. The anatomy of the human body. Human anatomy; Anatomy. 822 Pig- 296. fifth nerve comes from the back part of the medulla ob- longata, from the interior of its fasciculi of re-enforce- ment {faisceaux innomines).* As to the small root, it cannot be traced beyond the surface of the Cranial Course.—After emerging from the pons, the fifth nerve passes upvi'ard, outward, and forward, under the form of a flattened bundle, gains the upper border of the petrous portion of the temporal bone {5, Jig- 296), on which there is a depression that is converted into a canal for the nerve b
. The anatomy of the human body. Human anatomy; Anatomy. 822 Pig- 296. fifth nerve comes from the back part of the medulla ob- longata, from the interior of its fasciculi of re-enforce- ment {faisceaux innomines).* As to the small root, it cannot be traced beyond the surface of the Cranial Course.—After emerging from the pons, the fifth nerve passes upvi'ard, outward, and forward, under the form of a flattened bundle, gains the upper border of the petrous portion of the temporal bone {5, Jig- 296), on which there is a depression that is converted into a canal for the nerve by a fold of the dura mater; the nerve is reflected upon this border, and proceeds as will presently be described. The Central Extremity of the External Motor Jferve of the Eye. The external motor jierves of the eye (6, figs. 276, 295), external oculo-muscular nerves, nervi abducentes, or the sixth pair, which are distributed exclusively to the external rectus or abductor muscle of each eye, and which are so re- markable for their communications with the sympathetic system, are smaller than aU the cranial nerves, excepting the pathetic. Apparent Origin.—The statements of authors regarding the apparent origin of this nerve have been singularly various : some, with Morgagni, describe it as arising both from the pons and the anterior pyramids ; others, with Vieussens, from the pons alone ; and others, with Lieutaud, from the anterior pyramids only. Winslow states that it arises between the pons Varohi and the olivary body, and Haller, that it proceeds from the furrow be- tween the anterior pyramid and the pons. The fact is that this nerve, among some varieties of origin, presents two very distinct roots (see fig. 276): one internal and smaller, which arises from the pons, either at or near its lower border; the other external and larger, which appears to emerge on the outer side of the upper part of the anterior pyramid. These two roots are fasciculated : not unfrequently some
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