The posterior cerebral artery arises near the intersection of the posterior communicating artery and the basilar artery and connects with the ipsilateral middle cerebral artery (MCA) and internal carotid artery via the posterior communicating artery (PCommA).
The PCA is divided into four segments:
- Precommunicating part; P1 segment: from it origin at the termination of the basilar artery to posterior communicating artery (PCOM), within interpeduncular cistern.
- Postcommunicating part; P2 segment: from the PCOM around the mid-brain, divided into P2A (anterior) and P2P (posterior) sub-segments. P2A is within crural cistern which then bridges to the P2P segment in ambient cistern (thus ambient segment)
- P3 segment
- P4 segment
Note that it seems that P3 and P4 segment seems to have different meanings between Terminologia Anatomica and neurosurgical/neuroradiologic textbooks :
In the Terminologia anatomica:
- Lateral occipital artery; P3 segment: lateral terminal branch of the posterior cerebral artery that passes to the basilar surface of the posterior part of temporal lobe
- Medial occipital artery; P4 segment: medial terminal branch of the posterior cerebra artery passing to the medial surface of the occipitallobe.
In neurosurgical/neuroradiologic textbooks:
- P3 segment; quadrigeminal segment: extends in a medial and posterior direction ~ 40mm in length. The PCA often divides into its two terminal branches, the calcarine and parieto-occipital arteries between
- P4 segment; cortical segment, that includes two main terminal branches of the PCA, the calcarine artery and parieto-occipital artery.