posterior cerebral artery

The posterior cerebral arteries (PCA) are the terminal branches of the basilar artery and supply the occipital lobes and posteromedial temporal lobes.

Summary

Gross anatomy

The PCA is divided into four segments:

  • P1: pre-communicating segment
  • P2: post-communicating segment
    • 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
  • P3: quadrigeminal segment
  • P4: cortical segment
    • ​within the sulci of the occipital lobe
    • e.g. calcarine artery, within the calcarine fissure
Branches
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 origin of PCA: unilateral incidence 10%, bilateral incidence 8%
  • PCA fenestration: rare
  • duplicated PCA: rare, fetal origin and normal origin on same side