The _median meningeal artery_ passes through the foramen occupied by the second branch of the trigeminal nerve. Passing into the cranial cavity, it supplies the dura mater. Before passing into this foramen, small branches are given off, which supply the skin and the temporal muscle; and some branches anastomose with the superior cervical and the ethmoidal arteries. =4. The Cerebral Artery.=—Each cerebral artery enters the cranial cavity through the canalis caroticus located in the sphenoid bone, passes forward medially from the cochlea, dorsally from the Eustachian tube, and passes through a small canal which opens on the inner surface of the sella turcica. Originating in this foramen, the _sphenoid artery_ divides into two branches which anastomose with the pterygoidean and the pterygo-pharyngeal artery and which supply the upper jaw and the throat regions. The _spheno-maxillaris artery_ supplies the gums. The right and the left cerebral arteries unite at the sella turcica. After this union they divide again immediately and pass to the base of the brain, where they give off twigs to the optic nerve, to the optic chiasm, and where also is given off the arteria retinæ centralis. Passing posteriorly each cerebral artery gives off the _ramus posterior_, and then passes to the side of the cerebellum. The _basilar artery_, a continuation of the anterior spinal artery, is located ventrally and mesially to the cerebellum. Laterally and inferiorly the basilar artery gives off the inferior cerebellar artery. The _ramus anterior_ is given off from the cerebralis artery and continues as the _internal ophthalmic artery_. The ramus anterior also gives off the _sylvian artery_, which supplies the sides of the cerebrum and the middle brain. In the fissure between the hemispheres and the optic thalamus is located the _arteria cerebri profunda_. This artery passes along the median surface of the cerebrum and in its course supplies the adjacent parts. It enters into the formation of the choroid plexus of the lateral ventricle. The _internal ophthalmic artery_ extends out of the cranial cavity, through the optic foramen, into the orbital cavity. It passes upward along the interorbital wall and supplies the optic nerve, the trigeminus nerve trunk, and the eye muscles, and dorsally anastomoses near the olfactory nerve with the rete ethmoidale and the external ophthalmic artery, and continues as the ethmoidal artery. The _ethmoidal artery_ supplies the supra-orbital gland and the gland of Harder. It gives off twigs to the rete ophthalmicum and other branches to the skin of the frontal region, where it anastomoses with branches of the external facial artery. These branches in the frontal region are rather large. Large branches are given off to the comb. The _arteria ethmoidalis externa_ originates in the nasal cavity from a division of the ethmoidal artery.