232 THE VISCERA. 
nasopharynx is continuous craniad by the choaneze with the 
nasal cavity; it forms a horizontal tube between and ventrad 
of the perpendicular plates of the palatine bones, and has the 
same craniocaudal extent as the soft palate. Its dorsal wall 
lies against the basis cranii and the longus capitis muscles; its 
lateral walls against the pterygoid muscles and the perpendic- 
ular plates of the palatine bones; its ventral wall is the soft 
palate. At the middle of its length, at the junction of its 
dorsal and lateral wall, are two longitudinal slits about three 
millimeters long. These are the medial openings of the 
Eustachian tubes, by which the nasopharynx communicates 
with the tympanic cavity. 
The pharynx proper, situated caudad of the nasopharynx, 
is smaller than the latter. It is bounded craniad by the 
epiglottis and the margin of the soft palate, and is continuous 
between the two, by the isthmus faucium, with the mouth 
cavity. Its floor is formed by the cranial end of the larynx. 
At its caudal end it passes dorsally into the cesophagus, while 
ventrally it communicates with the larynx. Its walls are 
muscular. 
MUSCLES OF THE PHARYNX (Fig. 96).—M. glossopharyn- 
geus (z). 
Origin.—Some fibres on the ventral and lateral part of the 
genioglossus (/) leave that muscle near its caudal end. They 
form a thin band of diverging fibres which pass outside of the 
cranial horn of the hyoid. <A similar sheet of fibres leaves the 
midventral part of the styloglossus (e). The two sheets unite 
and the united muscle crosses the hyoid, turns dorsad, and has 
its 
Jnsertion into the median dorsal raphe of the pharynx. 
Action.—Constrictor of the pharynx. 
M. constrictor pharyngis inferior (4).—A thin sheet of 
muscle covering the sides of the pharynx at its caudal end. 
Origin from the lateral surfaces of the thyroid and the 
cricoid cartilages. The fibres pass dorsad and craniad, the 
cranial ones covering the fibres of the middle constrictor (7). 
Insertion.—The median longitudinal raphe on the dorsum 
.of the pharynx. The caudal fibres are transverse and contin- 
