In the endovascular treatment of cerebral aneurysms, these flexible tubes are introduced through an access point to the arteries (typically through an artery in the groin) and moved through the arteries into the patient’s carotid artery (the principal artery in the neck). Once positioned in the carotid artery, the guide catheter functions as a working channel through which smaller devices, like microcatheters, may be introduced into the brain.