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

• origin: terminal branches of the basilar artery
• course: from basilar towards occiput
• main branches
  • posterior communicating artery
  • medial and lateral posterior choroidal arteries
  • calcarine artery
• supply: occipital lobes and posteromedial temporal lobes

Gross anatomy

The PCA is divided into four segments:

• P1: pre-communicating segment
  • originates at the termination of the basilar artery
  • terminates to the posterior communicating artery (PCOM), within the interpeduncular cistern
• 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
  • ​courses posteromedially through the quadrigeminal cistern
  • terminates as it enters sulci of the occipital lobe
• P4: cortical segment
  • ​within the sulci of the occipital lobe
  • e.g. calcarine artery, within the calcarine fissure

Branches

• posterior communicating artery
• collicular (quadrigeminal) artery
• choroidal branches (from P2)
  • medial posterior choroidal arteries
  • lateral posterior choroidal arteries
• perforators
  • anterior thalamoperforator (from PCOM)
  • posterior thalamoperforator (from P1)
  • thalamogeniculate perforator (from P2)
  • peduncular perforator (from P2)
  • circumflex (long and short)
• cortical branches
  • temporal branches
    • anterior temporal artery
    • posterior temporal artery
  • lateral occipital artery
    • anterior inferior temporal artery
    • middle inferior temporal artery
    • posterior inferior temporal artery
  • medial occipital artery
    • calcarine artery
    • parieto-occipital artery
  • splenial artery

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