Corpus: Posterior cerebral artery

The posterior cerebral artery, or PCA for short, is a branch of the basilar artery and is one of the three main arterial vessels of the brain.

The paired posterior cerebral artery arises in the cerebral arterial circle from the division of the unpaired basilar artery. It is connected to the middle cerebral artery on both sides by an arterioarterial vascular anastomosis, the posterior communicating artery. The cerebral vessel runs around the pedunculi cerebri into the cisterna ambiens, then through the incisura tentorii onto the caudal surface of the temporal lobe and along the parahippocampal gyrus to the occipital lobe.

2.1. Segments

A distinction is made between four segments of the posterior cerebral artery, whereby the P1 segment is separated from the P2 segment by the junction of the posterior communicating artery - hence they are called the pre-communicating and post-communicating segments.

• P1: Pre-communicating segment: It runs through the cisterna interpeduncularis.
• P2: Postcommunical segment: It runs through the cisterna ambiens.
• P3: Quadrigeminal segment: It runs through the quadrigeminal cistern.
• P4: Terminal segment

In the literature, the P3 segment is sometimes also equated with the lateral occipital artery and the P4 segment with the medial occipital artery.

2.2. Topography

The posterior cerebral artery is in close topographical relation to the cerebral crura of the midbrain and to the oculomotor nerve.

2.3. Branches

Various central, choroidal and cortical branches can be distinguished in the posterior cerebral artery. As with other cerebral arteries, the individual anatomy can be varied.

2.3.1. Central branches

They are also known as perforating branches or ganglionic branches.

• Arteria thalami perforans (P1)
• Arteria collicularis (P1)
• Arteriae circumferentiales breves (P1)
• Arteriae centrales posteromediales (P1)
• Arteriae centrales posterolaterales (P2)
• Ramus thalamogeniculatus (P2)
• Rami pedunculares (P2)

2.3.2. Choroidal branches

• Rami choroidei posteriores mediales (P2)
• Rami choroidei posteriores laterales (P2)

The medial and lateral posterior choroidal rami can also branch off from the posterior cerebral artery with a common trunk as the posterior choroidal artery.

2.3.3. Cortical branches

The cortical branches supply areas of the cerebral cortex.

• Rami temporales anteriores (P3)
• Rami temporales posteriores (P3)
• Lateral occipital artery (P3)
• Medial occipital artery (P4)
  • Ramus calcarinus
  • Ramus parietooccipitalis
  • Posterior pericallosal artery

2.4. Supply area

The posterior cerebral artery supplies the occipital lobe, the basal surface of the temporal lobe, the hippocampus, the thalamus and the posterior sections of the hypothalamus. The artery also sends branches to the choroid plexus of the lateral ventricles.

2.5. Norm variant

The so-called foetal posterior cerebral artery is a normal variant that occurs frequently (20-30%). In this case, the vessel is primarily fed via the internal carotid artery.

Occlusion of the posterior cerebral artery leads to posterior infarction. A unilateral occlusion is accompanied by visual field loss on the opposite side (homonymous hemianopsia). The rare bilateral occlusion results in cortical blindness. Occlusion of individual branches can lead to very different neurological syndromes, e.g. thalamic syndrome if the central branches are affected.