Diseases of the nervous system / edited by Archibald Church.

Date:
1908
Catalogue details

Licence: In copyright

Credit: Diseases of the nervous system / edited by Archibald Church. Source: Wellcome Collection.

    45/1256 page 17
    of the tapetum coming from the posterior portion of the corpus callosum. The lower horn passes downward and forward close to the tip of the temporal lobe and is covered on the upper side by the tapetum, also by the finer proc- esses of the tail of the nucleus caudatus which here passes into the nucleus amygdalae. The cerebral structures arranged upon the floor of the lower horn are very complicated. Here we find all of the structures with which we have become familiar in the description of the medial surface of the hemispheres, the gyrus hippocampi, the fascia dentata, the fimbria, the marked swelling of the cornu ammonis (pes hippocampi major), and the prominence of the emi- nentia collaterals Meckelii due to the deep entrance from without of the sulcus occipito-temporalis inferior which permits a passage to the posterior horn. The lateral ventricles do not directly communicate with each other but are indirectly united by the foramen Monroi, by the open space on each side between the thalamus opticus and fornix, and also between the lateral ven- tricles and the third ventricle. All of these ventricles are now filled by the plexus chorioidei, profuse vascular twigs covered by an epithelial layer; the latter corresponds to the inserted remains of the medial wall of the hemi- sphere and the roof of the inter-brain. Here we differentiate first a triangu- lar middle leaf, the tela chorioidea ventriculi tertii, which is spread out under the fissura transversa cerebri (Bichat’s furrow) situated under the splenium corporis callosi and the coiumnae fornicis, thence the vascular villi reach the lateral ventricles by way of the foramen Monroi where they chiefly occupy the cella media and the lower horn as the plexus chorioidei lateralis, and then pass to the most anterior point of the latter. The white medullary masses situated below the cortex of the cerebrum of both hemispheres are called the centrum ovale. Among the various projec- tion fiber tracts here included, such as the corona radiata and the association tracts which have been thus far investigated, we shall minutely concern our- selves only with the internal capsule, i. e., that portion of the medulla of the hemispheres formed in thick bundles in which projection fibers are inserted by the lenticular nucleus from without, the caudate nucleus and the optic thalamus from within, a region especially important because here originate the hemorrhages which produce hemiplegia and its sequels. As the tracts are embraced within a narrow space formed by various parts of the cerebral cortex, and their fibers do not interlace, and as. the tracts which pass to the cerebral cortex from the large ganglia, especially from the thalamus opticus, begin to separate and later pass to the corona radiata and the various cortical centers, a comparatively small focus may cause extensive symptoms as to motility, sensation, and the higher spheres of special sense, while these may be definitely localized according to whether such a focus is situated anteriorly or posteriorly. The internal capsule forms an obtuse angle in the genu of which the two crura meet; the anterior, smaller, and physiologically, so far as our knowledge extends, less important crus, the pars frontalis, is situated between the nucleus caudatus and the lenticular nucleus. The posterior, longer crus, which is most frequently affected and which is the usual seat of cere- bral hemiplegia, the pars occipitalis, runs between the thalamus opticus and the lenticular nucleus and extends beyond the latter more occipitally. Hence the entire internal capsule mav be divided into four portions, the ventral, 3
    No text description is available for this image
    No text description is available for this image
    No text description is available for this image