Blood Supply of Cortex-Wilson Flashcards
Blood supply to the medial brainstem
medial midbrain
medial medullary
Blood supply to the lateral brainstem
lateral midbrain
lateral medulla
What are the 3 arteries that supply the dorsolateral pons?
Caudal: AICA (pontomedullary junction)
Middle: circumferential (Short and long branches coming off of the basilar artery)
Rostral: Superior cerebellar
What does superior cerebellar artery supply?
structures as the junction between the pons and midbrain
What does AICA supply?
pontomedullary junction
What syndrome is the circumferential long and short arteries associated with?
long branches produce the lateral pontine syndrome
What tracts and nuclei are located at the dorsolateral part of the pons?
spinothalamic tract: descending hypothalamic fibers that provide control to the preganglionic sympathetic fibers in the spinal cord
spinal trigeminal tract: pain temperature coming from the face; extends all the way from spinal cord to the middle part of the pons
vestibular nuclei
motor nucleus of V
chief sensory of V
facial nucleus
What will occur if you damage the spinothalamic tract in the dorsolateral pons?
you will not only effects of the spinothalamic get Horner’s syndrome ipsilaterally
Lesions of what nucleus in the dorsolateral pons will result in paralysis of muscles of mastication?
motor nucleus of V
Lesion of the facial nucleus/nerve fiber in the dorsolateral pons will result in what symptoms?
flaccid paralysis of facial muscles in the upper and lower part of the face
What is the territory of long circumferential arteries?
- trigeminal spinal nucleus
- CN VII
- CN VI
Lateral pontine syndrome involves what cranial nerves/nuclei and tracts?
The motor nerves are very important to recognize their symptoms because they tell you where the stroke is.
- motor nucleus of CN V
- sensory nucleus of CN V (chief, spinal, proprioceptive)
- nucleus and fibers of CN VII
- vestibular nucleus (AICA)
- auditory nucleus (AICA)
- spinothalamic tract
- descending hypothalamic
- spinal trigeminal tract (and nucleus)
A lesion to the motor nucleus of V will lead to what symptoms?
You will get the motor nucleus of V leading to problems with muscles of mastication on one side; if you protrude the jaw, the jaw will deviate towards the lesioned side
A lesion to the sensory nucleus of V will lead to what symptoms?
chief sensory nucleus of V: fine touch, vibration
spinal trigeminal nucleus: is more caudal and extends from the cervical to the middle of the pons; lesion will result in ipsilateral loss of pain and temperature on the face
proprioceptive nucleus of V (mesencephalic nucleus of V): strange nucleus in that the cells are unipolar neurons; unsure of symptoms if lesioned
A lesion to the nucleus and fibers of CN VII will lead to what symptoms?
flaccid paralysis of muscles of facial expression whether there’s lesion in the nerves or nucleus
A lesion to the fibers of CN VIII will lead to what symptoms?
near the pontine medullary junction you have fibers of CN VIII; also the vestibular nuclei and auditory nuclei
when you have the monaural loss of hearing especially a major decrease to the sensitivity of hearing then you’re probably involving the cochlear nuclei????
although not a motor nucleus the involvement of the auditory pathways tells you that you’re at the pontomedullary junction and the artery obstructed is AICA
ipsilateral decrease in sensation (pain and temp) of the face
Where does the posterior cerebral artery go to?
occipital cortex particularly P2 where if lesioned there is loss of vision but with foveal sparing
What is an important landmark for the posterior cerebral arteries?
posterior communicating arteries that goes in between internal carotid and posterior cerebral arteries
What does P1 of posterior cerebral artery supply? What happens if it is lesioned?
supplies the midbrain and if it is unilateral you can get Weber’s syndrome getting the corticospinal tract and hemiataxia from the deep cerebellar fibers being affected (stroke involving the superior cerebellar peduncle or stroke involving the territory if the red nucleus)
the posterior comm is intact and you can still have blood coming from the internal carotid to the visual areas
What occurs with a lesion to P2 of posterior cerebral artery?
a decrease of blood flow to the visual cortex and a loss of vision
What occurs with a medial lesion of fibers coming off of basilar or P1 posterior cerebral artery?
you are hitting the corticospinal tract and red nucleus getting Weber’s syndrome
but you are sparing the medial lemniscus and spinothalamic tract
Where does the labyrinthine artery travel and what does it supply?
labyrinthine artery traverses the internal auditory meatus and supplies the inner ear in the petrous portion of the temporal bone
it may come off the basilar artery (it has a lot of variations)
The cerebral cortex is supplied by what 3 arteries?
