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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    At the distal edge of the model the direct cerehellar tract forms a band or ribbon on the surface of the spinal cord (Plate I and Fig. 1.) In approaching the medulla oblongata the fibres converge to form a com{>act bundle (Fig. 28). In this bundle the fibres pass on to a point opposite the distal end of the inferior olivary nucleus where the entire bundle turns dorsahvard at almost a right angle (Fig. 30). The lines in Plate I of the model showing this doi-sal coui*se are perhaps a little too abrupt. They should follow the course of the lines of the transvei*se sections shown on Fig. 52. The fibres extend dorsalward beyond the level of the tractus si>inalis nervi trigemini; here they tuni cerebralward again and join with the dorsal external arcuate fibres to enter the corpus restiforme. This arcuate bundle shows in the model as the direct continuation of the capsule of the nuclei of the dorsal funiculi (Plate I). The line in which the direct cerebellar tract meets this ai-cuate bundle forms an arch, beneath which the tractus spinalis nervi trigemini and its nucleus can be seen. The corjnis restiforme passes cerebral- ward, and at the same time slightly lateralward, to a point op]X)site the level of the nucleus X. abducentis. Here it turns dorsalward to enter the cerebellum and hence is cut off in the model. To return to the cross-section of the spinal cord shown in Fig. 1, all of the medullated fibres of the lateral funiculus have been traced saA'e the ground bundle, for at this stage the lateral pyram- idal tract is non-meduUated. The model shows that the ground bundle of the lateral funiculus has only to ttmi slightly doi*salward, in agreement with the cervical curve in order to enter the fomiatio reticularis of the medulla oblongata. (See the cross-section of the cord in Plate lY). This formatio reticulars region extends throughout the length of the medulla. It lies dorsal to the nucleus olivaris inferior and lateral to the raednlla sbeet. n. FUNK ri.US DORSALIS. The dorsal funiculi of the spinal cord form a wedge-shaped mass as seen in cross-section (Fig. 1). Each funiculus runs to the be- ginning of the medulla oblongata without change of form save that the gToove between the fasciculus gracilis and the fasciculus cune- atns deepens (Plates III and IV). At about the junction of the spinal cord and medulla oblongata, the fasciculus gracilis becomes hollowed out to make a capsule for its nucleus and a little farther