2 92 Mr. Bell on the nerves which associate the muscles 
us. The author therefore entreats attention to the anatomy of 
this nerve, as leading in the most conclusive manner to a 
knowledge of its functions. 
It arises from the cervical portion of the spinal marrow 
(Plate XXXI. fig. I. 4) ; but instead of collecting its branches 
to go out by the side of the vertebrae, like the internal and 
external respiratory nerves, it shoots upwards through the 
theca of the spinal marrow, enters the skull, and joins the 
8th pair of nerves ; from which it has its term of accessory. 
We see the roots of this nerve as far down as the 4th cervical 
nerve.* These roots arise neither from the posterior nor 
the anterior column of the spinal marrow, but betwixt the 
posterior roots of the cervical nerves and the ligamentum den- 
ticulatum, and from the column of medullary matter above 
described. The origins of this nerve come off in one line, 
and that line is in the direction of the roots of the eighth 
pair, and of that nerve which has been proved to be the 
respiratory nerve of the face. In its ascent the accessory 
nerve is attached to the posterior root of the first cervical 
nerve. 
The nerve having ascended through the foramen magnum, 
passes out from the skull associated with the nerves consti- 
tuting the eighth pair , and in the same sheath with them ; 
they all go out through the foramen lacerum, and by the side 
of the jugular vein. In this course the accessory nerve di- 
vides into two. One of these divisions joins filaments of 
the parvagum (Fig. II. 6) ; and these again send nerves to 
the glosso-pharyngeal nerve (Fig. II. 2); and sometimes a 
branch may be seen going to the lingualis medius. The 
* In the ass, its roots are seen to extend much lower down. 
