NECK. 
___ the nervus vagus lies deeply between the two 
| vessels and behind them; the cellular mem- 
brane, which invests and binds them together, 
4 appears to form an indistinct septum to isolate 
the artery; crossing the front of the sheath,— 
from the median line toward the jugular trunk, 
eon which they pierce—are many veins, 
of which some are occasionally considerable in 
size: they are branches from the larynx, trachea, 
thyroid body, and sub-hyoid muscles, and 
among them, when it exists, must be counted 
the anterior jugular: they are capable of caus- 
ing much inconvenience to the operator, and 
uire to be carefully managed: on the left 
side, the internal jugular vein itself, inclining 
__ toward the median line below, slightly overlaps 
_ the artery: the posterior layer of the sheath of 
these vessels is a thin process of the fascia in- 
terposed between them and the sympathetic 
nerve, which descends vertically behind: se- 
parated in like manner from the great vessels, 
_ we find the inferior thyroid artery, which as- 
ends in an obliquely serpentine course to the 
lower angle of the thyroid body, and the recur- 
rent laryngeal nerve, mounting (on a plane 
_ deeper than that artery, internal to which it is 
Situated) toward the posterior part of the cri- 
_ coid cartilage; the nerve is therefore very nearly 
approached to the hindermost part of the tra- 
ot cartilages, and, on the left side, ascends 
_ between them and the cesophagus, closely ap- 
 Plied to the latter.* 
__* The cardiac branches of the sympathetic,—although 
they require notice in connexion with the anatomy 
‘of the large vessels,—have little particular interest 
‘in regard of the surgical operations, which are prac- 
4 a on these, and some account of them is there- 
_ fore better appended in a note than blended with 
_ the text. They are seldom or never distinctly seen 
_ im operations; and the rule for their management 
is bat a part of the general principle (which ought 
_ to be supreme in every surgical exposure of an ar- 
_ tery, and the neglect of which has been, I doubt 
“not, at the root of most unsuccessful issues) that 
the disturbance of surrounding parts, and the de- 
nudation of the artery, should both be in the very 
least degree, which will permit the ligature of the 
vessel to be accomplished. The cervical cord of 
the sympathetic lies, as already mentioned, behind 
the sheath of the cervical vessels, and presents 
e ganglia, from which, and from the cord, va- 
rious branches originate. Of these ganglia,—the 
uppermost has often above an inch in length, is of 
_tapering rounded form, and is situated in the pos- 
terior pharyngeal region, on the second and third 
vertebrz : the second, of smaller size and incon- 
stant occurrence, usually lies upon the inferior thy- 
roid artery: the third, frequently confused with 
the first dorsal ganglion, is deeply imbedded behind 
the origin of the vertebral artery. From these 
sources, assisted and reinforced by the pneumo- 
gastric and other nerves, the cardiac branches ori- 
gimate in a manner and succession which will be 
described in a future article. (See SYMPATHETIC 
NERVE.) In descending, they lie posterior to the 
sheath, and the superior one internally to it, close 
to the trachea, and, on the left side, to the cso- 
phagus. When they approach the inlet of the 
thorax, they comport themselves variously in regard 
of the subclavian artery; sometimes passing behind 
it, on each side, and furnishing twigs, which cross 
its anterior surface ; sometimes, on the contrary, 
crossing its front by their main branches; and some- 
times so dividing as to envelop the artery in an 
abundant nervous plexus. They are very irregular ; 
575 
The thyroid body belongs to this space by its 
lateral parts, and, when of moderate develop- 
ment, overlaps the carotid sheathy It consists 
of symmetrical Jobular halves, united by the 
isthmus already alluded to: its lobes are pear- 
shaped, on a section, the small end being up- 
ward ; they are plump outwardly where the 
fascia gives them a smooth envelope, but hol- 
lowed inwardly where they adapt themselves 
to the air-tube: the isthmus commonly con- 
nects the lobes by their lower part only, by over- 
bridging the trachea at about its second and 
third rings; the apex of each lobe reaches to 
the ala of the thyroid cartilage, covering the 
fibres of the constrictor pharyngis, which arise 
there, and receiving the superior thyroid artery 
from the external carotid : the circumference of 
the organ presents, then, upward a crescentic 
sinus in which the angle of the thyroid 
cartilage, the crico-thyroid membrane and 
muscles, the cricoid cartilage, the first one, 
two or three rings of the trachea are 
seen: its thick outer margin,—running from 
the apex to the third, fourth, or fifth 
ring of the trachea—corresponds in that extent 
to the carotid artery, which it more or less 
overhangs, and below to the recurrent nerve of 
the larynx; by the extremity of this border the 
inferior artery reaches it from the thyroid axis ; 
the inferior margin gives exit to veins, which 
have already been mentioned, and not infre- 
quently receives by its middle a fifth artery 
from the arch of the aorta or from the arteria 
innominata. 
From the remarkable vascularity of this 
body, so disproportionate to its volume and 
apparent unimportance in the ceconomy, it 
readily falls into the heterogeneous group which 
the German anatomists have named “ Blood- 
ganglia” ( blut-knoten ). Fiom thesame circum- 
stance, and from the probably vicarious func- 
tion which it seems to discharge, it is extremely 
lfable to hypertrophy, the different forms of 
which, attended by whatever structural change, 
are confounded under the name of goétre or 
bronchocele. From the account given of its 
anatomy, the symptoms of its enlargement may 
be surmised; for it is obvious that a tumour, 
so related to the windpipe and so checked in 
its outward growth by tense aponeuroses, must 
gravely affect respiration. Overlapping the 
common carotid arteries, the tumour derives 
from them a strong and often visible impulse ; 
and, over and above the jerk, which they com- 
municate to it, a general thrill of distensive 
pulsation, arising from its own almost erectile 
vascularity, may be felt by the surgeon. Su- 
perficial observation might fail to distinguish 
such a tumour from carotid aneurism, but 
anatomy establishes the diagnosis; for, in each 
movement of deglutition, the diseased mass 
accompanies the larynx, and is seen to rise and 
fall in the neck. Attempts at extirpating 
but, in all cases, largely communicate with the re- 
current nerves, behind the subclavian arteries, and 
furnish numerous continuations, which descending 
around the three great vascular trunks to the areh 
of the aorta, hence prolong themselves to the base 
of the heart. 
