Page 366 - Anatomy and Physiology of Farm Animals, 8th Edition

The Respiratory System / 351

(A) (B)
VetBooks.ir

Ox
Horse
(C) (D) (E)

Dog
Sheep
Pig
Figure 19-1. External nares of various species. The horse (A) lacks a planum, its nose being instead cov-
ered with fine hair. The ox (B) possesses a nasolabial planum, and the small ruminants (C) and dogs (E) have
a nasal planum. The pig’s external nose (D) features a rostral planum that is supported by a rostral bone.

scroll‐like conchae (turbinate bones) aris- longitudinally arrayed nasal meatuses
ing from the bones of the lateral wall (Figs. 19‐2 and 19‐3). The dorsal nasal
(Figs. 19‐2 and 19‐3). The two major con- meatus is between the dorsal concha and
chae (dorsal concha and ventral concha) the roof of the nasal cavity. The middle
occupy rostral parts of the nasal cavity; nasal meatus is between the two conchae.
caudal parts are filled with ethmoidal The ventral nasal meatus is between the
conchae. The vascular mucous membrane ventral concha and the floor of the nasal
covering these conchae helps to warm and cavity. The common nasal meatus com-
humidify inspired air. The mucous mem- municates between the others and is adja-
brane investing the ethmoidal conchae is cent to the nasal septum. A nasogastric
the olfactory epithelium. It contains the tube introduced through the nostrils
sensory endings of the olfactory nerve, into the nasal cavity and advanced into
which mediates the sense of smell (see the esophagus for administration of
Chapter 12). medications is directed into the space
The actual air space of each half of the that is the junction of the common and
nasal cavity is divided by the conchae into ventral nasal meatus.