The posterior cerebral arteries (PCA) are the terminal branches of the basilar artery and supply the occipital lobes and posteromedial temporal lobes.
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Summary
origin: terminal branches of the basilar artery
course: from basilar towards occiput
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main branches
supply: occipital lobes and posteromedial temporal lobes
Gross anatomy
The PCA is divided into four segments:
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P1: pre-communicating segment
originates at the termination of the basilar artery
terminates to the posterior communicating artery (PCOM), within the interpeduncular cistern
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P2: post-communicating segment
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from the PCOM around the midbrain
P2A (anterior): sub-segment courses through the crural cistern
P2P (posterior or ambient): sub-segment courses through the ambient cistern
terminates as it enters the quadrigeminal cistern
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P3: quadrigeminal segment
courses posteromedially through the quadrigeminal cistern
terminates as it enters sulci of the occipital lobe
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P4: cortical segment
within the sulci of the occipital lobe
e.g. calcarine artery, within the calcarine fissure
Branches
collicular (quadrigeminal) artery
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choroidal branches (from P2)
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perforators
anterior thalamoperforator (from PCOM)
posterior thalamoperforator (from P1)
thalamogeniculate perforator (from P2)
peduncular perforator (from P2)
circumflex (long and short)
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cortical branches
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temporal branches
posterior temporal artery
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lateral occipital artery
anterior inferior temporal artery
middle inferior temporal artery
posterior inferior temporal artery
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medial occipital artery
parieto-occipital artery
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Supply
The posterior cerebral artery curls around the cerebral peduncle and passes above the tentorium to supply the posteromedial surface of the temporal lobe and the occipital lobe. The visual cortex responsible for the contralateral field of vision lies in its territory. The macular part of the visual cortex often receives a dual blood supply from the PCA and the MCA, which explains the "macular sparing" phenomenon in some patients following a PCA infarct.
Variant anatomy
fetal posterior cerebral artery: unilateral incidence 10%, bilateral incidence 8%
PCA fenestration: rare
duplicated PCA: rare, fetal origin and normal origin on same side 6