blood supply, hemorrhage, herniation Flashcards
what are the parts of the ICA
- cervical
- petrous
- cavernous
- cerebral
cerebral branches off into ophthalmic A, anterior cerebral, middle cerebral, and posterior communicating branch
what are the parts of the vertebral A.
- cervical (C1-C6)
- atlantic (pierces dura and arachnoid matter and atlantooccipital membrane to enter foramen magnum)
- intracranial (foramen magnum–> basilar A. at lower pons)
what parts of the circle of willis create the anastomotic connections
- anterior cerebral A.
- anterior communicating
- posterior cerebral A.
- posterior communicating
*coming from vertebral and ICA
what nerves are compressed from the blood supply to the brain (cerebrum and cerebellum)
CN 2 - 7 *except 4
2- ICA and ACA 3- SCA and PCA 5- aberrant branches of SCA 6-AICA and IAA 7- aberrant branches of AICA
what is the blood supply to the cortex
ACA- superior and medial frontal and pariteal lobes
MCA- lateral frontal and parietal lobes and superior temporal lobe
PCA- inferior temporal lobe and occipital lobe
what are the border zones of the cortical blood supply? (watershed infarct spots)
-areas between arteries in which are at high risk for damage due to sudden hypotension or hypoperfusion
- anterior (between ACA and MCA) = motor and sensory deficits to LE
- posterior (between MCA and PCA) = vision and language deficits
what are the 5 parts of the Anterior cerebral A.
A1
A2 (infracollosal - from communicating branch to where rostral part meets genu)
A3 (precollosal- around bend of genu)
A4 (supracollosal- above the body of corpus callosum)
A5 (postcollosal) terminal branches going to cortex that DO NOT anastomose with other branches
what are the 2 arteries off the ACA that make up most of A3 and A4
pericallosal A (above corpus callosum) callasomarginal A. (above cingulate gyrus)
what are the 4 parts of the MCA
M1-. horizontal (gives of lenticulostriate A. s)
M2.- insular
M3 - opercular
M4 (cortical) on cortex
what are the 4 parts of the PCA
P1 - basically bifurcation to posterior communicating
P2 - posterior communicating - around midbrain
P3 - in quadrigeminal cistern
P4 - on cortex
what is the blood supply to the medulla
*vertebral A. and basilar A.
- anterior spinal A. [ medial supply including the hypoglossal nucleus, medial lamniscus, pyramids]
- posterior spinal A. [ lower medulla, superior portion including the fasiculus gracilis and cunteuas ]
- AICA - [upper medulla - dorsal and ventral cochlear nuclei]
- PICA - [ upper medulla laterally]
what A. is responsible for medial medullary syndrome
anterior spinal A.
what A. is responsible for lateral medullary syndrome ( wallenburgs syndrome)
PICA
what is the blood supply to the pons
Basilar A. and AICA
- paramedian branches from basilar A. (pontine A.s) supply medial aspect
- long circumferential branches from basilar and AICA supply lateral aspect
what is the blood supply to the midbrain
- PCA, SCA, and basilar A.
1. anteromedial paramedian branches of basilar bifurcation and PCA (P1) - medial midbrain
2. quadrigeminal A. and SCA - inferior colliculus
3. quadrigeminal A. and posterior medial choroidal branches - superior colliculus - quadrigeminal A. comes from PCA
- posterior choroidal A. comes from P2 segment of PCA
what A. is responsible for medial pontine syndrome
paramedian branches from the basilar A. (pontine A.s)
what A. is responsible for the lateral pontine syndrome
long circumferential branches from basilar and AICA
_____ infarcts result in contralateral homonymous hemianopia and contralateral hemisensory loss. There may be some disturbance of higher function, such as altered memory or speech or cortical blindness.
Posterior cerebral artery
Occlusion of the _____ produces lesions of both posterior cerebral arteries and high brain stem lesions that may lead to ‘a locked in’ state – where the upper brain stem lesion prevents the conscious brain having any control over bulbar function or the limbs, though some control of eye movements can remain.
basilar artery
what are the terminal branches of the basilar A.
2 posterior cerebral A. s
what causes Webers syndrome (midbrain syndrome) which is ipsilateral CN III palsy with contralateral hemiplegia or hemiparesis
PCA due to anteromedial branches from the P1 segment of PCA supplying medial midbrain
what is the blood supply to the forebrain
**MCA; ICA; PCA
- thalamogeniculate branches of the PCA
[thalamus; medial and lateral geniculate bodies] - anterior choroidal A. (from M1 of MCA or ICA)
[ optic tract; hippocampal formation; parts of internal capsule] - lenticulostriate A.s (from MCA)
[part of internal capsule]
what artery supplies most the diencephalon
PCA (branches such as the thalamogenticulate A.)
what is the blood supply to the spinal cord
- paired posterior spinal A.s (from PICA)
- posterior 1/3 of spinal cord
- fasiculus gracilis and cuneuatus [ white matter on dorsal side]
- legs of the cortical spinal tract - single anterior spinal A. (from vertebral A. )
- anterior 2/3 of spinal cord
- gives off sulcal A.s that supply the dorsal and ventral horns of gray matter - arterial vasocorona supplies peripheral lateral aspect
* reinforced by segmental (radicular arteries which come from different sources down the spinal cord)
what is the side effect of sulcal A. occlusion ? where does this artery originate ?
