Lessons on the anatomy, physiology and hygiene of infancy and childhood for junior students : Consisting of extracts from lectures given at Rush medical college / by Alfred C. Cotton.

  • Cotton, Alfred Cleveland, 1847-1916
Date:
1900
Catalogue details

Licence: Public Domain Mark

Credit: Lessons on the anatomy, physiology and hygiene of infancy and childhood for junior students : Consisting of extracts from lectures given at Rush medical college / by Alfred C. Cotton. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

    106/264 (page 54)
    leaves and twigs of a forest. To these divisions are given the name of dendrons. The older idea of their function was that they were nutritive, but it is now generally believed that they serve as association paths for receiving and trans- mitting varied impulses and are the index] of the ner- vous activity of the individual. In the adult the medullary substance has been estimated as abeut thirty per cent of the entire weight of nerve tissue. Therefore the highest rate of brain development throughout infancy and early child- hood occurs in the medullary portion. In very early infancy the perijjheral nerves have sheaths of myeline, which later may be traced in the spinal cord, medulla oblongata and finally in the cerebrum. The extent of medulation of any tract is an index of the degree of development of that tract. In the same way may be traced the earlier development of those nerve areas which control merely bodily functions and reflexes. The higher intellectual functions show evidence of their activity later, although ultimately they monopolize the greater portion of the cortex. The weight of the spinal cord to body-weight at birth is as 1:500; in adult life, 1:1500. In its longitudinal growth the spinal cord does not keep pace with that of its canal. It is due to this relative shortening of the cord that the roots of the lower spinal nerves assume an increasingly higher rela- tionship to the respective segments from whose foramina they emeige (a point of diagnostic and surgical interest). It will be remembei'ed also in this connection that the tips of the spinous processes vary considerably at different ages in their relations to their respective vertebrae.