on the Structure, Distribution, and Functions of the Nerves. 123 



bine in the motions of the frame in locomotion : the former 

 nerve, however, by its influence renders it a muscle subser- 

 vient to the production of full inspiration. 



3. The spinal accessory nerve is particularly an object in 

 this paper. It is called the superior respiratory nerve of the 

 trunk, and its anatomy demands attention because it leads in 

 a most conclusive manner to a knowledge of its functions. 



It arises from the cervical portion of the spinal marrow; but, 

 different from the two former, which collect their branches to 

 go out by the side of the vertebrae, it shoots upwards within 

 the theca of the spinal marrow, enters the skull through the 

 foramen magnum, and joins the par vaguni; whence it bears 

 the name of accessory : the roots of this nerve are seen issuing 

 from the spinal medulla as low down as the 4th cervical nerve, 

 not from its anterior or posterior column, but from that be- 

 fore mentioned which lies betwixt the posterior roots of the 

 cervical nerves and the ligamcntum denticulatum. Its origins 

 are therefore situated in one line, which is in the direction 

 of the roots of the eighth pair and of the portio dura or respi- 

 ratory nerve of the face. It is attached in its ascent to the 

 posterior root of the first cervical nerve. 



When it has entered the skull, it is associated with the 

 nerves constituting the par vagum, being contained in the same 

 sheath with them; they all go out through the foramen lacerum 

 by the side of the jugular vein. In this course the accessory 

 nerve divides into two branches, one of which joins filaments 

 of the par vagum, and these again send nerves to the glosso- 

 pharyngcal nerve, and sometimes a branch is seen going to 

 the lingualis medius. The more exterior branch descends be- 

 hind the jugular vein, and comes forward and perforates the 

 mastoid muscle, to which it furnishes filaments invariably. 



On escaping from the mastoid muscle, it communicates with 

 a branch of the 3d cervical and receives one from the 2d : it 

 now descends upon the neck and disperses itself to the tra- 

 pezius, by many subdivisions, one of which is increased by a 

 long descending branch of the 2d cervical nerve ; this branch 

 so enlarged passes under the trapezius, attaches itself exclu- 

 sively to the trapezius, and is again joined by branches from 

 the spinal nerves behind the clavicle, where it forms a sort of 

 imperfect plexus, and is finally dispersed among its fibres. 

 Thus do we see that this nerve may with strict propriety be 

 termed the superior respiratory nerve of the trunk ; for it lavishes 

 all its branches on the mastoid and trapezius muscles solely, 

 alter taking a circuitous course to form a junction with the 

 far vagum and with the nerves of the tongue and pharynx; 



Q 2 and 



