An atlas of the medulla and midbrain / Edited by H.McE.K.

  • Florence R. Sabin
Date:
1901
Catalogue details

Licence: In copyright

Credit: An atlas of the medulla and midbrain / Edited by H.McE.K. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    trough i« cut in iToss-section and its fil)res can be traced to a point just ventral lo the central canal. A single section will suffice to show the relations of the fasciculus long-itudinalis medialis in the pons. In the nii<il)rain the 1rouf>-h described before in connection with this bundle is seen in Figs. 4(') to 51. Its shape, its relations to the nucleus .V. oculo- niotorii and the nucleus X. trochlearis, and especially the superior con- nections of its walls deserve notice. In the last section, Fig. 51, the rela- tion to the nucleus of Darkschewitsch is evident. These connections will be considered in detail in the study of the midbrain. The longitudinal series, as in the case of the lemniscus medialis, gives the best idea of the medial longitudinal bundle (Figs. 7 to 20). A view of the model from the lateral aspect shows that this bundle reaches its most dorsal point opposite the nucleus N. abducentis (Plate VI). The section in Fig. 7 passes through this point. Fig. 9 gives the best view of the bundle, both as to its shape and its relations. The two extremities of the bundle in this section represent the positions of Ihe cervical and midbrain curves. By tracing the series ventralward the following points can be studied: (]) the ventral course of the fibres at either end, (2) the widening of the bundle at the proximal end, (3) the formation of the midbrain trough, (4) the relation of the latter to the nuclei of the oculomotor and troch- lear nerves, and (5) the relation to the nucleus of Darkschewitsch, the posterior commissure-and the capsule of the red nucleus. Since the medial long-itudinal bundle is especially related to a grou]) (if cerebral nerves, it may be well to consider these relations in detail. In the model there are four depressions in the bundle, one in the medulla oblongata, one in the pons, and two in the mid- brain. These four depressions correspond to the nuclei of (1) the Is. hypoglossus, (2) the N. abduceus, (3) the N. trochlearis and (4) the X. oeulomotorius. The nucleus X. hy^joglossi corresponds to the shallow depression just proximal to the distal dorsal angle of the medTdla sheet (Plate VI and Fig. 31). The nucleus is a long- one and lies in the gray matter ventral to the central canal. The nucleus of the X. abducens lies in this same central gray matter close to the floor of the ventricle (Plate VI). It lies farther lateral than any other nucleus of this group, as though it had been pulled from the middle line by the knee of the root of the facial nerve (Plate II). The fibres of the root of the N. abducens pass through the edge of the medial longitudinal btmdle. The relations of the nucleus X. abducentis arc shown in Fig. 7. In the midbrain trough of the medial longitudinal bundle are embedded the nuclei of the oculomotor and trochlear nerves (Plate VII). Since the nucleus X. trochlearis is asymmetrical, there are two deju'essions in the fa.sciculus longitudinalis medialis on the right side and one
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