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The trigeminal artery is an artery that supplies the basilar artery with blood during human embryonic development. Normally, the trigeminal artery involutes after the formation of the posterior communicating artery. However, in some cases, the artery persists into adulthood and can cause medical complications, including intracranial aneurysms.

Normal development
The trigeminal artery arises from the primitive internal carotid artery during development, when the embryo is approximately 6 weeks old. The trigeminal artery then anastomoses with the basilar artery. As the internal caudal artery branches more caudally] to form the [[posterior communicating artery, the trigeminal artery becomes less important in supplying blood and ultimately involutes.

Persistent trigeminal artery
In around 0.1 to 0.6% of individuals, as sampled by magnetic resonance angiography, the trigeminal artery fails to involute and remains in the adult brain, in a condition called persistent trigeminal artery. Knowledge of a persistent trigeminal artery may be important in certain brain surgeries, as the condition is rare and an accidental cut to the artery could lead to hemorrhage. A persistent trigeminal artery is associated with an increased risk of aneurysm, though some studies have suggested that this finding may be an effect of selection bias, as most individuals do not undergo the tests necessary to identify the condition. However, persistent trigeminal artery has been associated with vertebrobasilar insufficiency, brainstem ischemia, and carotid cavernous fistulae.