886 
geus) upon the lateral surface of the pharynx. 
(See article Gioss-Puarnynceat Nerve.) 
Superior laryngeal branch (ramus laryngeus 
superior) arises from the inner side of the 
vagus, about four or five lines below the 
superior pharyngeal branch, and from the upper 
and inner part of the second or inferior ganglion. 
It is considerably larger than the pharyngeal 
branch, and in the first. part of its course pro- 
ceeds almost directly inwards, then inwards 
and downwards, passing behind the internal 
carotid and in front of the longus colli muscle.* 
While it is behind the carotid it generally 
divides into its two branches, the internal and 
external, The internal is much the larger and 
more important, crosses the lateral part of the 
middle constrictor of the pharynx obliquely 
downwards, forwards, and inwards, joins itself 
to the Jaryngeal branch of the superior thyroid 
artery and runs along its upper edge, passes 
between the lower margin of the os hyoides 
and upper margin of the thyroid cartilage, and 
reaches the upper edge of the larynx by per- 
forating the thyro-hyoid ligament posterior to 
the external edge of the thyro-hyoid muscle, 
above the upper edge of the inferior constrictor 
and below the lower edge of the middle con- 
strictor of the pharynx, and a little in front of 
the round ligament connecting the superior 
cornu of the thyroid cartilage to the larger 
cornu of the hyoid bone. Sometimes one or 
two small twigs pass between the trunk of the 
vagus and the superior laryngeal soon after the 
origin of the latter, and the external branch 
of the superior laryngeal occasionally comes 
directly from the trunk of the vagus, a little 
below the origin of the internal branch. While 
the superior laryngeal nerve is passing behind 
the internal carotid, it sends off several small 
twigs, some of which communicate with the 
pharyngeal plexus, a few pass downwards and 
throw themselves into some of the cardiac 
nerves, and the greater part run upon the sur- 
face of the internal and external carotids, and 
assist in forming, with the more numerous 
branches from the sympathetic, the- arterial 
plexus of nerves winding round the carotid 
arteries and their branches. 
External branch of the superior laryngeal. 
It is strengthened by some twigs from the 
superior ganglion of the sympathetic, passes 
downwards and forwards over the inferior con- 
strictor muscle of the pharynx and_ lateral 
surface of the larynx, gets below the outer edge 
of the sterno-thyroid, and continues its course 
below it and the thyro-hyoid muscle. It gives 
some twigs to the inferior constrictor muscle, 
some: filaments also to the upper part of the 
sterno-hyoid and thyroid muscles, and to the 
thyroid body. The continuation of the nerve 
after sending a twig downwards to anastomose 
with another twig from the inferior laryngeal 
nerve behind the thyroid body, ultimately ter- 
minates in the crico-thyroid muscle.t 
* The superior laryngeal nerve rarely passes in 
front of the internal carotid. 
+ A small twig from the external branch of the 
superior laryngeal perforates the thyroid cartilage 
occasionally, and anastomoses with some of the 
PAR VAGUM. 
_thyro-arytenoid muscle, and between it and the 
Internal branch of the ior laryngeal. 
Anooon os:this beansh hapipacislenialaiiiaae * 
hyoid ligament and reached the outer surface 
of the mucous membrane immediately beneath 
it, it divides ne Liver branches which 
are flattened an iating, some ing w 
wards and forwards seniede the ios eae 
tongue and sides of the epiglottis, others for- 
wards, downwards, and inwards in the aryteno- 
epiglottidean folds to the surfaces of the epi- 
glottis, and others downwards upon the posterior 
surface of the larynx. The branches which 
proceed forwards and upwards are small and 
pass onwards to the glosso-epiglottidean folds; 
and while some of their filaments terminate in 
these folds and in the mucous membrane at the 
lateral and back part of the tongue, others turn — 
inwards and are distributed upon the sub- 
mucous glands and the mucous covering of — 
the anterior and upper part of the epiglottis. 
Several pretty strong branches forwards — 
and inwards in the aryteno-epiglottidean folds 
to the side of the epiglottis. Some of these 
proceed upon its anterior surface and are there 
distributed upon the mucous membrane and 
the submucous glands, sending also a few — 
filaments through small apertures in the epi- 
glottis to be ramified in the mucous membrane 
on its posterior or laryngeal surface; while 
other branches pass upon the posterior aspect — 
of the epiglottis—some of them ge 
notches on its outer edge,—and are distri 
upon the submucous glands and mucous mem= 
brane covering that surface. A few branches 
proceed downwards and forwards over the outer 
surface of the lining mucous membrane of the 
larynx, send some filaments to the larynge 
sac, and may be traced as far as the inferior or 
true vocal chords. A long slender brane 
passes downwards on the outer surface of th 
inner surface of the thyroid cartilage, and fr 
queutly anastomoses with an ascending b 
of the recurrent or inferior laryngeal. One or 
two slender filaments enter the thyro-aryteno 
muscle, and these, after a long and wind: 
course among the fibres of that muscle 
those of the crico-arytenoideus lateralis, ul 
mately run to the mucous mem of 1 
larynx. A pretty large branch runs backwai 
in the posterior part of the th id fi 
of mucous membrane, transmitting at the sa 
time a few filaments downwards ; and on rea 
ing the arytenoid cartilage it sends eve 
filaments upon the posterior surface of | 
proper arytenoid muscles, and continuing 
course downwards between the mucous ™ 
brane of the pharynx and the crico-arytenol 
posticus muscle, it anastomoses with one 
sterior ascending branches of the recur 
e greater part of the filaments which e 
among the fibres of the arytenoideus po 
and transversus muscles may be traced 
mucous membrane of the larynx, and | 
very few appear to terminate among the mus 
cular fibres; others anastomose with aryteno 
e 
a. 
descending branches of the internal branch of 
Same herve. - 
a 
