466 THE RESPIRATORY MECHANISM. 



by the following quotation from Onuf and Collins's article 24 : 

 "According to Gaskell, most of the motor fibers of the rami 

 communicantes are cerebro-spinal; those of the gray rami com- 

 municantes, for the most part, sympathetic. Nothing definite 

 is yet known concerning the mode of origin of the sensory fibers 

 of the sympathetic system nor of the manner of their connec- 

 tion with the cerebro-spinal system. Kolliker claims that all 

 sensory fibers of the sympathetic originate from cells of the 

 spinal ganglia in exactly the same manner as the sensory fibers 

 of the cerebro-spinal system." 



While a study of the vasomotor functions connected with 

 the sympathetic nerves, as portrayed in the literature based 

 on experimental evidence, distinctly indicates that they in- 

 variably transmit efferent impulses, it is evident that some 

 fibers supplied by the ganglia experimentally furnish afferent 

 impulses, such as their identity as hypoglossal nerves would 

 involve, otherwise such authoritative observers as Gaskell and 

 Kolliker could not have referred to them as sensory fibers. 

 That the hypoglossal must be the medullary nerve involved is 

 further shown by the fact, referred to by Foster in the last 

 quotation, that section of the cord below the origin of the 

 phrenic nerve which, as we have just shown, is conjoined with 

 the hypoglossal causes costal respiration to cease. As the 

 hypoglossal, for us, is similar, functionally, to the vagus, the 

 entire active nervous supply of these muscles had thus been 

 interrupted. 



"When the cord is divided just below the medulla all 

 thoracic movements cease, but the respiratory actions of the 

 nostrils and glottis still continue. These, however, disappear 

 when the facial and recurrent laryngeal nerves are divided." 

 The co-ordinative attributes of the larynx are self-evident, 

 since the recurrent laryngeal is a branch of the vagus; but 

 through what agency are they insured in the case of the 

 nostrils? The facial is a general motor nerve which acquires 

 sensory filaments from the vagus and from the fifth pair. 

 Unless we eliminate the levator anguli oris et alae nasi from 

 the co-ordinated structures, filaments from the vagus must 



2 * Onuf and Collins: Loc. cit., p. 13. 



