558 



NERVOUS SYSTEM. 



cord, between the anterior and posterior roots of the upper four or five cervi- 

 cal nerves. The filaments of origin are six to eight in number. The most 

 inferior of these is generally single, the other filaments frequently being 

 arranged in pairs. These take their origin from the lateral portion of the 

 cord and are connected with the anterior cornua of gray matter. 



Following the nerve from its most inferior filament of origin upward, it 

 gradually increases in size by union with its other roots, enters the cranial cav- 

 ity by the foramen magnum, and passes to the jugular foramen, by which it 

 emerges, with the glosso-pharyngeal, the pneumogastric and the internal 

 jugular vein. 



In its course the spinal accessory anastomoses with several nerves. Just 

 as it enters the cranial cavity, it receives filaments of communication from 



the posterior roots of the upper two 

 cervical nerves. These filaments, how- 

 ever, are not constant. It frequently 

 though not constantly sends a few fila- 

 ments to the superior ganglion, or the 

 ganglion of the root of the pneumogas- 

 tric. After it has emerged by the jug- 

 ular foramen it sends a branch of con- 

 siderable size to the pneumogastric, from 

 which nerve it also receives a few fila- 

 ments of communication. In its course 

 it also receives filaments of communica- 

 tion from the anterior branches of the 

 second, third, and fourth cervical 

 nerves. 



In its distribution the spinal acces- 

 sory presents two branches. The inter- 

 nal, or anastomotic branch, passes to 

 the pneumogastric just below the plexi- 

 form enlargement which is sometimes 

 called the ganglion of the trunk of the 

 pneumogastric. This branch is com- 

 posed principally if not entirely of the 

 filaments that take their origin from 

 the medulla oblongata. As it joins the 

 pneumogastric it subdivides into two 

 smaller branches. The first of these 

 forms a portion of the pharyngeal 

 branch of the pneumogastric. The sec- 

 ond becomes intimately united with the 

 pneumogastric, lying at its posterior 

 portion, and furnishes filaments to the 

 inferior, or recurrent laryngeal branch, 

 muscles of the larynx except the crico- 



Fio. 307. Spinal accessory nerve (Hirschfeld). 



1, trunk of the facial nerve ; 2, 2, glosso-pharyn- 

 geal nerve ; 3, 3, pneumogastric ; 4, 4, 4, trunk 

 of the spinal accessory ; 5, sublingual nerve ; 

 6. superior cervical ganglion ; 7. 7, anasto- 

 mosis of the first two cervical nerves ; 8, ca- 

 rotid branch of the sympathetic; 9, 10,41, 12, 

 13, branches of the glosso-pharyngeaj: 14, 15, 

 branches of the facial : 16, otic ganglion ; 17, 

 auricular branch of the pneumogastric ; 18, 

 anastomosing branch from the spinal acces- 

 sory to the pneumogastric ; 19, anastomosis 

 of the first pair of cervical nerves with the 

 sublingual : 20, anastomosis of the spinal ac- 

 cessory with the second pair of cervical 

 nerves ; 21, pharyngeal plexus ; 22, superior 

 laryngeal nerve ; 23, external laryngeal 

 nerve ; 24, middle cervical ganglion. 



which is distributed to all of the 



