The basilar artery is the largest cerebral artery, with a diameter of up to 9.6 mm in the initial section and 4.5 mm at the mouth. It leaves the brain in the anterior cranial fossa and is located in the upper part of the spinal cord and medulla oblongata. It flows into the vertebrobasilar foramen. Located near the sigmoid artery. The _Basiliary_ plexus is formed by the branches of the basilar artery (a. basilaris), which in Latin means “base”, so its other name is the Kodiak-Pahuls plexus. This is the largest formation of the arterial circle of the brain (30th pair), the location of which is in the posterior cranial fossa. In the literature, it is sometimes unfoundedly identified with the _vertebral_ hemisphere, because both structures are located next to each other. The basilar plexus is characterized by alternation with pyramids of nerve fibers and bundles of connective tissue. The anterior part of the plexus is located above the corpus callosum, which prevents the free expansion of the arteries. More medially are the roots of the oculomotor, auditory and trochlear nerves. The posterior part is represented by part of the carotid, nuclei of the vagus, spinal, hypoglossal and trigeminal nerves, as a result of which it is important for the blood supply to the brain stem.