Manual of general, descriptive, and pathological anatomy (Volume 3).

  • Meckel, J. F. (Johann Friedrich), 1781-1833.
Date:
1832
Catalogue details

Licence: Public Domain Mark

Credit: Manual of general, descriptive, and pathological anatomy (Volume 3). 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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    sacral and lumbar nerves, those of the superior from the first dorsal and the last four cervical; finally, the four superior cervical nerves, which lead by a remarkable transition to the cerebral nerves. Before, describing minutely the nerves of these different regions, we ought to make known the following characters which belong to them in common, and which are important in regard to their topography. 1st. There is no constant difference between the nerves of the right and those of the left sides. 2d. The nerves are not perfectly symmetrical; one is often situated higher than another, and the number of cords is frequently greater by two or three on one side than on the other. But this difference is almost always coiupensatcd for, because then the adjacent pairs vary in the opposite manner. 3d. The upper and lower pairs are much nearer each other than the central. The latter also after the last dorsal nerve, are so near each other that they do not seem like separate nerves. They are also much nearer in the early periods of existence, and even during the first years of life, than at subsequent periods. This propinquity in the superior and inferior regions, is owing to the disproportion between the size of the nerves and the shortness of that part of the spinal marrow from whence they arise. Hence why the smaller thoracic nerves, which arise not much above the place from whence they leave the spinal marrow, are farther from each other, and the reason of the greater distance between the spinal nerves in animals whose necks are longer, and in whom too the spinal marrow descends lower than in man. 4th. The ganglions formed by the posterior roots are situated in the intervertebral foramina, except those of the sacral nerves which are found in the cavity of the sacrum. These ganglions are not all of the same size in all regions, and their development is not in a direct, ratio with that of the nerves. In fact, a ganglion which is usually large, is not unfrequently replaced by another very small, and vice versa. The ganglions of the dorsal nerves are generally the largest, and those of the sacral nerves, especially the last, the smallest. 5th. All the spinal nerves divide soon after coming from the verte- bral column into two branches, an anterior and a posterior, the first of which is often larger than the other, excepting always those of the second cervical nerve, which presents a contrary arrangement. The anterior branches turn first outward, then' forward and inward, and terminate near or upon the anterior median line. The posterior go directly backward, and are distributed to the muscles which fill the groove between the spinous and transverse processes of the vertebras, or in those which correspond to them in the cranium and the skin of this region. The first are distributed to the anterior muscles, which represent these dorsal muscles on the sides and anteriorly, and in those of the extremities.