![]() ![]() It does not, to my knowledge, ever extent its inferior cortical supply to the posterolateral medulla. Depending on hemodynamic balance, a more prominent AICA will continue inferiorly to capture the inferior cerebellar hemisphere and, potentially, the inferior vermis, due to relative hypoplasia of the PICA, corresponding to the aforementioned AICA-PICA variant. It gives a branch to the inner ear (Internal Auditory Canal branch), which will form a loop within the IAC more often than not. Its supply, therefore, includes portions of pons and the anterior cerebellum. Classically, it arises from the mid-basilar, and sweeps posterolaterally, covering ventral to pons in the prepontine cistern, to head posterolaterally within the cerebellopontine angle along the anterior cerebellar surface. Origin and course: The AICA is a highly variable artery in its position along the basilar axis, and extent of cortical territory. An “otic” artery - segmental anteroposterior anastomotic artery similar to persistent trigeminal and hypoglossal - has been postulated to traverse the inner ear to connect with the carotid - but has never been conclusively demonstrated to exist. The reverse (PICA-AICA) is just as legitimate, with a small AICA and large PICA cortical supply. Dominance of AICA produces the well-known AICA-PICA variant. Any variation is possible, depending on which trunk dominates the cortex. The same goes for the cortical territory as well, where hemodynamic balance exists between SCA, AICA, and PICA in extent of cortical supply. This concept helps explain most variations seen within the arrangement - a duplicated AICA, for example, represents co-persistence of two adjacent trasverse vessels with cortical territory. The dominant vessels which emerge are thus named AICA, SCA, and PICA. It seems that hemodynamics favor selection of a dominant vessel (or two) for this role, and so most transverse vessels remain confined to supply of the brainstem (perforators). One can think of the early vertebrobasilar system as a longitudinal vessel (basilar) with a myriad transverse vessels, each having the potential to become SCA or AICA by capturing the cortical territory of the developing cerebellum. It develops as a branch of the longitudinal neural system, a forerunner of the basilar artery. Anterior Inferior Cerebellar Artery (AICA)Įvolution and Embryology: Unlike PICA, which can be conceptualized as a cervical artery impressed into posterior fossa service by expanding needs of the cerebellum, the AICA is a true cerebellar and brainstem artery. ![]()
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