. The comparative anatomy of the domesticated animals. Horses; Veterinary anatomy. 812 THE NERVES. 3. Third Pair, or Common Oculo-motor Nerves (Figs. 424, 450). The nerves of the third pair emanate from the cerebral peduncles, near the interpeduncular fissure, and at an almost equal distance between the corpus albicans and the pons Varolii, in front of the locm niger. Their roots, seven or eight in each, penetrate the texture of these peduncles, pass backwards, traverse the red nuclei of Stilling, and may be traced to their nucleus, placed above the anterior border of the pons Varolii. This nu
. The comparative anatomy of the domesticated animals. Horses; Veterinary anatomy. 812 THE NERVES. 3. Third Pair, or Common Oculo-motor Nerves (Figs. 424, 450). The nerves of the third pair emanate from the cerebral peduncles, near the interpeduncular fissure, and at an almost equal distance between the corpus albicans and the pons Varolii, in front of the locm niger. Their roots, seven or eight in each, penetrate the texture of these peduncles, pass backwards, traverse the red nuclei of Stilling, and may be traced to their nucleus, placed above the anterior border of the pons Varolii. This nucleus is united, in the middle line, to that of the opposite side. From the union of these roots results a flattened trunk, which is at first carried outward, and is almost immediately inflected forward, to enter—along with the sixth pair and the ophthalmic Fig. 450. branch of the trigeminal nerve—the smallest of the great supra-sphenoidal foramina—the sphenoidal fissure {foramen lacerum basis cranii). The common oculo-motor nerve afterwards arrives, by the orbital hiatus, at the bottom of the ocular sheath, where it separates into several branches destined to the following muscles of the eye : the elevator of the upper eyelid, superior rectus, internal rectus, inferior rectus, posterior rectus—ex- cept its internal fasciculus—and the small oblique. The branch to the latter is remarkable for its great length ; it reaches its destination in passing to the outside of, and then below, the inferior rectus. The motor roots of the ophthalmic gang- lion furnished by this nerve, are given off from the same point as the branch or the small oblique muscle. The nerves of the third pair are purely motor, as is shown by their connections with the inferior plane of the cerebral peduncles, and their exclusive distribution to contractile organs. They excite all the muscles lodged in the ocular sheath, except the external rectus, the great oblique, and posterior rectus. They also inne
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