. Elements of physiological psychology; a treatise of the activities and nature of the mind, from the physical and experimental points of view . between the ventricleand the uppermost pontine fibres. sembling the bulb, the bundles of which are indeed continued up-ward here. This dorsal part of the pons is called the hood ortegmentum; and the ventral part is called the foot. § 18. A section somewhat farther forward cuts the mid-brain atthe level of the posterior quadrigemina (compare Fig. 38). Thefillets, medial and lateral, are visible above the foot; and the lateralfillet is seen to have move
. Elements of physiological psychology; a treatise of the activities and nature of the mind, from the physical and experimental points of view . between the ventricleand the uppermost pontine fibres. sembling the bulb, the bundles of which are indeed continued up-ward here. This dorsal part of the pons is called the hood ortegmentum; and the ventral part is called the foot. § 18. A section somewhat farther forward cuts the mid-brain atthe level of the posterior quadrigemina (compare Fig. 38). Thefillets, medial and lateral, are visible above the foot; and the lateralfillet is seen to have moved dorsally, its fibres passing to the posteriorquadrigeminum, which is a centre for hearing. The abundantdecussating fibres above the fillet are from the superior pedunclesof the cerebellum. The third ventricle has now narrowed to theaqueduct, which is surrounded by gray matter, containing thenuclei of the third and fourth nerves, which are motor to the eyemuscles. § 19. A section through the anterior quadrigemina (Fig. 39) maystrike also the hind part of the inter-brain, which overlaps the mid- 84 GROSS STRUCTURE OF THE NERVOUS SYSTEM. Fig. 38.—Cross-section of the Mid-Brain at tlie Level of the Posterior Quadrigemina. (Mar-burg.) In place of the fourth ventricle we have here the narrow Aqueduct, Aq. Abovethis, on each side, lie the posterior quadrigemina, Qp. The aqueduct is immediatelysurrounded by gray matter, below which is Flm, the median longitudinal bundle. Belowthis is a large mass of decussating fibres, D, from the superior cerebellar peduncles; belowand to the side of this is the fillet, Lm; and above this, near the quadrigeminum, thelateral fillet, lA. So much for the tegmentum; the foot still shows the interweaving ofpontine and pyramidal fibres. Gray matter of the AqueductAqueduct Redmideut
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