*from the anterior spinal A.
one sided medullary or spinal cord affect depending on level.
*one sided bc of stair step pattern
what supplies the legs of the cortical spinal tract ? arms?
legs = the Posterior spinal A.
arms=
what artery connects the anterior and posterior spinal artery allowing an anastamotic connection to supply all around the cord
arterial vasocorona
(AVC)
helps supply outer ring of the spinal cord all the way around
what are the potential spaces of the meninges? and what is the true space and what does it contain?
potential
- epidural (between periosteum and periosteal dura)
- subdural (between meningeal dura and arachnoid)
true
- subarachnoid (between arachnoid and pia)
- contains CSF, circle of willis arteries, and veins
what is the major trauma site for an epidural hematoma? blood supply of bleed? common symptoms ? and CT presentation? tx?
- trauma to pterion of skull
- blood supplied by MMA
- momentary unconsciousness, long period of lucidness, followed by more unconsciousness
- if not caught = possible death
- smooth lens shaped hematoma on CT
- tx: surgery
what does the MMA supply
mostly calvaria (bone) not dura
what is the blood supply for a subdural hematoma? clinical presentation ? tx? CT presentation?
- venous blood supply (usually cerebral veins opening into superior sagital sinus)
- slow blood accumulation bc of venous pressure, often self-limiting
- symptoms depend on trauma site
- tx: surgery
- CT: crescent / jagged hematoma
causes of subarachnoid hemorrhage ? source of bleeding? clinical presentation? survival rate?
- severe head trauma or more likely aneurysm rupture
- blood supply: cerebral A.s (circle of willis aneurysm rupture usually; ACA and PCA)
- immediate “worst headache of life”
- massive bleeding into CSF space, headache, deteriorating consciousness
- 50% die
*WEAK BLOOD VESSEL RUPTURE ON SURFACE OF BRAIN = HEMORRAGIC STROKE
T/F
there are 2 types of strokes. an ischemic stroke and hemorrhagic stroke
true
cause of intracranial (subpial) hemorrhage ? blood source? what increases your risk of this event occurring?
- hemorrhagic stroke inside the brain tissue
- casues: knife wound, bullet, stroke
- blood source: usually middle cerebral A. (MCA)
- risk increased by HTN and degenerative arterial disease
what is the cause of herniation syndromes in the brain ? what are the 3 compartments they can occur in ?
-caused by increased intracranial pressure (hemorrhage, tumor, infection, etc)
- supratentorial compartment (above tentorium cerebelli and separated in R and L by falx cerebri)
- infratentorial compartment (below the TC)
- tentorial notch (continuation/space between the supra and infratentorial compartment ?
what is a subfalcine herniation ? where is the location of the causative lesion? what is the effect of the brain? what structures does it damage? CT presentation ?
*aka falcine/ falx/ cingulate herniation
- supratentorial compartment
- pushes cingulate gyrus under falx cerebri into opposite supratentorial compartment
- may compress the ACA affecting the frontal and parietal lobes [ LE motor/sensory of homunculus]
- may evolve into transtentorial herniation if not treated
- CT: bowed falx cerebri with white spots of bleeding seen
what is a transtenorial herniation? what structures does it compromise? possible side effects?
*aka central herniation
- supratenorial compartment
- hernation of the brain downward towards the tectorial notch pass tentorial cerebelli
- compromises the midbrain and CN3
- can compress the basilar A. and PCA’s leading to vision deficits from occipital lobe dysfunction
- decorticate rigidity
- decerebrate rigidity
**BADDDD
what is an uncle herniation ? what does it effect? what are the 2 types
- supratentorial compartment
- uncus (and usually parahippocampal gyrus; from temporal lobe of forebrain) pushed over edge of tentorium cerebelli and towards the center towards the tentorial notch
- impinges the midbrain
- over tentorial cerebelli and notch and compression of ipsilateral midbrain structure causeing damage to cerebral peduncle with motor tracts and CN 3
* leads to CONTRALATERAL hemiplesia (paralysis) , and ipsilateral CN 3 deficits (eye movement problems) - kernohan syndrome
- herniation pushes midbrain to side and damages ipsilateral CN3 and contralateral cerebral peduncles
* leads to ipsilateral CN 3 deficits and IPSILATERAL hemiplesia
what is a tonsillar herniation ? what does it cause?
*infratentorial compartment
- movement of cerebellar tonsils through foramen magnum
- causes medulla and upper spinal cord compression
- can lead to heart and respiratory issues there sudden herniation can = sudden death
