THE HEAD AND NECK, POSTERIOR. 143 



in front of this blind depression the " V-shaped " group of 

 circumvallate papillae. 



A third mass of adenoid tissue is seen at the base of the 

 tongue and in front of the epiglottis ; this is the lingual 

 tonsil. 



Below and behind the base of the tongue stands the epi- 

 glottis to protect the opening of the larynx, which presents 

 posterior and inferior to it. 



.The epiglottis is connected to the base of the tongue by 

 the general covering of mucous membrane which is thrown 

 into three folds, one in the medial line and two laterally, 

 which are called the median (fraenum epiglottidis) and 

 lateral glosso-epiglottic folds. On both sides of the frae- 

 num epiglottidis is a shallow depression the glosso-epi- 

 glottic pouch. 



From the sides of the epiglottis backward to the top of 

 the larynx the mucous membrane is thrown into a promi- 

 nent ridge, the aryteno-epiglottic fold. The upper mar- 

 gins and cornua of the thyroid cartilage can be easily appre- 

 ciated. 



DISSECTION. 



Remove the mucous membrane which covers the interior of the pharynx, 

 the posterior surface of the soft palate, and the posterior faucial arches. 



In dissecting the muscles of the palate and the pharynx (interior), it must 

 be remembered that these are very thin, and their outlines not at all as distinct 

 as the illustrations in the text-books would lead one to think. The student 

 should do the best he can with the aid of such illustrations and the descriptive 

 anatomy to find the various parts. 



Palatopharyngeus. 



The thin muscular layer is attached to the soft palate near 

 the median line and arches outward and downward, form- 

 ing the posterior palatine arch, to be attached below to the 

 posterior border of the thyroid cartilage and the lateral wall 

 of the pharynx. At the soft palate the fibres of the muscle 



