=The Abducens= (Fig. 62, No. _C_, 13).—This nerve originates in the somatic and motoric column along with the other nerves of the eye muscles. Its nucleus lies in the circle of the pars commissuralis of the cerebellum. The nerve then passes ventrally, as does the motoris oculi and leaves the brain along the median line. This is a comparatively large nerve and passes somewhat laterally and ventrally from the foramen opticum through a canal in the sphenoid. It then enters the orbital cavity. Some muscular twigs are given off to the quadratus and to the pyramidalis muscle. This nerve also innervates the external rectus muscle of the eye. The abducens anastomoses with the ramus ciliaris and the ophthalmic nerve and gives fine nerve twigs to the ramus ciliaris externus of the ciliary ganglion. =The Facialis and the Acusticus.=—The facial nerve originates with the auditory (Fig. 62, No. _C_, 14 and 15) in a very vaguely known manner, from the cerebellum. It divides into three parts. The first of these probably comes from the complex ganglion with the posterior roots of the auditory. This part belongs to the somatic sensory group of nerves. From this same group originates the auditory, which spreads out into the cochlea and takes the impressions of sound. This nerve is short and thick, and, at the point where it loses its medullary covering on entering the cochlea, there is developed a ganglion. This ganglion is similar to the spinal ganglia. The second part is provided with one root which originates mesially and ventrally, from the deeper ganglion cells. Some of the fibers from this root constitute the vestibular branches. They accompany the auditory and supply the anterior part of the ear labyrinth and the semicircular canals. The larger part of the fibers of this trunk make up the intermediate part of the facial. The geniculate ganglion is formed at their fusion. The sympathetic spheno-palatine nerve emerges from this ganglion, coming out of the aqueduct of Fallopius. The third part, called the portio dura, is the main facialis. It is located opposite the auditoria intermedia. Its roots may be traced to the complex ganglion, from which they take a direction ventrally from the median portion.