CHAPTER YI. 



SPINAL ACCESSORY AND SUBLINGTJAL NERVES. 



Spinal accessory nerve (third division of the eighth) Physiological anatomy- 

 Properties and functions of the spinal accessory Functions of the internal 

 branch from the spinal accessory to the pneumogastric Influence of the 

 spinal accessory over the vocal movements of the larynx Influence of the 

 internal branch of the spinal accessory upon deglutition Influence of the 

 spinal accessory upon the heart Functions of the external, or muscular 

 branch of the spinal accessory Sublingual, or hypoglossal nerve (ninth) 

 Physiological anatomy Properties and functions of the sublingual Glos- 

 so-labial paralysis. 



A DESCRIPTION of the properties and functions of the spi- 

 nal accessory and the sublingual completes the physiological 

 history of the motor nerves emerging from the cranial cav- 

 ity. The functions of these nerves are important, and, in 

 the case of the spinal accessory, possess considerable inter- 

 est, from the fact that physiological investigations have, only 

 within a few years, determined the significance of certain of 

 its anatomical relations. As we have done in studying the 

 other motor nerves, we will treat successively of their ana- 

 tomical relations, general properties and functions. 



Spinal Accessory Nerve. (Third Division of the Eighth.) 

 The spinal accessory nerve, from the remarkable extent 

 of its origin, its important anastomoses with other nerves, 

 and its curious course and distribution, has long engaged 

 the attention of anatomists and physiologists, who have ad- 

 vanced many theories with regard to its office. We will 

 content ourselves, however, with a simple description of its 



