. The comparative anatomy of the domesticated animals. Veterinary anatomy. 682 TEE CENTRAL AXIS OF THE NERVOUS SYSTEM. INTERNAL CONFOEMATION OF THE ISTHBIUS. (Fig. 827.) The encephalic isthmus is hollowed at the thalami optici by a central cavity, named the middle (or third) ventricle, which is extended backwards beneath the corpora quadrigemina by a canal—the aqueduct of Sylvius; this opens, below the valve of Yieussens, into the posterior (or fourth) ven- tricle—another cavity comprised between the cerebellum and medulla oblongata. These three diverticuli will be studied in succession. 1. Mi
. The comparative anatomy of the domesticated animals. Veterinary anatomy. 682 TEE CENTRAL AXIS OF THE NERVOUS SYSTEM. INTERNAL CONFOEMATION OF THE ISTHBIUS. (Fig. 827.) The encephalic isthmus is hollowed at the thalami optici by a central cavity, named the middle (or third) ventricle, which is extended backwards beneath the corpora quadrigemina by a canal—the aqueduct of Sylvius; this opens, below the valve of Yieussens, into the posterior (or fourth) ven- tricle—another cavity comprised between the cerebellum and medulla oblongata. These three diverticuli will be studied in succession. 1. Middle Ventricle, or Ventricle of the Thalami Optici. (Fig. 327, 13.) The middle ventricle is an irregular cavity, elongated from behind to before, depressed on each side, and offering for study two walls, a floor, a roof, and two extremities. The two walls are smooth, nearly plane, or very slightly concave from above to below. The floor is extremely narrow, and only forms a channel whose bottom corresponds to the interpeduncular fissure, which is nearer in front than behind, and to the corpus albicans and tuber cinereum. The cavity of the latter (Fig. 327, 20), prolonged into the pituitary stem, communicates with the middle ventricle, and assists in its formation. The roof, as narrow as the floor, and, like it, nothing but a channel, is constituted by the two thalami optici which are joined to one another above the ventricle, forming a thick Fig. 325. TRANSVERSE SECTION OF THE ENCEPHALON AT THE POSTERIOR COMMON FORAMEN. 1, White substance of the hemisphere, or centrum ovale of Vieussens; 2, 2, Grey substance forming the external layer of the convolutions; 3, Section of the corpus callosum; 4, 4, Interior of the lateral ventricles; 5, Section of the great vena Galeni; 6, 6, Cerebral peduncles; 7, 7, Section of the isthmus; 8, Posterior common foramen ; 9, Posterior white commissure ; 10, Entrance to the aqueduct of Sylvius. grey commissure (Fig. 327, 16). It is terminated at
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectveterinaryanatomy
