. The comparative anatomy of the domesticated animals. Veterinary anatomy. 676 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. glands: small appended lobes placed one on the superior, the other on the inferior face of the isthmus.^ Fig. 322. Medulla Oblongata. (Figs. 323, 324, 829.) The medulla oblongata constitutes the posterior portion of the encephalic isthmus; it succeeds the spinal cord, and extends forvyard as far as the pons Varolii. It is a thick peduncle of a white colour, wider before than behind, flattened above and below, and having four faces—an inferior, superior, and two lateral. Inferi
. The comparative anatomy of the domesticated animals. Veterinary anatomy. 676 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. glands: small appended lobes placed one on the superior, the other on the inferior face of the isthmus.^ Fig. 322. Medulla Oblongata. (Figs. 323, 324, 829.) The medulla oblongata constitutes the posterior portion of the encephalic isthmus; it succeeds the spinal cord, and extends forvyard as far as the pons Varolii. It is a thick peduncle of a white colour, wider before than behind, flattened above and below, and having four faces—an inferior, superior, and two lateral. Inferior face (Fig. 322).—This face rests in the channel of the basilar process. Convex from side to side, and limited anteriorly by a transverse fissure which separates it from the pons Varolii, posteriorly it does not offer anything to distinguish it from the medullary axis. On the middle line there is a well- marked fissure, a continuation of tlie inferior fissure of the cord, which lies between two very elongated promi- nences that are sometimes but little apparent, and from their form are named ^epyramids of the bulb (corpora pyramidalia) (Figs. 322, 19; 338, 6). The base of these pyramids touches the pons Varolii, and their apex is insensibly lost, posteriorly, on reach- 4, 5, Cerebral hemispheres ; 6, Cerebellum ; ing the Spinal COrd. 7, Optic chiasma, or commissure; 8, Pitui- Oatwardly is an almost plane sur- face, bordered anteriorly by a trans- verse band which lies immediately behind the pons Varolii; sometimes it is covered for the greater part of its extent by a very thin expansion of arciform fibres, between the anterior border of which and the transverse ^ There is far from being any agreement as to the number of parts which ought to compose the encephalic isthmus, some authorities making more, some less. The limits of this small apparatus will, nevertheless, be found perfectly circumscribed if it be ex- amined in the lower animals, and particularly in the Horse. A
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectveterinaryanatomy
