NASAL CAVITY IN THE HORSE. 
9 
in it, and being longer in contact with the sensitive membrane by 
which it is lined, contributes to the acuter sense of smell. It is 
the portion of the cavity more particularly devoted to the sense 
of smell. You will not forget the use you may make of it in 
fracture of the nasals; an elevator may be introduced below, or 
the trephine may be applied through its whole extent. 
The central meatus lies between the two turbinated bones. It 
receives every natural or morbid discharge from the maxillary and 
other sinuses, for there is a valve-like opening into these sinuses, 
two-thirds of the way up the meatus, and under the superior 
turbinated bone. There is only one spot, pointed out to you by 
these preparations, at which the trephine could possibly be ap¬ 
plied. 
The largest channel is along the floor of the nasal cavity, un¬ 
der the inferior turbinator, and extending from the anterior to the 
posterior termination of the cavity. It is the proper air-passage ; 
and because it has this important function it is out of the reach 
of injury or violence, and is not clogged by any discharges but 
those that proceed from the respiratory tubes beyond the nostril, 
or an exceedingly unfrequent regurgitation of the matter from the 
stomach. The distinct offices of these channels, and their dif¬ 
ferent construction, admirably adapted for the performance of 
each, deserve your attention. 
The Maxillary and other Sinuses .—When the superior turbi¬ 
nated bone is removed, the maxillary sinus, of which I shall 
have to speak under another system, is exposed, or, rather, be¬ 
comes a portion of the nasal cavity. With the maxillary sinuses, 
the frontal, the superior aethmoidal, and the sphenoidal in the 
horse, and the palatine cells in the ox, communicate. Altogether 
they form a vast hollow, and under some diseases, and particu¬ 
larly under glanders, contain a great quantity of purulent or 
other fluid. The maxillary sinus freely communicates with the 
others, and it opens into the nasal cavity under the superior tur¬ 
binated bone. 
The Lachrymal Duct .—This is the channel through which the 
superfluous tears are conveyed to the lower part of the nostril ; 
and it is exposed to view when the superior turbinated bone is re¬ 
moved. There is, behind the tubercle on the lachrymal bone, 
varying in size in our different patients, and which will be more 
particularly described when we treat of the age, a funnel-shaped 
depression, into which the superfluous fluid of the eye is received 
through the puncta on either side of the caruncle. I will not de¬ 
tain you by entering into the dispute, whether the membrane by 
which this funnel is lined is a proper sac; but it is, at least, an 
vol. v. c 
