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

  • Dean, John, M.D.
Date:
[1864]
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 National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    A moment's reflection suffices to show that by this means a relation is at once established between the nerves of the posterior column of the medulla and the posterior spinal roots, and that the plan in both is precisely similar, although the arrangements of parts may at first sight seem to differ. The analogy between the upper roots of the spinal accessory, vagal and glosso-pharyngeal nerves and the posterior spinal roots seems to be perfect; they traverse the caput cornu, and are connected with cell groups which completely correspond with each other, if not in all respects identical, and this analogy is still further established by the relation they form with the motor roots, as we have already had occasion to notice. Having noticed the relation between the nuclei of the posterior cornua of the spinal cord and those of the medulla, it remains to add a few words with regard to the passage into the medulla of the very interesting columns of longitudinal bundles, which in the cervical region of the cord are shown to be so intimately connected with the tractus intermedio-lateralis. The situation of these bundles in the spinal cord is well seen in the wood-cuts, Figs. 2, 3, 4. In Plate XIII, Fig. 1, ?, the same column is seen, situated close to the entrance of the spinal accessory roots; higher up these bundles are situated just behind the entrance of the roots, and continually increase in size as we ascend (Figs. 3a, 4a, 19, 20a, 21, 22a), till the vagus nucleus has reached its greatest development, from which point upwards they gradually diminish and finally disappear, being replaced by a similar collection of longitudinal fasciculi, which are developed behind these in the substance of the post-pyramidal and posterior portion of the vagus nucleus, and stand in close con- nection with the outer portion of the nucleus of the auditory. The longitudinal columns in connection with the vagus and spinal accessory nuclei have been noticed by Stilling, Schroder van dcr Kolk, and Clarke, and appear from their connection in the medulla with the centres, as well as with the anterior and posterior cornua in the spinal cord, to be intimately concerned in co-ordinating and bringing into harmony the different respiratory movements. The connections of these fasciculi with different parts of the medulla are very striking; as I have shown in various places in the present memoir, they con- stantly penetrate the meshes of a network of cells and fibres, many of these cells being of very considerable size, embracing the bundles with their processes, and in many cases becoming continuous with them, while, on the other hand, some cell processes are sent transversely in all directions, many of them entering the nuclei (vagal and spinal accessory). It is chiefly in this way, I think, that connection is brought about between the roots and the longitudinal columns, for I have not been able to find any direct communication between them, notwithstanding the assertion of Schroder van der Kolk.1 On the outer side of the longitudinal column in the direction of the caput, many cells are found, some of very large size, serving to connect the column with the caput, through the substance of which fibres descend from the trifacial. The opposite columns are brought into commissural connection by means of radiating fibres, some of which join the marginal bundles passing around