The anterior circulation is the blood supply to the
anterior portion of the brain, including most of the
supratentorial structures excluding the occipital
lobes.
The anterior circulation is supplied by the internal
carotid arteries which each divide into two the large
terminal branches, the anterior cerebral and middle
cerebral arteries. Due to the anastomotic circle of
Willis, the anterior circulation connects via the
posterior communicating arteries to the posterior
circulation.
TABLE 9.1
Symptoms and Signs of Posterior Circulation
Ischemia.
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Dizziness or vertigo (accompanied by other
symptoms)
Difficulty ambulating
Loss of balance
Ataxia
Inability to maintain erect posture
Upper extremity hypotonia
Blindness
Blurred vision
Diplopia
Hemianopia
Bilateral visual field defects
Nystagmus
Poorly reactive pupils
Difficulty focusing
Difficulty reading
Memory loss
Somnolence