. The comparative anatomy of the domesticated animals. Veterinary anatomy. THE CMANIAL OR ENCEFHALIO NERVES. 721 6. Sixtli Pair (Ahducentes), or External Ocido-motor Nerves. (Kg. 335, 5.) The external oculo-motor originates from the medulla oblongata, imme- diately behind the pons Varolii, by from five to eight converging roots, which appear to issue from between the inferior corpus pyramidale and the lateral fasciculus of the medulla (Figs. 337, 338, h). It is directed immediately forward, leaves the pons Varolii in lying close to the inner side of the superior maxillary nerve, and traverses
. The comparative anatomy of the domesticated animals. Veterinary anatomy. THE CMANIAL OR ENCEFHALIO NERVES. 721 6. Sixtli Pair (Ahducentes), or External Ocido-motor Nerves. (Kg. 335, 5.) The external oculo-motor originates from the medulla oblongata, imme- diately behind the pons Varolii, by from five to eight converging roots, which appear to issue from between the inferior corpus pyramidale and the lateral fasciculus of the medulla (Figs. 337, 338, h). It is directed immediately forward, leaves the pons Varolii in lying close to the inner side of the superior maxillary nerve, and traverses the sphe- noidal canal, which already lodges the ophthalmic branch of the fifth pair and the common oculo-motor nerve, to pierce the bottom of the orbit. It is entirely expended in the external rectus (or abductor) muscle of the eye, after giving off a small ramusoule to the external portion of the posterior rectus. 7. Seventh Pair, or Facial Nerves. (Figs. 110, 336, 337, 338.) The facial (portio diwd) is a nerve exclusively motor at its orgin, but which becomes mixed, during its course, by the addition of several sensitive branches. Origin.—It emanates from the medulla oblongata, immediately behind the pons Varolii, and appears to originate at the external extremity of the transverse band that margins the posterior border of tbat protuberance. But if we attempt to trace its origin in the substance of the medulla oblongata, we see the single fasciculus it constitutes, at its point of emergence, descend into the groove of separation between the pons Varolii and the above-mentioned band ; it then traverses nearly the whole thickness of the medulla, passing between the lateral cord or column, and that portion of the restiform body which is continuous with the large root of the fifth pair. Arrived near the bottom of the fourth ventricle, the facial nerve separates into several roots—some anterior, others posterior—which ^'S- 337- are soon lost in the cells forming i»A2',°'
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