Page:Structure and functions of the body; a hand-book of anatomy and physiology for nurses and others desiring a practical knowledge of the subject (IA structurefunctio00fiskrich).pdf/83

 the brain. At the base of the brain are also the exits of the twelve cranial nerves.

—Base of brain. (Leidy.) 1, 2, 3, cerebrum; 4 and 5, longitudinal fissure; 6, fissure of Sylvius; 7, anterior perforated spaces; 8, infundibulum; 9, corpora albicantia; 10, posterior perforated space; 11, crura cerebri; 12, pons Varolii; 13, junction of spinal cord and medulla oblongata; 14, anterior pyramid; 14^x, decussation of anterior pyramid; 15, olivary body; 16, restiform body; 17, cerebellum; 19, crura cerebelli; 21, olfactory sulcus; 22, olfactory tract; 23, olfactory bulbs; 24, optic commissure; 25, motor oculi nerve; 26, patheticus nerve; 27, trigeminus nerve; 28, abducens nerve; 29, facial nerve; 30, auditory nerve; 31, glossopharyngeal nerve; 32, pneumogastric nerve; 33, spinal accessory nerve; 34, hypoglossal nerve.

Upon entering the brain the arteries run a tortuous course, the tortuosity breaking the force of the blood stream in the small vessels where congestion would be with difficulty relieved. The basilar artery, which is formed by the juncture of the two vertebrals, divides into the two posterior cerebrals, each of which joins one