Lessons in elementary physiology / by Thomas H. Huxley.

  • Huxley, Thomas Henry, 1825-1895.
Date:
1915
Catalogue details

Licence: Public Domain Mark

Credit: Lessons in elementary physiology / by Thomas H. Huxley. Source: Wellcome Collection.

    564/642 (page 534)
    When this tract is traced forwards above the bulb it is found to pass into the crus cerebri of its own side and to pass along the lower or ventral part of the crus, which is known as the pes. The optic thalami and corpora striata are, as we have seen (p. 508), deposits on the course of the crura as the latter sweep forward into the hemispheres. Now when the fibres of the pyramidal tract reach the level of the thalamus they rise up out of the crus, and, spread¬ ing like a fan, pass posteriorly between the optic thalamus and the hinder end of the corpus striatum, and anteriorly between the two parts of which the front end of the corpus striatum is composed. The fibres of the pyramidal tract as they thus pass between the optic thalamus and corpus striatum are known as the internal capsule, and the bend the fibres make as they rise out of the crus is known as its “knee.” From this point onwards the fibres pass directly to their.connections with the cells in the grey matter of the cortex along the region of the fissure of Rolando. The preceding Figure 172 shows diagrammatic- ally the course of the pyramidal tract from the cerebral cortex to the spinal cord.