Posterior Cerebral Artery Branches

Posterior Cerebral Artery (PCA)

The precommunicating segment of the PCA (P1) extends from the basilar bifurcation to the origin of the posterior communicating artery (PCommA). Its course lies within the inter-peduncular cistern, which is demarcated by the clivus and the two cerebral peduncles. The oculomotor nerve, after its emergence from the brain stem, runs between the PCA and the superior cerebellar artery. The postcommunicating segment (P2) curves laterally and backward around the crus cerebri and reaches the posterior surface of the midbrain at an intercollicular level.

The precommunicating and postcommunicat-ing segments are together referred to as the pars circularis of the PCA. (Alternatively, the pars circularis may be divided into three segments— interpeduncular, ambient, and quadrigeminal— named after the cisterns they traverse.) Distal to the pars circularis of the PCA is the pars terminalis, which divides above the tentorium and caudal to the lateral geniculate body to form its terminal branches, the medial and lateral occipital arteries.

Pars circularis. The precommunicating segment gives off fine branches (posteromedial central arteries) that pierce the interpeduncular perforated substance to supply the anterior thalamus, the wall of the third ventricle, and the globus pallidus. The postcommunicating segment gives off fine branches (posterolateral central arteries) to the cerebral peduncles, the posterior portion of the thalamus, the colliculi of the mid brain, the medial geniculate body, and the pineal body. Further branches supply the posterior portion of the thalamus (thalamic branches), the cerebral peduncle (peduncular branches), and the lateral geniculate body and choroid plexus of the third and lateral ventricles (posterior choroidal branches). Pars terminalis. Of the two terminal branches of this terminal portion of the PCA, the lateral occipital artery (together with its temporal branches) supplies the uncus, the hippocampal gyrus, and the undersurface of the occipital lobe. The medial occipital artery passes under the splenium of the corpus callosum, giving off branches that supply it (dorsal branch to the corpus callosum) as well as the cuneus and pre-

cuneus (parieto-occipital branch), the striate cortex (calcarine branch), and the medial surfaces of the occipital and temporal lobes (occipi-totemporal and temporal banches), including the parasagittal portion of the occipital lobe.

Precommunicating — segment (P1) \

Basal area of anterior choroidal a

Postcom-municating

Posterior communicating a.

Middle cerebral a.

Precommunicating — segment (P1) \

Posterior communicating a.

Middle cerebral a.

Basal area of anterior choroidal a

Postcom-municating segment (P2)

Postero-medial central arteries

Posterior Cerebral Artery Branches

Thalamic branch

Branch to corpus callosum

Temporal branch segment (P2)

Postero-medial central arteries

Medial occipital a

Undersurface of cerebellum (showing arteries)

Lateral occipital a.

Calcarine branch

Posterior cerebral artery

(green = peripheral branches)

Thalamic branch

Branch to corpus callosum

Temporal branch

Anterior cerebral a.

Middle cerebral a. (peripheral branches)

Middle cerebral a. Anterior (central branches) choroidal a.

Superior cerebellar a.

Posterior cerebral a. (peripheral branches)

Posterior Posterior cerebral a. inferior (central branches) cerebellar a.

Pf i

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