264 ENDOCRINE GLANDS 



characteristic is the extreme smallness of their diameter 

 as compared to those of the animal system. 



More important from a clinical point of view is the 

 grouping of the neurons into functional arcs. 



THE FUNCTIONAL VEGETATIVE MOTOR ARC. 2 



Let us take, if you wish, a motor cell of the vegetative 

 central axis, a vegetative motor cell, situated in one of the 

 medullary segments or one of the middle or posterior 

 lobes. Let us say that this cell is located in the lateral 

 portion of the anterior horn (intermedio-lateral tracts). 

 From this cell will arise an axone, a vegetative fibre with 

 myelin, which reaches the anterior root of a spinal nerve, 

 then follows this nerve up to the sympathetic ganglion of 

 the lateral chain. Leaving then the mixed nerve and 

 following the vegetative fibre, the vegetative ganglion is 

 reached. When this is reached in the simplest case 

 this fibre articulates with a vegetative ganglionic cell. 

 That is, the nerve endings communicate with the ends 

 of the ganglionic cell. From this cell arises a gray ramus, 

 which, leaving the ganglion, goes, either towards a visceral 

 cavity of the organism, or to the periphery, by following 

 again the spinal nerve. In the first case, the visceral 

 nerve reaches the vegetative tissues of the viscera; in the 

 second case, it unites to the spinal nerve to distribute 

 itself to somatic tissues of the periphery, following the 

 distribution of the latter; we must note, however, that 

 certain of these fibres abandon the spinal nerve and its 

 branches, to follow up the spinal nerve, and reach in this 

 way the vegetative tissues of the meninges. This done, 

 we can now classify these fibres and give them a name. 

 First of all let us name the white fibre which joins the 

 vegetative central axial cell, with the ganglionic cell. 



2 For a better understanding of this paragraph see Figs. 20, 22, 23. 



