to the internal ear
Atherosclerosis or inflammation of the labyrinthine A resulting in irritation of the vestibulo-cochlear apparatus -> disturbs equilibrium and/or hearing
What do the pontine branches supply?
Medial and lateral aspects of the pons
Distribute to regions of the brainstem in a “pie wedge” pattern -> sometimes seen with necrosis from a brainstem lesion
What are branches off the posterior cerebral A?
What do they supply?
Penetrating branches: internal capsule, thalamus, choroid plexus of the lateral ventricle, upper midbrain
Temporal branches: inferior temporal cortex
Parietooccipital A: visual association cortex
Calcarine A: primary visual cortex
Posterior pericallosal A: anastomoses with the anterior pericallosal A of the anterior cerebral
What causes an occlusion to the PCA?
What does this occlusion cause?
Thrombosis, compression due to uncal herniation
Ischemic necrosis of the primary visual cortex; contralateral homonymous hemianopsia with macular sparing
What causes a falx herniation?
Symptoms?
If a unilateral space-occupying lesion is present -> the cingulate gyrus can herniate and push beneath the free edge of the falx cerebri
HA, contralateral leg weakness, no deficits
What causes a uncal herniation?
What are the S&S?
What happens if the midbrain becomes involved?
If a unilateral space-occupying lesion is present -> the uncus can herniate and push though the tentorial notch
Compresses PCA and CN III: unilateral dilating pupil, CN III compression (oculomotor N palsy)
Contralateral hemiparesis and respiratory compromise; kernohan’s notch
Kernohan’s Notch:
Uncal herniation causes pressure on the ____, causing _____.
The increased pressure pushes the brainstem into the _____, causing _____.
Ipsilateral brainstem
Contralateral limb weakness
Tentorium cerebelli
Ipsilateral limb weakness giving a false localizing sign
What is a tonsilar herniation?
Cerebellar tonsils herniate through the foramen magnum and compress the medulla -> respiratory arrest
Acute and rapidly fatal
What is an epidural hematoma?
Cause?
What are the S&S?
If not treated, what will it cause?
High pressure bleed expands the epidural space, separating the dura mater from the bone and creating a blood filled space
Fracture at the pterion ruptures the middle meningeal A running between the dura mater and the skull
Trauma -> initially unconscious -> rapid recovery -> few hours pass -> neurological symptoms…lens shape on MRI
Hematoma will press on the cerebral hemisphere and can lead to herniations (uncal herniation compress midbrain and decrease consciousness)
What is a subdural hematoma?
Cause?
S&S?
What is the difference in causes between a child and an elderly patient?
Ruptured veins cause blood to accumulate in the subdural space
Head trauma causes cerebral veins to rupture as they cross the subdural space
Crosses suture lines on MRI; delayed symptoms due to slower pooling of blood, more acute onset, lethargy, seizures, HA
Children= skull fx Elderly= fragile blood vessels
What causes a subarachnoid hemorrhage?
Why?
How can test/know?
Rupture of a blood vessel in the subarachnoid space
Subarachnoid space contains all major blood vessels supplying the CNS
Presence of erythrocytes in the CSF
Sample CSF through lumbar puncture at L4-L5 (SC ends L2)
