THE PHARYNX. 985 
3y the contraction of the palato-pharyngei muscles, which are enclosed within the 
palatine arches, the sides of the isthmus can be approximated, like two curtains, and its 
size correspondingly diminished. When, at the same time, the uvula and soft palate are 
elevated, and the whole pharynx in this region is narrowed by the contraction of the 
superior constrictor, the aperture can be completely closed, and the oral separated from 
the nasal pharynx, as in the acts of swallowing and vomiting. 
The tonsils (tonsillee palatine, amygdale) are two large, oval masses of lymphoid 
tissue which are embedded in the lateral walls of the oral pharynx, between the 
anterior and posterior palatine arches (Fig. 661). As already pointed out, there is 
in this region a triangular interval (the sinus tonsillaris), situated between the two 
Internal jugular vein Hypoglossal nerve 
Spinal accessory nerve | Internal carotid artery 
Digastric muscle : . 
gastric m | | Pneumogastric nerve 
Nee Sympathetic 
Pa \ \ Ascending pharyngeal artery 
A \-'- E Odontoid process 
: _ ha 
| 
Glosso- )™~ 
pharyngeal nerve ~~ _| 
Parotid gland [Ss 
Temporo- _Post-pharyngeal 
maxillary vein 
— lymphatic gland 
External can ae 
artery a _ Superior 
Styloglossus- Yea constrictor muscle 
Ascending __Posterior palatine 
palatine : artery al arch 
— Tonsil 
Pharyngo-epiglottie 
Epiglottis fold 
Frenulum 
epialontidia Anterior palatine 
: arch 
Circumvallate 
papille 
Masseter— 
Pharyngeal portion_ 
of tongue 
7 Raphe of tongue 
Conical papilla 
Fungiform papilla 
Buecinator 
Fic. 664.—HorizontTat SecTION THROUGH MOUTH AND PHARYNX AT THE LEVEL OF THE TONSILS. 
The stylopharyngeus, which is shown immediately to the inner side of the external carotid artery, and the 
prevertebral muscles, are not indicated by reference lines. 
palatine arches and the side of the tongue. The greater part of this interval is 
occupied by the tonsil. In its upper part, however, above the tonsil, there is 
usually found a variably-developed depression already referred to as the supra- 
tonsillar fossa. 
The tonsil lies under cover of the ramus of the jaw, and corresponds in 
position to a point a little above and in front of its angle. Its inner or pharyngeal 
surface is prominent, and closely beset with numerous deep, pit-like depressions—the 
crypts of the tonsil. These crypts are most numerous in the upper part of the mass, 
where, in particular, they form a series of irregular inter-communicating passages. 
The outer or attached surface is enclosed in a distinct fibrous ¢: ipsule connected 
with the pharyngeal aponeurosis, outside which lie the superior constrictor of the 
pharynx and the internal pterygoid muscles (Fig. 664). 
* 
