ecurrent; and, 7, to the aryteno-epiglottic 
ucous folds and muscles. 
The inferior laryngeal or recurrent nerve 
es filaments, 1, to the pneumo-gastric and 
diac plexus; 2, to the pharynx; 3, to the 
achea ; 4, to the esophagus; 5, to the crico- 
ytenoideus posticus; 6, to the arytenoideus 
liquus and transversus; 7, to the crico- 
jtenoideus lateralis and thyro-arytenoideus ; 
an anastomosing branch to the superior 
Our knowledge of the anatomical distribu- 
1 of the laryngeal nerves, and of the func- 
is of the intrinsic muscles of the larynx, 
sufficient, independently of experiment, to 
onstrate the inaccuracy of the well known 
n of M. Magendie, supported by Clo- 
Pinel, Percy, and several others, that the 
urrent nerve presides over those actions 
th open the glottis, whilst the superior la- 
geal influences those muscles which close 
glottis. The principal facts opposed to 
rt y of M. Magendie may be briefly 
ed as follows. 1. It was well known long 
re the promulgation of Magendie’s views 
the inferior laryngeal nerve gave to the 
muscle a filament which had been 
sribed by Andersch,* Bichat,t and Mec- 
and subsequently by Schlemm Bischoff, 
, Cruveilhier, Dr. Reid, and others, there- 
it has been sufficiently demonstrated that 
he recurrent nerve supplies the muscles that 
se, as well as those which open the glottis. 
-M. Magendie has stated that the crico- 
ytenoideus lateralis and thyro-arytenoideus 
yened the glottis, whereas in the preceding 
fails it has been proved that these muscles 
€ it. 3. The loss of voice which follows 
section of the recurrent nerves results from 
walysis of all the muscles (except the 
co-thyroid) which both open and close the 
a fact proved by the experiments of 
lois and Dr. Reid. The limited space 
d to this article will only permit us to 
the conclusions to which recent expe- 
s have arrived respecting the functions 
laryngeal nerves. ‘The external branch 
superior laryngeal is composed chiefly 
motor fibres, and it controls the action of 
2 crico-thyroid and the other muscles to 
ich it gives filaments. The internal branch 
the superior laryngeal is composed of sensi- 
ive fibres, which confer the most exquisite 
sibility on the mucous membrane of the 
yNx, more especially in its supra-glottideal 
ion. It is therefore the sensitive and the 
itor nerve of the larynx. The inferior la- 
geal supplies the muscles that hoth open 
| close the glottis, and is chiefly a nerve of 
Motion when it reaches the larynx, but a few 
if its fibres go to the mucous membrane. The 
mion of the superior with the inferior laryngeal 
ranch by an anastomosing filament, preserves 
-Teciprocal play in the functions of these 
; 
— theo 
b 
* 
enolc 
Fragmentum descr. nervor. 
+ Traité d’Anat. tom. iii, p. 216. 
¢ Man. d’Anat. tom. iii. p. 66, 
NORMAL ANATOMY OF THE LARYNX. 
113 
nerves: whilst the branches anastomosing with 
the sympathetic, connect the larynx with the 
ganglionic system ; the pulmonary and cardiac 
branches connect it with the respiratory and 
circulating systems, and thus associate the 
larynx with those vital functions. The laryn- 
geal nerves also belonging to the reflex system, 
Impressions made on the sensitive filaments of 
the larynx are reflected to the medulla ob- 
longata, and propagated. by a circuitous route 
to the motor filaments of the recurrent, so that 
a long interval is traversed in circulating an 
impression from the sensitive to the motor 
nerves of the larynx; but according to the esti- 
mate made of the speed with which an impulse 
is propagated along a nerve, which is assumed 
to be equal to that of electricity, the time occu- 
pied to transmit an impression from the fila- 
ments of sensation to,those of motion must be 
inappreciable to our senses. Other important 
physiological considerations result from recent 
experimental researches, those of Le Gallois 
and Dr. Reid in particular. 1. With respect 
to the motions of the glottis during respiration, 
the dilatation during inspiration, and contrac- 
tion during expiration, are the effects of the 
play of muscular force in opposition to the 
direction of the current of air in its passage 
to and from the lungs, the tendency of which is 
to produce the reverse action.* There is a 
constant periodical oscillatory motion of the 
arytenoid cartilages, revolving upon the axis of 
articulation, O P, (fig. 30,) at every expiration 
and inspiration ; hence the necessity of a syno- 
vial membrane to lubricate the crico-arytenoid 
articulation. 2. When the recurrent nerves 
are diseased, compressed, or cut, so as to para- 
lyse the crico-arytenoideus.posticus, the power 
of muscular action in opposition to the direction 
of the inspired air is lost. The valves of the 
glottis are drawn downwards with the air, the 
anterior apophysis of the arytenoid cartilages 
rotated inwards, the chink closes, symptoms of 
suffocation supervene, and asphyxia results. 
When spasmodic closure of the chink of the 
glottis occurs, the obstacle to the ingress of air 
is increased by convulsive attempts to draw in 
the breath, which causes a rarefaction of the 
air below the glottis, and augments the atmos- 
pheric pressure above it; and the chest thus, 
says Dr. Ley, ‘* becomes hermetically sealed.” 
If the aperture of the glottis be partially open, 
the air rushing through it causes a stridulous 
sound (/aryngismus stridulus ), whilst in ano- 
ther position of the glottis the crowing inspi- 
ration is produced ; this effect arises (accord- 
ing to Dr. Ley) from the chink of the glottis 
being partially open for the admission of air, 
and remaining so until an explosive expiration, 
such as screaming, coughing, or belching, me~ 
chanically bursts open the floodgates, and 
terminates the paroxysm. 
* In the production of these periodical mover 
ments, the action of the muscles is involuntary, but 
in their action for the purposes of voice, they be- 
come subordinate to the will, and therefore belong 
also to the voluntary system. 
I 
