Blood supply, Hemorrhage, Hydrocephalus Flashcards
Where are the lateral ventricles located?
Cerebral hemispheres
What connects the lateral ventricles to the 3rd ventricle?
Intraventricular foramen
Where is the 3rd ventricle located?
Between thalami
What connects the 3rd ventricle to the 4th ventricle?
Cerebral Aqueduct
Where is the 4th ventricle located?
Between cerebellum and pons
What drains the 4th ventricle?
Median and lateral apertures/foramina
What space does the CSF drain into?
Subarachnoid space
Arachnoid vili help to drain the CSF into what for reabsorption?
Dural venus sinus (superior sagittal sinus)
How much CSF is in the ventricles at a time?
20-25 mL
How much CSF is in the entire ventricular system at a time?
140 mL
Hydrocephaly
Excessive amount of CSF
In infants, the increased intracranial pressure caused by an increased amount of CSF causes what?
Enlargement of the head at the cranial sutures
In adults, the increased intracranial pressure caused by an increased amount of CSF causes what?
The sutures are fused thus the head cannot expand; Thus this will result in destruction of cortical matter or papilledema
External hydrocephalus
Excessive CSF in the subarachnoid space, compresses the brain to make more room
What are the 2 types of external hydrocephalus?
Supratentorial or intratentorial – or both
What is another name for Internal hydrocephalus?
Non-Communicating hydrocephalus
Internal hydrocephalus/non-communicating hydrocephalus
The CSF is NOT draining out of the ventricular system possibly due to an obstruction and so the ventricles enlarge!
Where do the ventricles enlarge due to internal hydrocephalus?
Proximal to the obstruction
Communicating hydrocephalus
CSF is getting out of the ventricular system but it not getting all the way back to the venous system for reabsorption
What is communicating hydrocephalus a mixture of?
Internal hydrocephalus and infratentorial external hydrocephalus
Where is the obstruction with communicating hydrocephalus?
In the subarachnoid space at the level of the tentorial notch prevents CSF from flowing from the infratentorial region up over the cerebral hemispheres in the supratentorial regions
What is the supratentorial external hydrocephalus most commonly associated with?
Atrophy of the cortex in a disease like Alzhemier’s
Where is the likely obstruction with internal hydrocephalus?
Intraventricular foramen (if lateral ventricles enlarged), cerebral aqueduct or median and lateral apertures
What makes CSF and how many of them are there?
Choroid plexus - each ventricle has one
What 2 arteries supply the majority of the blood to the brain?
Internal carotid and vertebral arteries
Occlusion of a large nutrient vessel to the brain
Focal ischemia - affects the area of the brain that artery supplies
What are the 2 mechanisms for a stroke and what does a stroke result in?
Ischemic and hemorrhagic
Stroke refers to acute focal neurological deficits from loss of blood supply to that area
With severe ischemia injuries what areas of the brain are most vulnerable?
Watershed regions
What are watershed regions in the brain?
Areas only supplied by the most distal branches of the cerebral arteries and are the first to be compromised
What area does the ACA supply?
2/3 of medial side and superolateral side of hemisphere
What can an occlusion in the ACA result in?
Contralateral sensation loss of LE
- ACA supplies posterior paracentral gyrus in the somatosensory cortex that correlates to the contralateral LE
What are the MCA branches?
Medial and lateral striate, central, frontal branches and angular arteries
What do the medial and lateral striate arteries supply?
Internal capsule, thalamus and corpus striatum
Where is the Central artery located?
In the central sulcus
What does the Central artery supply?
Primary motor and somatosensory cortices
postcentral gyrus
What does occlusion of the central artery result in?
Contralateral paralysis and paresthesia of the contralateral upper body, face, UE
What do the frontal branches supply?
Broca’s area
Occlusion of the frontal branches will result in?
Broca’s aphasia = Difficulty producing speech (motor)
What does the angular artery supply?
Wernicke’s area
Occlusion of the angular artery will result in?
Wernicke’s aphasia = Patients are talkative, but do not have much language comprehension - words lack content, meaning and choose inappropriate word choices
What supplies the central portion of the spinal cord?
Anterior spinal A.
What supplies the lateral medulla?
PICA - posterior inferior cereballar a.
What supplies the primary visual cortex?
Posterior cerebral A.
What can compress the posterior cerebral A. and result in vision changes?
Uncal herniation
What is the main superficial venous drainage of the cerebral hemispheres?
Superficial middle cerebral vein
What are the 2 veins that drain into the great vein of Galen?
Internal cerebral and Basal vein
Where does the Great vein of Galen drain into?
Straight sinus
A fracture of the pterion could rupture what and result in what?
Middle meningeal artery rupture could result in an epidural hematoma
As the epidural hematoma grows it compresses the nearby cerebral hemisphere. What can result?
Midline shift of the cerebral hemispheres = falx herniation (across falx cerebri)
Decreased venous drainage from retina from increased intracranial pressure
Papilledema
What swells with papilledema?
Optic disc
Bridging (cerebral) veins rupture
Subdural hematoma
What is likely ruptured with a subarachnoid hemorrhage?
Major blood vessels, as they all run through the subarachnoid space
Trauma to the midbrain may result in
Coma or state of consciousness
With a subarachnoid bleed, what are the symptoms?
ABRUPT and BURSTING headache, vomiting, neck rigidity, positive kernig’s sign