- posterior cerebral artery: going more towards the occipital cortex (visual cortex= calcarine fissure) and also ventral surface of the temporal lobe
- internal carotid artery: gives off an anterior branch called anterior cerebral which supplies the frontal cortex running along corpus callosum
- middle cerebral: a continuation of ICA going to the lateral part of the brain (cerebral cortex) giving off some ventral and dorsal branches
If you have a thrombus that breaks free following a heart attack or if you’re palpating the internal carotid artery and the thrombus breaks free, this thrombus will do what?
go up and cause stroke of the either the entire middle cerebral artery or some of its branches
Where does anterior cerebral artery run and what does it supply?
runs along the corpus callosum to the medial aspect of the frontal lobes and parietal lobe
What are the two arteries that supply the medial aspect of the cerebral cortex?
posterior cerebral artery and anterior cerebral artery
What is located in between the central sulcus and the parieto-occipital sulcus?
parietal lobe!!
What is the major symptoms noted for the obstruction of the posterior cerebral artery?
-loss of vision with foveal sparing
the posterior cerebral artery runs to occipital cortex in the area of the visual cortex
What occurs with obstruction or stroke of the anterior cerebral artery?
runs to prefrontal cortex so executive functions are affected
runs to region that gives rise to the corticospinal tract going to the lower limb –> monoplegia of lower limb; some involvement of the proximal part of the upper limb; symptoms would be contralateral to the stroke
supply the motor areas providing upper motor neuron innervation to lower limb
Which arteries do cardiac embolism primarily form in the brain?
middle cerebral artery which is very unfortunate because they supply the important areas in terms of movement, speech, sensation, etc.
it is embedded in the lateral fissure
Middle cerebral artery as it goes over the lateral fissure gives off what penetrating branches that supply the area of the basal ganglia?
lenticulostriate arteries
Individuals with hypertension will have characteristic in their lenticulostriate arteries?
-the lenticulostriate arteries are small and have tendency to form aneurysm
-if there is rupture of these aneurysms you get focal lesions called
lacunar infarcts
How do lacunar infarcts result?
individual with HTN and because of the high blood pressure overtime this can cause weakening in the walls of the artery and the arteries start to balloon out and tilt until they actually rupture
the rupture produces a focal infarct where it ruptures called a lacunar infarct
Which Brodmann’s area will be affected by middle cerebral artery infarct?
area 4 and 6
primary and secondary motor and somatosensory cortex
On the left side of brain:
- Wernicke’s area: sensory aphasia
- broca’s aphasia: motor aphasia
What is the angular cortex? What syndrome and symptoms results if there is a stroke in this area?
follow the lateral fissure up on the LEFT side in most people
Gerstmann’s syndrome
- finger recognition difficulty
- alexia
- calculation difficulty
Stroke in the parietal cortex will result in?
- loss of spatial perception
- person will not recognize half of their world
What artery supplies your frontal eye fields (area 8)?
middle cerebral artery
What occurs with lesions to the frontal eye field?
the ability to look to the opposite side voluntarily is lost because the other cortex is dominating and the eyes is deviated towards the right way (where the stroke is located); eyes are looking in the opposite direction to where you have hemiplegia or monoplegia
In order to control eye movments
fibers descend and cross to the contralateral pons to the paramedian pontine reticular formation for horizontal gaze next to the abducens nucleus
What occurs with a lesion in the pons involving the paramedian pontine reticular formation?
the frontal eye field is intact but you still get a contralateral hemiparesis because you’re next to the corticospinal tract
but the paramedian pontine reticular formation on this side is receiving cortical input from the frontal eye field
eyes will deviate towards where the paralysis is (wrong way eyes)
Describe the circuit for voluntary horizontal parallel eye movement.
note the contralateral cortical control of the frontal eye fields ?????
embolism in middle cerebral artery
area of watershed will be spared because of collateral branches from anterior and posterior cerebral arteries ?????
extent of infarct is smaller than the area of the territory of the middle cerebral artery
watershed areas are often spared following obstruction of a single cerebral artery
?????Perfusion through these major arteries are less maybe due to low blood pressure, stroke, or heart attack plummeting your BP. What type of infarct does this cause?
infarcts in areas of overlap called the watershed infarct
watershed infarct may occur with severe drops in systemic blood pressure from shock or cardiac insufficiency
The ACA territory and ACA-MCA watershed???
lower limb and proximal part of the upper limb
Blood brain barrier
very important concept especially in pharmacy as drug administered to patient often times do not cross this barrier while some do
To cross the BBB, substances must be actively transported across the endothelial cells.
The BBB protects the brain from chemical fluctuations of blood that would disrupt synaptic transmission.
Trauma to the brain may disrupt the BBB resulting in vasogenic (excessive extracellular fluid) edema and cytotoxic edema (excessive intracellular fluid)
