====== P2 segment Posterior cerebral artery ======

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ambient segment(P2)

● lateral post. choroidal (most from P2)

● thalamogeniculate thalamoperforators (2nd of 2 groups of posterior thalamoperforating
aa.) ⇒ geniculate bodies + [[pulvinar]]

● anterior temporal (anastamoses with anterior temporal br. of MCA)

● posterior temporal

● parieto-occipital

● calcarine

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PCA from origin of p-comm to the origin of inferior temporal arteries(AKA ambient,post-communicating, perimesencephalic), P2 traverses the ambient cistern, hippocampal, anterior temporal, peduncular perforating, and medial posterior choroidal arteries arise from P2.
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P2 segment of the [[posterior cerebral artery]]: from the PCOM around the [[midbrain]], divided into P2A (anterior) and P2P (posterior) sub-segments. 

P2A is within [[crural cistern]] which then bridges to the P2P segement in [[ambient cistern]] (thus ambient segment)
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The [[pterional approach]] exposed the anterior half of the P2a segment. The [[subtemporal approach]] revealed the P2a segment, but its exposure was restricted by its localization in the [[ambient cistern]]. Via the occipital interhemispheric transtentorial approach, the P2p segment was visible and could be manipulated. When the posterior half of P2a segment was high on a coronal view of magnetic resonance imaging, it was extremely hard to access via any approach.

A surgical strategy for the P2 aneurysm can be planned with accurate prediction of the aneurysm location. When the localization of an aneurysm on the posterior half of P2a segment is high, a resection of brain tissue may be required
((Terasaka S, Sawamura Y, Kamiyama H, Fukushima T. Surgical approaches for the
treatment of aneurysms on the P2 segment of the posterior cerebral artery.
Neurosurgery. 2000 Aug;47(2):359-64; discussion 364-6. PubMed PMID: 10942008.
)).

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