The gray substance of the medulla oblongata and trapezium / by John Dean.

  • Dean, John W. (John Wesley), 1938-
Date:
1863
Catalogue details

Licence: Public Domain Mark

Credit: The gray substance of the medulla oblongata and trapezium / by John Dean. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    the anterior part of the nucleus. The restiform and post-pyramidal nuclei are filled with numerous cells, and the latter is closely connected with the vagus nucleus by means of a spur from each, the post-pyramidal body being as it were wedged or dove-tailed into the vagus nucleus. The cells of the caput gradually increase in size and number as we ascend, the caput itself being traversed by the vagus roots. The longitudinal fasciculi in connection with the vagus continually increase in size, and are reinforced by another system of bundles (???) which appear in that portion of the nucleus from which the auditory nucleus is subsequently developed. The lower part of the raphe constituting the olivary commissure contains many cells, rather larger than those of the olivary bodies, and scattered cells are found throughout the entire length of the raphe, as well as in all parts of the anterior and antero-lateral network. At about this height little nuclei are found con- necting the raphe and hypoglossal nuclei with the olivary bodies and antero- lateral nuclei. (5.) Still higher up (Plates T, XIII, 0, 6) the hypoglossal nucleus begins to diminish somewhat in size, its cells being smaller and much less numerous, though a considerable number of large cells are still to be seen as long as the nucleus con- tinues distinct. The cells of the vagus nucleus are very numerous and the roots very distinct. Posteriorly we begin to trace the formation of a new nucleus (7l), in the hinder portion of the vagus, or rather between the vagal and post-pyramidal nuclei. This mass, which is pyramidal in shape, with its longest convex side fitted into the vagus nucleus, its concave side being turned towards, and receiving the post-pyramidal body, becomes the principal nucleus of the auditory nerve. The vagus nucleus is now much diminished in size, and is thrust forwards and wedged in between the newly formed auditory nucleus and that of the hypoglossal. The new mass contains cells of large size, especially at the apex, which projects into the restiform body and into the posterior border of the caput, with both of which it appears to be connected. The restiform and post-pyramidal bodies in this region are thickly studded with large cells, and both the vagal and auditory nuclei are bordered by a network, formed by the passage of numerous longitudinal fasciculi, which continue to increase both in size and number as we ascend (Fig. 6ffl, ?, mi). The caput cornu through which the large roots of the vagus pass, is thickly studded with cells of medium size. The antero-lateral nucleus is still quite conspicuous, but the cells are separated into more distinct groups, intersected in every direction by the arciform and transverse fibres. Cells are also scattered in the network by which the entire edge of the caput is surrounded, embracing with their processes the large bundles of longitudinal fibres which traverse it. The olivary bodies have now obtained their maximum development, and soon begin to diminish in size with the diminution of the hypoglossal nucleus and roots (Figs. 6, 7a, 0). In the upper portions of the medulla the remains of the olivary lamina seem to be filled with larger cells, which have replaced the small regular cells of the lower portions. They still extend across the raphe through the commissure. (6.) In the section just above the preceding (Plates I, XIII, Figs. 7, 7) the hypoglossal nucleus, though still large, contains but few cells, and these very much