posterior communicating artery
The posterior communicating artery (PCOM or P Comm) makes up the posterior linkage in the circle of Willis.
The PCOM originates from the posterior aspect of the C7 (communicating) segment of the internal carotid artery and extends posteriormedially to anastomose with the ipsilateral posterior cerebral artery and form part of the circle of Willis.
The PCOM gives off many fine, scarcely visible, perforating branches. The largest perforating branch is called the premamillary (or anterior thalamoperforating) artery.
Perforators from the PCOM supply:
- posterior part of the optic chiasm and optic tract
- posterior part of the hypothalamus and mammillary bodies
- part of the thalamus
- fetal origin of posterior cerebral artery: common (see case 1)
- PCOM duplication: rare
- PCOM fenestration: extremely rare
- PCOM hypoplasia: incidence ~35%
- PCOM infundibulum (see case 2)
- anterior choroidal artery origin from PCOM