. The comparative anatomy of the domesticated animals. Veterinary anatomy. THE CRANIAL OR ENCEPHALIC NERVES. 815 substance which in part closes the occipito-spheno-temporal hiatus, and divides it into several particular foramina. Its superior face is covered by the dura mater, and sends a number of filaments to that membrane. The Gasserian gangUon is not continued by a single trunk, but immediately divides into two thick branches, one of which leaves the cranium by the foramen ovale—an opening formed by the above-named hiatus ; while the other is lodged in the external fissure in the intra-cra
. The comparative anatomy of the domesticated animals. Veterinary anatomy. THE CRANIAL OR ENCEPHALIC NERVES. 815 substance which in part closes the occipito-spheno-temporal hiatus, and divides it into several particular foramina. Its superior face is covered by the dura mater, and sends a number of filaments to that membrane. The Gasserian gangUon is not continued by a single trunk, but immediately divides into two thick branches, one of which leaves the cranium by the foramen ovale—an opening formed by the above-named hiatus ; while the other is lodged in the external fissure in the intra-cranial surface of the sphenoid bone, and passing along it as far as the entrance to the supra-sphenoidal foramina, bifurcates. Hence it results that the trigeminus is divided—even at its origin—into three branches : two superior—the oph- thalmic branch of Willis, and the superior maxillary nerve, commenc- ing by the same trunk ; and an inferior, which constitutes the in- ferior maxillary nerve. Motor or small root (Fig. 426, 8).—This is a flattened band which emerges from the pons Varolii, at the inner side of the principal root. Its fibres may be easily followed to the interior of the pons Varolii (Fig. 451, M'A') ; they disappear in the nucleus of grey substance situated inside the nucleus of the principal sensitive root, near the floor of the fourth ventricle (MA). Leaving the pons Varolii, this root passes forwards on the inferior face of the Gasserian ganglion, which it crosses in a diagonal manner out- wards, and beyond which it inti- mately unites with the fibres of the inferior maxillary nerve. The superior maxillary nerve and the ophthalmic branch do not receive any fibres from it. In the fifth pair, then, it is only the inferior maxillary nerves which are at the same time sensitive and motor, and are real mixed nerves. A, Ophthalmic Branch (or Nerve of Willis) (Fig. 450, 1).—This is the smallest of the three divisions furnished by the Gasserian ganglion ; it
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