CNS Blood Supply Flashcards
vessels involved in the circle of willis
-ICA
-ACA
-Acom
-Pcom
-PCA
-basilar artery
carotid syphon
tortuous portion of the ICA with high risk for calcification and aneurysm
terminal branches of the internal carotid artery (ICA)
1) anterior cerebral arteries (ACA)
2) middle cerebral arteries (MCA)
intermediate branches of the internal carotid artery (ICA)
1) ophthalmic artery
2) posterior communicating artery (Pcom)
3) anterior choroidal artery
ACA branches & their perfusion
1) superficial branches to:
-paracentral lobule, where hip, lower limb, and genital area are represented
-frontal lobe cognitive area
-cingulate gyrus and corpus callosum
2) perforating branches to:
-deep cerebral nuclei
-internal capsule
A1-A4 of the anterior cerebral artery (ACA)
*A1 is pre-communicating (before the anterior communicating artery)
*A2, A3, and A4 are post-communicating
signs of an ACA stroke
contralateral paralysis and sensory loss - lower limb, urinary incontinence:
*weakness of contralateral LEG
*sensory loss of contralateral LEG
*urinary incontinence
*altered mental status or judgement
*behavioral and emotional disorders
A1 vs A2 occlusion of ACA
*in A1 occlusion, there is distal ACA circulation via Acom
*in A2 occlusion, there is NO distal perfusion of tissue
segments of the MCA
1) M1 = deep/horizontal
2) M2 = lateral (sylvian) fissure
3) M3/M4 = cortical (superior and inferior divisions)
MCA perfusion and branches
1) superficial branches to:
-lateral surfaces of frontal, parietal, and temporal lobes
-cortex in sylvian sulcus, including insula
-portion of occipital lobe
2) deep perforating branches
important functional areas supplied by the MCA
*primary and secondary motor
*primary and secondary somatosensory
*parietal association cortex
*Wernicke’s area and Broca’s area
*primary and secondary auditory
signs of an MCA stroke
contralateral paralysis and sensory loss - lower face & upper limb; aphasia (if dominant hemisphere) OR hemineglect (if nondominant hemisphere):
*contralateral weakness of UPPER LIMB AND FACE
*expressive (non-fluent) aphasia (Broca’s)
*contralateral sensory loss of UPPER LIMB AND FACE
*receptive (fluent) aphasia (Wernicke’s)
*gaze preference to ipsilateral side
*neglect: non-dominant hemisphere
*possible partial visual deficits due to white matter involvement
lenticulostriate arteries
*arteries that supply regions of the BASAL NUCLEI
*lesions found in striatum / internal capsule
medial lenticulostriate arteries supply?
supply the globus pallidus, the medial portion of the putamen, and the anterior internal capsule
medial lenticulostriate artery - alternative name
Recurrent Artery of Heubner
medial lenticulostriate arteries arise from?
arise from the A1 segment of the ACA (anterior cerebral artery)
lateral lenticulostriate arteries arise from?
arise from the proximal MCA (usually M1)
lateral lenticulostriate arteries supply?
supply the lateral portion of the putamen and the posterior internal capsule
stroke in the lenticulostriate arteries would present with what signs?
contralateral paralysis
*ABSENCE of cortical signs (such as neglect, aphasia, or visual field loss)
the posterior communicating artery supplies blood to?
supplies blood to thalamus, optic chiasm, and regions of the hypothalamus
what cranial nerve does the posterior communicating artery travel adjacent to?
Pcom travels adjacent to the oculomotor nerve (CN III)
what is a classic Pcom stroke sign?
