THE PHARYNX 407 
laryngis occupies the greater part of the ventral wall or floor of the pharynx; it 
is open except during deglutition. Behind this is the aditus cesophagi, the entrance 
to the cesophagus. 
The wall of the pharynx comprises, from without inward, the muscles, the 
pharyngeal aponeurosis, and the mucous membrane. 
The muscles of the pharynx (Mm. pharyngis) (Figs. 332, 333) are covered 
by the pharyngeal fascia, which is attached to the base of the skull, the great cornu 
of the hyoid bone, and the thyroid cartilage of the larynx. They are as follows: 
1. The stylo-pharyngeus arises from the medial surface of the dorsal third 
of the great cornu of the hyoid bone, passes ventro-medially, and enters the wall of 
the pharynx by passing between the pterygo-pharyngeus and palato-pharyngeus. 
Its fibers radiate, many bundles passing forward, others inward or backward be- 
neath the hyo-pharyngeus. It raises and dilates the pharynx to receive the bolus 
in swallowing. 
2. The palato-pharyngeus arises chiefly by means of the aponeurosis of the 
soft palate from the palatine and pterygoid bones; some fibers are attached to the 
anterior wide part of the Eustachian tube. Its fibers pass backward on the lateral 
wall of the pharynx, and are inserted in part into the upper edge of the thyroid 
cartilage, in part turn inward to end at the median fibrous raphé. Its action is to 
shorten the pharynx, and to draw the larynx and cesophagus toward the root of the 
tongue in swallowing.! 
3. The pterygo-pharyngeus is flat and triangular. It lies on the anterior part 
of the lateral wall of the pharynx. It arises from the pterygoid bone above the 
preceding muscle-——from which it is not distinctly separated,—crosses the levator 
palati, and is inserted into the median raphé. Its action is similar to the preceding. 
4. The hyo-pharyngeus may consist of two parts: 
(a) The kerato-pharyngeus is a small and inconstant muscle which arises 
from the medial surface of the great cornu of the hyoid bone near its ventral end. 
Tt passes upward and backward on the lateral face of the palato-pharyngeus, 
turns toward the raphé, and spreads out under the next muscle. 
(b) The chondro-pharyngeus, broad and fleshy, arises from the thyroid cornu 
of the hyoid bone and by a thin fasciculus from the lamina of the thyroid cartilage. 
The bundles spredid out and end at the median raphé. The posterior part dips 
under the thyro-pharyngeus, while the anterior part overlies the pterygo- and 
palato-pharyngeus. 
5. The thyro-pharyngeus arises from the lateral surface of the lamina of the 
thyroid cartilage on and behind its oblique line. Its fibers pass forward and 
medially to the median raphe. 
6. The crico-pharyngeus arises from the lateral part of the arch of the cricoid 
cartilage and ends at the raphé. The fibers are directed upward, forward, and 
inward; they blend behind with the longitudinal fibers of the cesophagus. 
The last three muscles are constrictors of the pharynx. 
The pharyngeal aponeurosis is attached to the base of the cranium. It is 
well developed on the medial face of the palato-pharyngeus muscle and forms a 
median raphé pharyngis dorsally, which is wide in its posterior part. 
The mucous membrane of the pharynx is continuous with that of the several 
cavities which open into it. It is thin and closely adherent to the base of the skull 
in the vicinity of the posterior nares, where the muscular wall is absent. Behind 
the Eustachian openings there is a median cul-de-sac, the pharyngeal recess (Re- 
cessus pharyngeus). The recess is somewhat variable, but is usually about an inch 
in depth and will admit the end of the finger. In the ass and mule it is much deeper. 
Here also the muscular wall is absent and the mucous membrane lies against the 
1 Vermeulen states that the pharyngeal orifice of the Eustachian tube is opened by the 
jcontraction of that part of the muscle which is attached to the tube. 
