SKETCH OF THE NERVOUS SYSTEM. 
631 
pharynx, the larynx, and the oesophagus, it gives large and 
singularly involved plexuses to the heart and the lungs ; and 
having entered the abdomen, its, ramifications on the stomach 
are numerous and complicated. Some plexuses go to the liver; 
and an important branch, uniting with the grand organic nerve 
of the abdomen, helps to form the semilunar ganglion,— an 
organic motor nerve, 
11. Included in the same sheath with the glosso-pharyngeal 
and the cerebro-visceral, is a singular nerve, which anatomists 
have agreed to call the spinal accessory nerve. It is formed by 
the union of several minute filaments derived from the lateral 
column of the spinal chord, some of which may be traced as low 
as the fifth cervical nerve. Having, in the manner I shall here¬ 
after describe, reached the cerebro-visceral and glosso-pharyngeal, 
it neither identifies itself with them, nor communicates with the 
substance of the bfain ; but turns round and escapes in the same 
sheath with those nerves, and, soon separating from them, is 
distributed over some of the muscles of the neck and shoulder, 
associating with them in the involuntary discharge of the 
function of respiration, and therefore being an organic motor 
nerve, 
12, Still posteriorly, on the medulla oblongata, but rising 
from the central column of its inferior surface, we find the Hn- 
guales escaping through the anterior condyloid foramina; running 
between the pterigoideus and the larynx ; penetrating into the 
substance of the tongue, and giving motion to that organ. It 
is a voluntaru motor nerve. 
Here ends our brief catalogue of the cerebral nerves ; but our 
subject would not be complete if I did not glance at the origins 
of the nerves along the course of the spinal chord. At the very 
point where the medulla oblongata terminates in the spinal 
chord, we find the first pair, the suh-occipital, and we may take 
it as a specimen of all the rest. Numerous little filaments arise 
from the longitudinal sulcus between the central and lateral 
columns on the inferior surface of the chord, but which are derived 
from, or may be traced to, the central column; they approximate 
and unite, and form a nervous chord. These, from their kind 
and place of origin, we should suspect to be nerves of voluntary 
motion. Other filaments spring from the corresponding sulcus 
on the superior surface, and may also be traced to the central 
column ; but they are not so numerous, and they are larger and 
bolder in their origin. They also approximate and unite, and 
form a nervous chord; but at the point of union, and still within 
the dura mater, these latter form a ganglion,—a little swelling or 
knot,—immediately beyond which the chord shrinks again to 
