HELL’s ANATOMY OF THE HUMAN BODY. 
under the hyo-thyroideus, is distributed to. 
the small muscles moving the cartilages. 
The minute extremities of this nérve pass” 
also to the apex of the epiglottis, and the’ 
landular membrane covering’ the glottis. 
Te have, at the same time, to: rémark a: 
very particular communicating nerve betwixt 
this internal laryngeal nerve, andthe recur- 
rent branch of the par vagum, ‘This branch, 
is described by Galen, The par vaguin con- 
tinues its uninterrupted course betwixt the 
carotid artery and jugular vein, and is in- 
volyed in the same sheath with these vessels. 
In this course down the neck, it sometimes 
sénds back a twig which unites with the 
ninth pair, and when near the lower part of 
the neck, it sends forward twigs to unite 
with those from the sympathethic nerve, 
which pass down to the great vessels of the 
heart, to form the superior cardiac plexns, 
On the tight side, these nerves to the great 
yessels are in general given off by the recpr- 
yeRt nerve. | , 
«© "The par vagum now penetrates into the 
thorax by passing before the subclavian ar- 
tery; it then splits into two. The main 
nerve passes on by the side.of the trachea, 
and behind the root of the lungs; while the 
branch, on the right side, turns round 
under the subclavian artery; on the left, 
under the arch of the aorta, and ascends be- 
hind the trachea to the larynx. 
** This ascending branch of the par vagum 
is the recurrent nerve. On’ the right side it 
_ is sometimes double. It ascends behind the 
carotid artery, and sometimes is thrown 
round the root of the thyroid artery. On 
_ the left side, which, frony its turning round 
the arch of the aorta, is. much tower than 
_ on the right, it gives off filaments which go 
_ ta, the lower cardiac plexus, after shaving 
_ united with the branches of. the sympa- 
thetic. Under the subclavian of the right: 
side, also, there are sent branches: from the 
sides there pass branches of communication 
betwixt the sympathetic nerye and she. re- 
ecurrent., When the recurrent. nerye , has 
_ turped round the artery, it aseénds, in a 
 dixection to get behind. the trachea, and it 
lies betwixt.the trachea,and. esophagus. » It 
here sends off many brauches to: the backs 
_ and membranous part of the trachea; which 
; pierce this posterior part, to supply, the in- 
temal membrane.:, It gives also. branches to. 
the,gsophagus and thyroid gland.,.'Phe,tinal 
- distribution ofthis nerve, isito thedarynx. 
it ipierees: betwixt the thyroid. and orisoid 
caztilages, and separates into many filaments, 
which terminate.in. the crico-drytenoideus 
lateralisjand postieusy and thryo-arytenoidens, 
and in the membrane of the larynxs, We 
recurrent to the cardiac plexus ; and on both » 
769 
«Two cases, mentioned by Galen, off 
scrophulous tumours in the neck opened, 
where, the, coasequenge., was loss, of voice, 
have, t2mptecd many, anatomisis , lo, instiiute 
experiments om,the recunent jand )jnternal 
lasyngeal neryes. Notwithstanding the deep, 
situation, of those securreat nerves, Galen- 
Says, they, Were cut ini, these LASCS,, and he 
believed. that +h¢ branch of .communication, 
betyiixt the Jazyngeal and recurrent restored, 
the voice.after.some time had elapsed, Both’ 
the intérnal. laryngeal and «recurrent nerves 
are. necessary to the formation of . the yoice. 
Experiments have been made, upon them in. 
dogs, and. the result is enrious; although, 
the lesser changes of the strength, acuteness,, 
and modulation .of the yoice,could not be, 
well observed in the lower animals. , When, 
the laryngeal nerve is cut, the voice is, feeble, 
but acute; when the. recurrent, nerve is cut,, 
there isa relaxation of those musgles, moving, 
the arytengid cartilages which command the 
opening .of the-gloutis, and in %pnsequence 
the voice is flatter or, graver, or moreraus 
cous.” ine 
<« Thus, we,see that the par yagnm has a 
most appropriate name, and that it 1s/nearly, 
as extensive im. its, connections as the sym-_. 
pathetic itself. It is distubuted,< to,the eso- 
phagus, pharynx, and larynx, to, the thyroid, 
cland,. vessels of, the neck and heart, to, the 
ungs,’ liver, and spleen, .stomach, duodes, 
num, and sometimes to the diaphragm.’ The 
recollection of this distribution will, explain’ 
to us many sypapathies ; for example, , the 
hysterical affection of, the throat when: the - 
stomach is. distended with, flatus, the.exeit- 
ing of vomiting by, tickling the throat, the 
effect which vomiting has, in diminishing the, 
sense of suffocation, that state, of the stomach 
which.is found upon: dissection to. accom- 
pany, hydrophobia,, whether spontaneous, or 
from the-bite of a.dog,”. ..)...,, Yh? 
The second paw is devoted to the’ 
organs of, the, senses, of which the eye 
and the, phenomena .Of,,vision, occupy 
|. (as from their impertanee, they, well.de- 
‘serve'to'do) ta large portion of the vo- 
Jume.!> ‘The’ éar; both of man. and ‘of, 
otheranimals, is alsoconsidered: much. 
rat areas ot patel 
The chaptet on vision-Begihs with a) ° 
eps 44) 1G Delt. PRT 2 Ait : F 
_ short abstract.of the mast essential pro-_ 
positions. in, optics, perhaps rather too 
brief for the .yery,minute, description of 
»parts which follows. 
Weishall,not analyze.this chapter, as 
‘the matter is too,,copious for, condensa-, 
‘tions | A, few, obsepyations, e made 
HtwL iu) ite 
ry 3 Me . eo ~ 
“haye, already mentioned the brauch of,comy.,|,27 panticulardparests Poe flo BS Jr he 
m nication betwixt, the, recurcent and inter-,, favourabletinstangs 9) ythe, ap BOI'S, aCe. 
n at nggal nerves, and, Sabatier describes, ,curacy, ol nemaarke in 9d) $7 auidon tee. 
a bra al the recurrent, which sometimes,., ieetiad bas svia Kee stat rts, 
ascends andijoins the syoppathelic, bightings 7 Deve is a.siucumstauassnthe eperation . 
¢e neck. F of extracting the cataract, which T have se@a + 
Ann. Rey. Vor. If. 3:D 
-! - 
