脳底動脈・前下小脳動脈・上小脳動脈

Basilar Artery, Anterior Inferior Cerebellar Artery, Superior Cerebellar Artery

Point

・脳底動脈は前下小脳動脈，上小脳動脈，穿通枝などさまざまな分枝をしながら脳幹腹側を上行し，脳幹，小脳，内耳などへ血流を供給している．

・脳底動脈は胎生期に2本の縦走動脈が癒合して1本になるため，このプロセスが不完全であると窓形成を生じる．

・前下小脳動脈は，後下小脳動脈と連携しながら小脳の腹側，尾側を中心に灌流するが，脳幹や内耳器官にも分枝している．

・上小脳動脈は必ず存在し，小脳半球の頭側を主に灌流するが，脳幹，小脳虫部，小脳深部へも血流を送っている．

　The basilar artery（BA）is formed by the fusion of two longitudinal arteries, and incomplete development may lead to BA fenestration. The BA provides many short perforating arteries and long lateral pontine arteries to the brain stem. The anterior inferior cerebellar artery（AICA）usually branches from the proximal third of the BA and primarily perfuses the ventral, inferior and lateral aspect of the cerebellum and inner ear organ. However, there are many variations to the AICA that depend on the degree of posterior inferior cerebellar artery development. The superior cerebellar artery（SCA）branches into not only to the rostral, ventral aspect of the cerebellar hemisphere, but also to the deeper cerebellar nucleus and brain stem. Duplications within this vessel are frequently identified, but it is not missing.