Blood Supply, Hemorrhage, & Herniation Flashcards
What are the four parts of the ICA?
Cervical part, petrous part, cavernous part, cerebral part
What are the three parts of the vertebral a?
Cervical part, atlantic part, intracranial part
What is vertebrobasilar insufficiency?
decreased blood flow of vertebral a to the brain
What can cause vertebrobasilar insufficiency?
Extreme hyperextension of the head, extreme head rotation, subclavian steal syndrome
What forms the circle of willis?
ICA (x2), ACA (x2), anterior communicating a (x1), posterior communicating a (x2), PCA (x2)
Which artery is not part of circle of willis?
MCA
Which vessels can compress CN II?
ICA, ACA, and anterior communicating a
Which vessels can compress CN III?
Sandwiched between PCA and superior cerebellar a
Which vessels can compress CN V?
Superior cerebellar a (aberrant loops)
Which vessels can compress CN VI?
Labyrinthine a and AICA
Which vessels can compress CN VII?
AICA (aberrant loops)
Where does the ACA supply in the brain?
Medial and superior surfaces of frontal/parietal lobes
Where does the MCA supply in the brain?
Lateral surface of frontal/parietal and superior surface of temporal lobe
Where does the PCA supply in the brain?
Occipital lobe and inferior temporal lobe
What deficits can be seen in the border zone between ACA/MCA?
Motor, sensory, language, and behavioral deficits
What deficits can be seen in the border zone between MCA/PCA?
Vision and language problems
What are the segments of the ACA?
A1 - precommunicating A2 - infracallosal A3 - precallosal A4 - supracallosal A5 - postcallosal
What are the segments of the MCA?
M1 - sphenoidal/horizontal
M2 - insular
M3 - opercular
M4 - cortical
What are the segments of the PCA?
P1
P2
P3 - quadreminal segment
P4 - cortical segment
Which arteries supply different parts of the medulla?
Anterior spinal a does the medial aspect
PICA does the lateral aspect
AICA does the cochlear nuclei (CN VIII)
Posterior spinal a does the dorsal aspect
What arteries supply the pons?
Branches off the basilar a
Which arteries supply different parts of the pons?
Paramedial branches supply medial aspect
Long circumferential branches supply lateral aspect
What arteries supply the midbrain?
Mostly branches from posterior cerebral a
Which arteries supply different parts of the midbrain?
Branches of P1 supplies anteromedial part of midbrain
Branches of P3 supplies lateral structures
Which arteries supply different parts of the forebrain?
Branches of P2 supply LGN and MGN
Lenticulostriate arteries supply internal capsule
Anterior choroidal a supplies internal capsule
Which arteries supply different parts of the spinal cord?
Posterior spinal arteries supply dorsal/posterior columns
Sulcal branch of anterior spinal a supplies dorsal and ventral horn
Anterior spinal a and posterior spinal a do the corticospinal tract
What is usually the source of bleeding for intracerebral hemorrhages? (hemorrhagic strokes?)
MCA (usually causes midline shift due to all the bleeding)
What compartment is above the tentorium cerebelli?
The supratentorial compartment, divided into R/L by falx cerebri
What compartment is below the tentorium cerebelli?
The infratentorial compartment
What is the tentorial notch?
Continuation of the supra and infratentorial compartments
What is a subfalcine herniation?
Occurs in the supratentorial compartment when brain tissue is displaced under the falx cerebri.
What can a subfalcine herniation compromise?
May compress ACA (frontal/parietal lobe), could compromise lower limbs
What is a transtentorial herniation?
Brain displaced downward toward tentorial notch.
What can a transtentorial herniation compromise?
Compromises upper brainstem and CN III. May compress basilar a and PCAs, associated with decorticate rigidity -> decerebrate rigidity
What is an uncal herniation?
Uncus (and sometimes portions of parahippocampal gyrus) extrude over edge of tentorium cerebelli and through tentorial notch
What can an uncal herniation compromise?
Can impinge on midbrain
What is a tonsillar herniation?
Cerebellar tonsils through foramen magnum
What can a tonsillar herniation compromise?
Compression of medulla and upper cervical spinal cord (cardiac and respiratory centers)