OF THE FACIAL NERVE. 233 



We shall now find that the eighth pan-, that is to say, the nei'ms vagus and plosso- 

 pharyngeus, is situated so as to draw roots from the sensitive column. 



By such a mode of dissection, it will be found that the facialis or jwrtio dura 

 of the seventh nerve has dh-ect connection with the motor and respu-atory columns, 

 and hardly less directly is related to the fourth and sixth nerves. 



The facial nerve, thus arising, allies itself with the auditory nerve, and passes 

 into the temporal bone. In its passage through that bone, it exchanges fibres 

 with the branches of the fifth nerve, and after some intricacies, escapes by the 

 stylo-mastoid foramen, to expand upon the cheek, and finally to reach every 

 pai-t on the side of the head, with the exception of the muscles of the jaws. Al- 

 though its connection on the side of the neck countenances the view I am about 

 to give of this nerve, yet we must draw our inferences chiefly from the origin and 

 functions of the nerve. 



0/the Function of the Facial Nerve, or Pm'tio Dura. 



In the facial nerve we have an organ of most complex operation. It com- 

 bines the passages with the great internal organ of respiration. It animates the 

 lips and cheeks in combination with the organs, so as to give both speech and 

 expression. It is the source of aU the sympathetic actions which illuminate the 

 features in unison with the condition of the mind. It has some remarkable effects 

 on the eyes, which subject we shaU resei-ve to be taken apart fi-om the present 

 inquiry. 



That the facial nerve is the respiratory nerve, I early shewed, by dividing it 

 in brutes ; when, although sensibility remained, all action in the face was cut off, 

 excepting the motion of eating. Many occurrences in the practice of my profes- 

 sion have exhibited the same results from the same cause in man. 



Though one of the most celebrated philosophers of oiu- day, Dr Young, asked 

 rather querulously, " What had the face to do with respiration ?" yet must it be 

 obvious (unless, indeed, the mind be exclusively engaged in observing the chemi- 

 cal phenomena of the economy), that the tubes which give passage to the air, 

 being soft and phant, and subject to the pressure of the atmosphere, must be 

 dilated, and their sides held apart by muscular action. How also are they to ad- 

 mit of breathing, and more especially, how is the expansion of the tubes to be 

 adapted to the excited condition of breathing ? I have ah-eady alluded to the ster^ 

 tor consequent on the relaxation of the tubes in apoplexy. And when this nerve 

 is deprived of power, we find the relaxed lips playing in the act of breathing like 

 the flapping of a sail. 



It will not therefore be again asked, why a branch of that system of nerves 

 which animates the organs of respiration extends to the lips and nostrils, as other 

 branches tend to the velum palati, the throat and larynx. 



VOL. XIV. PART I. Gg 



