1TO NERVOUS SYSTEM. 



the medulla oblongata are distributed to the muscles of the 

 pharynx and larynx, while the filaments from the spinal cord 

 go to the sterno-cleido-mastoid and trapezius. 



The trunk of the spinal accessory, after the nerve has 

 passed out of the cranial cavity, is endowed with a certain 

 degree of sensibility. If the nerve be divided, the periph- 

 eral extremity manifests the recurrent sensibility, but the 

 central end is also sensible, probably from direct filaments 

 of communication from the cervical nerves and the pneumo- 

 gastric. As we have remarked, however, in treating of the 

 properties of some other of the cranial nerves, it is exceed- 

 ingly difficult to note satisfactorily a slight degree of sensi- 

 bility in nerves that can be exposed only by a tedious and 

 painful operation. 



The functions of the external, or muscular branch of the 

 spinal accessory are sufficiently evident ; and the effects of 

 the destruction of the nerves on both sides, as far as this 

 branch is concerned, simply resolve themselves into the 

 phenomena due to partial paralysis of the sterno-mastoid 

 and trapezius ; but the functions of the branch which joins 

 the pneumogastric are much more complex. Without dis- 

 cussing the speculative views of the older anatomists and 

 physiologists, we will commence with the experiments of 

 Bischoff, which were the first to give us any definite ideas 

 of the functions of the internal branch. 



Functions of the Internal Branch from the Spinal Acces- 

 sory to the Pneumogastric. Bischoff attempted to ascertain 

 the functions of this branch by dividing the roots of the 

 spinal accessory on both sides in a living animal. The re- 

 sults of his experiments may be stated in a very few words. 

 He attempted to divide all of the roots of the nerves on 

 both sides by dissecting down to the occipito-atloid space 

 and penetrating into the cavity of the spinal canal. In the 

 first three experiments on dogs, the animals died so soon 

 after section of the nerves, that no satisfactory results were 



