Lecture 22- Cerebral Vascular and Cerebrospinal Fluid Flashcards
T or F: Cerebral blood flow is locally regulated to ensure constant blood flow
T
In what 2 ways can metabolites influence blood flow
- Hypoxia/Hypercarbia -> Vasodilation and increased blood flow
- Hypocarbia -> vasoconstriction and decreased blood flow
How can you reduce intracranial pressure that occurs from a brain bleed, stroke, tumor, aneurysm or high blood pressure
Hyperventilation to decrease carbon dioxide and reduce blood flow and intracranial pressure
What is the blood brain barrier
Barrier between vascular system and brain to prevent substances from entering cerebral space
How do substances pass the blood brain barrier
Depends on molecular size, lipid miscibility and degree of ionic dissociation to go through tight junctions
What 3 diseases result from leaky blood brain barrier
- Epilepsy
- Alzheimer’s disease
- MS
What are the 2 starting points for cerebral blood supply and their respective arteries
- Anterior blood supply -> carotid artery
- Posterior Blood Supply -> Vertebral artery
The anterior blood supply is made up of what 2 carotid arteries
- Right Common Carotid Artery
- Left Common Carotid Artery
Where does the right common carotid artery branch from
Brachiocephalic trunk
Where does the left common carotid artery branch from
Highest part of the aortic arch
2 roles of carotid body and sinus at branches of carotid artery
- Blood pressure and respiration
- Carotid pulse
Label the missing parts of the diagram of the anterior blood supply system
Function of the anterior communcating artery
Joins the two cerebral arteries and supplies part of corpus collosum that is an important blood source for 2 cerebral hemispheres
T or F: The anterior communicating artery is a frequent site for aneurysm formation
T
Function of the anterior cerebral artery
Supplies inferior and medial surface of frontal and parietal lobes
What would occur if there was a blockage of the anterior cerebral artery?
It would damage lower extremities as they are represented more medially in homunculus of brain
Function of the middle cerebral artery
Supplies lateral surface of frontal, parietal and temporal lobes
What 3 possibilities can occur if the middle cerebral artery is affected by a stroke
- Sensorimotor deficits in contralateral face and limbs
- Global Aphasia (dominant hemisphere) effecting language, auditory and visual comprehension
- Neglect Syndrome (nondominant hemisphere) causing individual to not recognize contralateral side of body
Label the diagram of the missing parts of the posterior blood supply system
Function of the posterior inferior cerebellar artery (PICA)
Supplies a large part of the cerebellum
What disease occurs and symptoms from a stroke of PICA
Wallenberg syndrome: ipsilateral loss of pain/temp of face, contralateral loss of pain/temp of neck, limbs and trunk, ipsilateral Horner syndrome (dropping of eyelid and constricted pupil), hoarseness, double vision, ipsilateral loss of taste, ipsilateral cerebellar ataxia
What are the 3 sources of blood supply in the spinal cord
- Single anterior spinal artery
- Paired posterior spinal arteries
- Radicular and segmental branches
What are the 3 key arteries from the posterior blood supply system of vertebral artery
- Anterior inferior cerebellar artery
- Pontine arteries
- Superior cerebellar arteries
Function of superior cerebellar artery
Supplies dorsal surface of cerebellum and midbrain
Function of pontine arteries
Supplies pons
Function of anterior inferior cerebellar artery
Supplies cerebellum and pons
Function of posterior cerebral artery
Supplies medial/interior surface of temporal and occipital lobe, small strip of lateral occipital lobe, and calcarine artery (supplies primary visual area)
What happens if there is a stroke at the posterior cerebral artery
Contralateral homonymous hemianopsia (entire visual field of opposite side affected) and if damage occurs to dominant hemisphere-> reading and writing are impaired
Label the missing parts of the circle of willis
Function of the circle of Willis
Insurance policy so acts like cascular shunt to allow collateral circulation to brain should something become occluded
Label which of the colored parts are more medial or lateral
Label which of the colored parts are more medial or lateral
Give a diagnosis and treatment to this case
Diagnosis: Hypoperfusion to left middle cerebral artery
Treatment: Mechanical thrombectomy with stent retriever performed to return blood flow
what is a difference between systemic and cerebral veins?
cerebral veins are without valves or muscle tissue to assist and regulate flow
sinuses of the brain empty into the :
internal jugular vein
what are the 3 venous drainage sinuses of the brain?
- Inferior sagittal sinus
- Superior sagittal sinus
- Transverse sinus
all 3 sinuses of the brain drain into the ______ sinus
sigmoid
what is cerebral venous sinus thrombosis? and causes/riskfactors
Blood clot forms in sinuses which Prevents blood from draining out – results in hemorrhage
- Caused by bacterial infections or malignancy
- Pregnancy and oral contraceptives are risk factors
where are the sinuses located?
between the periosteal and meningeal layer of the dura mater
what is the falx cerebri?
a dural fold that separates the right and left hemispheres
what is the main role of dural folds
Provide support to the brain and dural venous sinuses
what are the 3 dural folds in the human brain and where are they located?
- Falx Cerebri – vertical, between two cerebral hemispheres
- Tentorium Cerebelli – horizontal, between cerebral hemispheres and cerebellum
- Falx Cerebelli – vertical, between cerebellar hemispheres
T or F: the subarachnoid space contains the CSF, cerebral arteries and veins
true
what are the 3 types of hemorrhage found in the brain? and which vasculature is usually involved in each?
- subarachnoid - cerebral arteries
- subdural - cerebral veins
- epidural - meningeal vessels running on the surface of the cranium
3 functions of cerebrospinal fluid:
- Acts as a cushion for the brain
- Vehicle to remove metabolic waste
- Maintains stable ionic environment
where is CSF produced?
by cells in the choroid plexus located in the lateral, third and fourth ventricles
how much CSF does the choroid plexus produce in a day?
500mL (volume is 150mL but is replenished 3-4x per day to remove waste)
describe the flow/pathway of CSF
Lateral ventricles → interventricular foramen → third ventricle → cerebral aqueduct → fourth ventricle → median/lateral aperture → subarachnoid space around brain and spinal
cord → absorbed into dural veinous sinuses
what is hydrocephalus?
Obstruction of the CSF pathway causes stagnation of flow which Results in dilation of parts of the ventricular system due to abnormal collection of CSF
what is the difference between obstructive and communicating hydrocephalus?
obstructive = within the ventricles, communicating = outside ventricles in subarachnoid space.
what is the treatment for hydrocephalus?
A shunt (catheter that allows CSF to flow) can be inserted into the ventricle - end of the shunt can be secured in the peritoneal cavity or into the atrium of the heart
