Origin
The development of the PCA in fetal brain comes relatively late and arises from the fusion of several embryonic vessels near the caudal end of the PCommA supplying the mesencephalon and diencephalon of the fetus. The PCA begins as such, as a continuation of the PCommA in the fetus with only 10–30% of fetuses having a prominent basilar origin.
The fetal carotid origin of the PCA usually regresses as the vertebral and basilar arteries develop with the PCommA reducing is size. In most adults, the PCA sources from the anterior portion of the basilar artery. Only about 19% of adults retain PCommA dominance of the PCA with 72% having dominant basilar origin, and the rest being equal prominence or exclusive sources for suppyling the PCA.
Read more about this topic: Posterior Cerebral Artery
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