THE RECURRENT NERVES. 
115 
placed before the dog, and the nose and the mouth being stimu- 
lated by the smell and the taste of the viands, successive portions 
will betaken, and pass through the mouth and enter the gullet, 
and be forced along it by other portions of food driven on by the 
dorsum of the tongue and the constrictors of the pharynx, until 
the stomach and the oesophagus are perfectly filled. This has 
been put to the test of experiment. The oesophagus has been 
found distended with food — filled from the top to the bottom — 
and when the experiment has been pushed far enough, the sto- 
mach, too, has been filled. The influence of the recurrent nerve 
has been cut off', and although the smell and taste remain, and 
the power of the masticatory muscles, and, partially, the power of the 
constrictors of the pharynx, that of the muscles of the oesophagus 
has ceased, and even the very consciousness of the presence of 
food and the distention which it occasions. Nothing can be 
more satisfactory than this. Before this division, the muscles of 
the gullet would have been excited to forcible and spasmodic 
action, without any dictation, and in defiance of the control of 
the will, and the animal would appear to be threatened with suf- 
focation every instant : but, the presiding power being withdrawn, 
not only one small portion of food is arrested in its course, but the 
gullet is crammed from one end to the other, and yet all is still. 
The Thyroid Branches . — Before its journey is completed, this 
right recurrent distributes some branches to the thyroid glands 
resting upon the trachea and the larynx, and covered by the sterno 
and omo-hyoid, and the sterno thyroid muscles. They are of 
considerable size in the young subject, and they are, compared 
with their size, most abundantly supplied with blood. We call 
them glands, and probably they are so ; but they have no secern- 
ing or excretory vessels, and appear to be little more than masses 
of condensed pulpy matter. They are much influenced by disease, 
and particularly by diseases of a scrofulous character, and occa- 
sionally assume a state of frightful enlargement and disorganiza- 
tion ; but, as I am compelled to confess that I have no satisfactory 
notion of their functions, and that the crude ideas which 1 may have 
on this subject I cannot elucidate by experiment, I will therefore 
only say, that they receive branches from the recurrent nerve. 
Termination of the right Recurrent Nerve . — The right recur- 
rent nerve continues its course, and, arriving at the upper part of 
the neck, it is evidently making its way to the back of the thy- 
roid cartilage. Ere it arrives at this point, it passes by the edge 
of the inferior pharyngeal constrictor muscle, and bestows some 
filaments on it; thus more closely identifying that muscle with 
the ultimate function of the recurrent nerve — to be presently de- 
scribed. Having now reached the back of the thyroid cartilage. 
