THE TONSIL. 131 



In the palate the muscle incloses the levator palati and azygos uvulae 

 between its two strata. 



Action. Taking its fixed point at the thyroid cartilage the muscle de- 

 presses and makes tense the soft palate. 



During the act of swallowing both muscles move back the lower edge 

 of the soft palate towards the pharynx ; and approaching each other, form 

 an oblique plane for the downward direction of the food ; in that state the 

 uvula lies in the interval between the two. 



The AZYGOS UVULAE (fig. 29, D ) is situate along the middle line of the 

 velum near the posterior surface. The muscle consists of two narrow 

 slips of pale fibres, which arise from the spine at the posterior border of 

 the hard palate, or from the contiguous aponeurosis, and end inferiorly in 

 the tip of the uvula. Behind this muscle, separating it from the mucous 

 membrane, is the thin stratum of the palato-pharyngeus. 



Action. Its fibres elevate the uvula, shortening the mid part of the 

 soft palate, and direct that process backwards. 



The tonsil, K, is a collection of follicular capsules resembling those on 

 the dorsum lingua 1 , which is placed close above the base of the tongue, 

 and between the arches of the soft palate. Each is roundish in shape, but 

 variable in size ; and apertures are apparent on its surface. Externally 

 the tonsil is situate opposite the superior constrictor muscle and the angle 

 of the lower jaw ; and when enlarged it may press against the internal 

 carotid bloodvessel. 



The apertures on the surface lead to rounded terminal recesses or hol- 

 lows which are lined by mucous membrane. Around each recess is a 

 layer of small closed capsules, which are seated in the tissue beneath the 

 mucous membrane, and are filled with a grayish substance containing 

 cells and nuclear-looking bodies. No openings from the capsules are to be 

 recognized in the recesses. 



Its arteries are numerous and are derived from the facial, lingual, as- 

 cending pharyngeal, and internal maxillary branches of the external 

 carotid. Its veins have a plexiform arrangement on the outer side. 

 Nerves are furnished to it from the fifth and glosso-pharyngeal nerves. 



The mucous membrane of the pharynx is continuous anteriorly with the 

 lining of the mouth, nose, and larynx. Covering the soft palate and its 

 numerous small glands (palatine), the membrane is continued to the ton- 

 sils on each side, and is prolonged by the Eustachian tube to the tym- 

 panum. In front of each arytrenoid cartilage it incloses a mass of muci- 

 parous glands (arytrenoid). Inferiorly, it is continued by the ossophagus 

 to the stomach. 



The mucous membrane is provided with more glands in the upper, than 

 in the lower part of the pharynx; and its character, near the different 

 apertures, resembles that of the membrane lining the cavities communi- 

 cating with the pharynx. Its epithelium is scaly below the nares (Henle) ; 

 but is columnar and ciliated above that spot, where only the air is trans- 

 mitted. 



Beginning of the oesophagus. This tube is much smaller than the pha- 

 rynx, and the walls are flaccid. For the commencement, and its connec- 

 tions in the neck, see p. 121. 



The gullet consists of two layers of muscular fibres, with a lining of 

 mucous membrane. The external layer is formed of longitudinal fibres, 

 which begin opposite the cricoid cartilage by three bundles, anterior and 

 two lateral ; the former is attached to the ridge at the back of the carti- 



