Blood Supply, Hemorrhage and Herniation of the Brain Flashcards
Border zones
Area between arteries
Susceptible to damage under conditions of sudden systemic hypotension or hypoperfusion
Anterior cerebral artery
Supplies most of the medial and superior surface of the frontal and parietal lobes
Middle cerebral artery
Supplies lateral surface of frontal and parietal lobes and the superior part of temporal lobe
Posterior cerebral artery
Supplies the occipital lobe and the inferior parietal lobe
Segments of anterior cerebral artery
A1- precommunicating segment- ICA to anterior communicating artery
A2- infracallosal segment- anterior communicating artery to where rostrum and genu of corpus callosum meet
A3- precallosal segment- arches around the genu of corpus callosum, ends when vessels turn caudal
A4- supracallosal- superior to corpus callosum
A5- postcallosal- caudal to corpus callosum
Segments of middle cerebral artery
M1- sphenoidal or horizontal- ICA to the bifurcation at insula
M2- insular- bifurcation at insula to circular sulcus of insula
M3- opercular- circular sulcus of insula to external surface of lateral fissure
M4- cortical- on the cortex
Segments of posterior cerebral artery
P1- basilar bifurcation to posterior communicating artery
P2- posterior communicating artery to around the midbrain
P3- quadrigeminal- segment within the quadrigeminal cistern
P4- cortical segment
Parts of the internal carotid artery
Cervical- bifurcation to carotid canal, anterior to transverse processes of upper 3 vertebrae
Petrous- carotid canal in petrous part of temporal, upward and medially above foramen lacerum
Cavernous- in the cavernous sinus, surround by sympathetic plexus, CN III, IV, VI and V1
Cerebral part
Vertebral artery parts
Cervical- transverse foramina of first 6 cervical vertebrae
Atlantic- perforates the dura and arachnoid, pass through foramen magnum
Intracranial- in the cranium, unite at the caudal border of pons to form basilar artery
Cranial nerves association to arteries CN II, III and VI
CN II is near ICA, anterior cerebral and anterior communicating artery
CN III is near posterior cerebral a, superior cerebellar a, and posterior communicating a
CN VI is near labyrinthine and AICA
Circle of willis
A ring of 9 arteries supplying blood to the cerebral hemispheres 2 anterior cerebral a. 2 internal carotid a. 2 posterior cerebral a. Anterior communicating artery 2 posterior communicating a. Located in the subarachnoid space
Intracerebral (subpial) hemorrhage
Bleeding within brain substance (stroke)
Complication in 2-3% of all head injuries
Source is usually middle cerebral artery
Hypertension or degenerative artery disease is commonly found at autopsy
Causes of herniation syndromes
Hemorrhage Mass/tumor Trauma Abscess Infection Metabolic conditions
Divisions of herniation syndromes
Supratentorial compartment- above the tentorium and divided into right/left by falx cerebri
Infratentorial compartment- below tentorium cerebelli
Tentorial notch- continuation of the supra and infratentorial compartment
Subfalcine herniation
Also called a cingulate or falcine or falx herniation
Supratentorial compartment has mass/lesion- displaces brain tissue under the falx cerebri
May compress the ACA- frontal/parietal lobes affected
May evolve into a transtentorial herniation
Transtentorial herniation
Also called central herniation
Brain displaced downward toward tentorial notch
Comprises the upper brainstem, CN III and possibly even lower structures. May compress basilar artery and posterior cerebral arteries
Decorticate rigidity
Decerebrate rigidity
Uncal herniation
Uncus and frequently portions of the parahippocampal gyrus are extruded over the edge of tentorium cerebelli and through the tentorial notch
- Impinge on midbrain
- Can damage cerebral peduncle & oculomotor nerve and cause motor deficits on opposite side of body
Tonsillar herniation
Cerebellar tonsil through foramen magnum
Compression of the medulla and upper cervical spinal cord
Vertebrobasilar insufficiency
Reduced blood flow to brain from vertebral arteries
Can be caused by extreme hyperextension of the head or extreme head rotation
Subclavian steel syndrome
Occlusion of subclavian artery proximal to the vertebral artery. Blood is stolen from vertebral circulation to supply upper limbs
Trigeminal nerve is by which arteries
Superior cerebellar artery
Facial nerve is by which arteries
Anterior inferior cerebellar artery
Damage to border zone b/w anterior cerebral and middle cerebral arteries will cause what
Motor, sensory deficits
Language issues
Behavioral problems
Damage to posterior border zone b/w posterior cerebral and middle cerebral artery will cause what
Visual and language problems
What artery since right up against corpus callosum
Pericallosal artery
What artery is around cingulate gyrus
Callosomarginal artery
Anterior spinal artery supplies what
Medial aspect of medulla
Posterior inferior cerebellar artery PICA supplies what
Lateral aspect of medulla Medial/inferior vestibular nucleus Accessory cuneate nucleus Solitary tract/nucleus Dorsal motor nucleus of vagus (autonomics) Spinal trigeminal tract/nucleus Rubrospinal tract ALS Nucleus ambiguous (motor tract)
Anterior inferior cerebellar artery supplies what
Cochlear nuclei (CNVIII)
Posterior spinal artery supplies what
Dorsal aspect of medulla
What arteries branch off anterior spinal artery to supply medulla and what do they supply
Sulcal arteries
Pyramid (motor) tract
Medial lemniscus (sensory tract)
Hypoglossal nucleus
Blood supply to pons is via
Branches off basilar artery and superior cerebellar artery in more rostral regions
Blood supply to midbrain is via
Posterior cerebral artery branches
P1 anteromedial segment of PCA supplies
Medial portion of midbrain Oculomotor nucleus Medial longitudinal nucleus Substantia niagra Red nucleus Parts of oculomotor nerve
Thalamogeniculate branches of P2 supply what
Lateral and medial geniculate nuclei in forebrain
Lenticulostriate arteries supply what and is a branch off what artery
Internal capsule
Branch of middle cerebral artery
Epidural hematoma information
Bleeds into potential space of skull and dura
Common site: pterion or squamous temporal bone
Source: middle meningeal artery
Clinical- momentary unconsciousness followed by lucidness for a few hours to 1-2 days then unconsciousness
Subdural hematoma information
B/w dura and arachnoid
Seen when head strikes a fixed object
Venous source of bleeding- usually cortical veins opening into superior sagittal sinus
Clinical- slower accumulation of blood due to pressure and often self limiting
Lumbar puncture can cause subdural hematoma
Kernohan phenomenon
Variation of uncle herniation that shifts the midbrain
Still hits oculomotor nerve on same side but compresses cerebral peduncle on OPPOSITE side, giving motor deficits on the same side
Long circumferential branches of basilar artery supply
Lateral, superolateral pons Facial nerve, facial motor nucleus Spinal trigeminal tract/nucleus Mesencephalic nucleus/tract ALS
Paramedian branches of basilar artery supply
Medial pons Corticospinal fibers Medial lemniscus Abducens nerve/nucleus Medial longitudinal fasciculus
