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 

 FIG. wr.-spinai accessory nerve (Hirechfeid). n i amen t s that take their origin from 



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



geal nerve ; 3, 3, pneumogastrie ; 4, 4, 4, trunk the medulla ODlongata. As it TOinS the 

 of the spinal accessory ; 5, sublingual nerve ; , . . , , ... . , . . 



6. superior cervical ganglion ; 7, 7, anasto- pneumogastric it Subdivides into tWO 

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



rotid branch of the sympathetic; 9,10, 11,12, smaller branches. The first of these 



13, branches of the glosso-pharyngeal; 14, 15, .. ,, -, -, 



branches of the facial ; 16, otic ganglion ; 17, f Orms a portion of the pharyngeal 



auricular branch of the pneumogastric ; 18, , , , , , . m, 



anastomosing branch from the spinal acces- branch of the pneumogastric. I lie S6C- 





ond becomes intimately united with the 

 pneumogastric, lying at its posterior 

 Portion, and furnishes filaments to the 

 inferior, or recurrent laryngeal branch, 

 which is distributed to all of the muscles of the larynx except the crico- 



nerve ; 24, middle cervical ganglion. 