third nerve palsy (ptosis, down and out pupil, and mydriasis on the ipsilateral side)
what do the vertebral arteries arise from
subclavian arteries
what are the branches of the vertebral arteries
1) anterior spinal artery
2) PICA and AICA
3) basilar
where do the 2 vertebral arteries join to form the basilar artery
at the junction between the pons and medulla
what are the branches of the basilar artery
1) superior cerebellar arteries (SCA)
2) basilar divides into 2 posterior cerebral arteries (PCA)
posterior cerebral artery (PCA) - perfusion and branches
*occipital cortex visual areas
*inferior temporal lobe
*splenium of corpus callosum
*hippocampus
*portions of midbrain
PCA divisions
*P1 is pre-communicating (before posterior communicating artery)
*P2, P3, and P4 are post-communicating
P1 vs. P2 occlusions
*with P1 occlusions, there is distal PCA circulation via Pcom
*with P2 occlusions, there is NO distal perfusion of cortex
clinical signs of a PCA stroke
*CONTRALATERAL homonymous hemianopsia: loss of one half of the visual eye fields
*in-utero strokes are most commonly strokes in the PCA (fetal PCAs)
watershed zones
*regions of the brain that receive dual blood supply branches of 2 major arteries
*2 important watershed zones in the brain:
1. ACA-MCA watershed
2. PCA-MCA watershed
superior cerebellar artery (SCA) supplies?
cerebellar hemispheres and parts of the midbrain
clinical signs of SCA stroke
trigeminal neuralgia (severe pain in the jaw) due to compression of the trigeminal nerve
anterior inferior cerebellar artery (AICA) supplies?
ventral surface of cerebellum and the lateral pons
clinical signs of AICA stroke
*loss of pain and temperature to FACE (ipsilateral) & LIMBS (contralateral)
*LOSS OF HEARING, VERTIGO, and NYSTAGMUS
posterior inferior cerebellar artery (PICA) supplies?
LATERAL MEDULLA, as well as vermal region and inferior lateral surface of the cerebellar hemisphere
clinical signs of PICA stroke
*dysphagia, hoarseness, tongue deviation, loss of gag reflex
*ipsilateral Horner’s syndrome (ptosis, miosis, hemianhidrosis)
*cerebellar ataxia
*decreased pain and temperature from contralateral body, ipsilateral face
lateral medullary (Wallenburg’s) syndrome
PICA STROKE
presents as:
*dysphagia, hoarseness, tongue deviation, loss of gag reflex
*ipsilateral Horner’s syndrome
midbrain blood supply
*PCA primarily (some from SCA)
most common midbrain stroke syndrome
Weber Syndrome:
-midbrain stroke due to occlusion of branches of PCA
-causes ipsilateral CN III palsy & contralateral hemiplegia
Weber Syndrome
*occlusion of PCA
*ipsilateral oculomotor (CN III) palsy
*contralateral weakness/hemiplegia of body and face
pontine blood supply
*basilar artery (paramedian, short, and long branches)
*SCA contributes to rostral pons
example of a pontine syndrome
Locked In Syndrome
Locked In Syndrome
*due to complete occlusion of basilar artery
*pt can move their eyes but nothing else:
-quadriplegia, loss of voluntary facial & mouth & tongue movements, loss of horizontal but not vertical eye movements
medullary blood supply
MEDIAL = anterior spinal artery
LATERAL = PICA
syndrome associated with occlusion to MEDIAL medullary blood supply
Medial Medullary Syndrome of Dejerine:
1. contralateral paralysis (upper & lower limbs)
2. decreased contralateral proprioception
3. ipsilateral hypoglossal dysfunction (tongue deviates ipsilaterally)
*caused by occlusion of anterior spinal artery
all blood is drained from the brain by what vein
INTERNAL JUGULAR vein
bridging veins
*veins that drain underlying neural tissue, penetrate the dura mater, and empty into the dural sinuses
note - subdural hematomas classically result from tearing of the bridging veins
acute, subdural hematomas most commonly develop after rupture of ?
rupture of a bridging vein
superior sagittal sinus
*largest venous sinus
*CSF return to venous drainage through bridging veins (arachnoid granulations)
issues associated with the superior sagittal sinus
1) occlusion = increased intracranial pressure (potentially fatal)
2) shearing = subdural hematoma
3) superior sagittal sinus thrombosis (SSST) = stroke related to hypercoagulability
cavernous sinus
*venous sinus that drains the eyes and superficial cortex
*ICA and CNs III, IV, V1, V2, and VI pass through
cavernous sinus thrombosis
*thrombosis secondary to bacterial infection in the face
*can cause headache, proptosis, and ipsilateral CN deficits
