884 THE ORGANS OF DIGESTION. 



The muscles of the soft palate are five on each side : the Levator palati, 

 Tensor palati, Azygos uvulae, Palato-glossus, and Palato-pharyngeus (see page 329). 

 The following is the relative position of these structures in a dissection of the soft 

 palate from the posterior or nasal to the anterior or oral surface : Immediately 

 beneath the nasal mucous membrane is a thin stratum of muscular fibres, the 

 posterior fasciculus of the Palato-pharyngeus muscle, joining with its fellow of 

 the opposite side in the middle line. Beneath ^this is the Azygos uvulae, consist- 

 ing of two rounded fleshy fasciculi, placed side by side in the median line of the 

 soft palate. Next comes the aponeurosis of the Levator palati, joining with the 

 muscle of the opposite side in the middle line. Fourthly, the anterior fasciculus 

 of the Palato-pharyngeus, thicker than the posterior, and separating the Levator 

 palati from the next muscle, the Tensor palati. This muscle terminates in a tendon 

 which, after winding round the hamular process, expands into a broad aponeurosis 

 in the soft palate, anterior to the other muscles which have been enumerated. 

 Finally, we have a thin muscular stratum, the Palato-glossus muscle, placed in 

 front of the aponeurosis of the Tensor palati, and separated from the oral mucous 

 membrane by adenoid tissue. 



The Tonsils (amygdalae) are two prominent bodies situated one on each side of 

 the fauces, between the anterior and posterior pillars of the soft palate. They are 

 of a rounded form, and vary considerably in size in different individuals. A 

 recess, the fossa supra-tonsillaris, may be seen, directed upward and backward 

 above the tonsil. His regards this as the remains of the lower part of the second 

 visceral cleft. It is covered by a fold of mucous membrane termed the plica 

 triangularis. Externally the tonsil is in relation with the inner surface of the 

 Superior constrictor, to the outer side of which is the Internal pterygoid muscle. 

 The internal carotid artery lies behind and to the outer side of the tonsil, and 

 nearly an inch (20 to 25 mm.) distant from it. It corresponds to the angle of the 

 lower jaw. Its inner surface presents from twelve to fifteen orifices, leading into 

 small recesses, from which numerous follicles branch out into the substance of the 

 gland. These follicles are lined by a continuation of the mucous membrane of the 

 pharynx, covered with epithelium ; around each follicle is a layer of closed cap- 

 sules imbedded in the submucous tissue. These capsules are analogous to those of 

 Peyer's glands, consisting of adenoid tissue. No openings from the capsules into 

 the follicles can be recognized. They contain a thick grayish secretion. Sur- 

 rounding each follicle is a close plexus of lymphatic vessels. From these plexuses 

 the lymphatic vessels pass to the deep cervical glands in the upper part of the neck, 

 which frequently become enlarged in affections of these organs. 



The arteries supplying the tonsil are the dorsalis linguae from the lingual, the 

 ascending palatine and tonsillar from the facial, the ascending pharyngeal from the 

 external carotid, the descending palatine branch of the internal maxillary, and a 

 twig from the small meningeal. 



The veins terminate in the tonsillar plexus, on the outer side of the 

 tonsil. 



The nerves are derived from Meckel's ganglion and from the glosso-pharyngeal. 



THE SALIVARY GLANDS (Fig. 483). 



The principal salivary glands communicating with the mouth and pouring 

 their secretion into its cavity are the parotid, submaxillary, and sublingual. 



The parotid gland, so called from being placed near the ear (napd, near : o>c, 

 aroc, the ear), is the largest of the three salivary glands, varying in weight from 

 half an ounce to an ounce. It lies upon the side of the face immediately below 

 and in front of the external ear. It is limited above by the zygoma ; below, by 

 the an ! e of the jaw and by a line drawn between it and the mastoid process : 

 anteriorly, it extends to a variable extent over the Masseter muscle ; posteriorly, 

 it is bounded by the external meatns. the mastoid process, and the Sterno-nmstoid 

 and Digastric muscles, slightly overlapping the two muscles. 



