172 NERVOUS SYSTEM. 



were by no means so satisfactory as tlie single successful ob- 

 servation of Bisclioif. In his memoir on the spinal acces- 

 sory, Bernard gives full credit to Bischoff, and quotes from 

 this author the very words we have just cited. "With regard 

 to the question of priority in the description of the function 

 of this nerve in phonation, there can be no doubt concern- 

 ing the accuracy of the experiment of Bischoff and its correct 

 interpretation, in 1832. He demonstrated that the nerve 

 presiding over the voice is the spinal accessory ; although 

 the fact rested on a single successful experiment, and was 

 not accepted by physiologists before it had been fully con- 

 firmed by the repeated and conclusive experiments of Ber- 

 nard, made by an entirely different method. To Bernard, 

 however, remains, as we shall presently see, the merit of 

 having demonstrated that the vocal muscles are supplied 

 by those filaments of the spinal accessory that take their 

 origin from the medulla oblongata. 



Bernard, whose ingenious experiments determined ex- 

 actly the influence of the spinal accessory over the vocal 

 movements of the larynx, first repeated the experiments 

 of Bischoff; but the animals operated upon died so soon, 

 from hsemorrhage, or other causes, that his observations 

 were not satisfactory. 1 After many unsuccessful trials, he 

 succeeded in overcoming all difficulties, by following the 

 trunk of the nerve back to the jugular foramen, seizing 

 it here with a strong pair of forceps, and drawing it out 

 by the roots. 2 This operation is difficult, but we have sev- 



1 BERNARD, Recherches experimentales sur lesfonctions du nerf spinal, p. 733. 

 Bernard considers that death is due after this operation, as performed by Bis- 

 choff, to the passage of air into the veins. 



8 The operative procedure employed by Bernard is the following: The 

 trunk of the nerve is exposed as it passes through the sterno-cleido-mastoid 

 muscle. It is then followed up by careful dissection, avoiding blood-vessels as 

 much as possible, to the posterior foramen lacerum, when the sublingual is seen 

 crossing the course of the pneumogastric. It is here that the anastomotic 

 branch leaves the spinal accessory to go to the pneumogastric. At this point, 

 the external branch, with the anastomosing branch, is seized with a pair of 

 rather broad-billed forceps, and gentle but firm traction is applied to the entire 



