SPINAL ACCESSORY NERVE 



513 



SPINAL ACCESSORY (ELEVENTH NERVE) 



The spinal accessory nerve, from the great extent of its origin, its 

 important anastomoses with other nerves and its peculiar course and dis- 

 tribution, has long engaged the atten- 

 tion of anatomists and physiologists, 

 who have advanced many theories in 

 regard to its office. Its physiological 

 history, however, may properly be 

 said to begin with the experiments of 

 Claude Bernard. 



Physiological Anatomy. The ori- 

 gin of this nerve is very extensive. 

 A certain portion arises from the 

 lower half of the bulb, and the rest 

 takes its origin below, from the upper 

 two-thirds of the cervical portion of 

 the spinal cord. That portion of the 

 root which arises from the medulla 

 oblongata is called the bulbar portion, 

 the roots from the cord constituting 

 the spinal portion. Inasmuch as 

 there is a marked difference between 

 the uses of these two portions, the 

 anatomical distinction just mentioned 

 is important. 



The superior roots arise by four 

 or five filaments from the lower half 

 of the medulla oblongata, below the 

 origin of the pneumogastrics. These 

 filaments of origin pass to a gray nu- 

 cleus in the medulla. 



The spinal portion of the nerve 

 arises from the upper part of the 

 spinal cord, between the anterior and 

 posterior roots of the upper four or 

 five cervical nerves. The filaments 

 of origin are six to eight in number. 

 The most inferior of these usually is 

 single, the other filaments frequently being arranged in pairs. These 

 take their origin from the lateral portion of the cord and are con- 

 nected with the anterior cornua of gray matter. 



2 L 



Fig. 124. Spinal accessory nerve 

 (Hirschfeld). 



i, trunk of the facial nerve ; 2, 2, glosso- 

 pharyngeal nerve; 3,3, pneumogastric ; 4, 4, 

 4, trunk of the spinal accessory ; 5, sublingual 

 nerve ; 6, superior cervical ganglion ; 7, 7, 

 anastomosis of the first two cervical nerves; 

 8, carotid branch of the sympathetic ; 9, 10, 

 n, 12, 13, branches of the glosso-pharyngeal ; 

 14, 15, branches of the facial ; 16, otic gan- 

 glion ; 17, auricular branch of the pneumo- 

 gastric ; 18, anastomosing branch from the 

 spinal accessory to the pneumogastric; 19, 

 anastomosis of the first pair of cervical nerves 

 with the^ sublingual ; 20, anastomosis of the 

 spinal accessory with the second pair of cer- 

 vical nerves; 21, pharyngeal plexus; 22, su- 

 perior laryngeal nerve ; 23, external laryngeal 

 nerve; 24, middle cervical ganglion. 



