THE SALIVARY GLANDS. 1583 



external auditory meatus, the tympanic plate, the base of the styloid process, and the 

 front of the atlas. These two walls meet above at the Glaserian fissure. The pos- 

 terior wall is prolonged laterally by the posterior belly of the digastric, the stylo- 

 hyoid, and more externally by the sterno-mastoid muscles. The styloid process as 

 it descends becomes internal, and the stylo-glossus and • stylo-pharyngeus, together 

 with the fascia known as the stylo-maxillary ligament, bound the posterior part of 

 the gland internally. In front of the styloid process there is no wall to the space 

 occupied by the parotid, the gland resting against the areolar tissue mixed with fat 

 that lies on the outer wall of the pharynx. The widest part of this cavity is at the 

 surface, where the fascia is connected with the capsule of the gland. The largest 

 expanse of the parotid is, therefore, external. It overlaps the jaw and may reach 

 down to the angle and be separated merely by fibrous tissue from the submaxillary 

 gland. A constant, but very variable, prolongation on the face below the zygoma 

 accompanies the duct. The parotid gland reaches upward between the joint of the 

 jaw and the external auditory meatus and tympanic plate. Internally it lies against the 

 structures above described, always resting on the inner side of the internal pterygoid 

 muscle and extending to the great vessels and nerves which separate it from the 

 side of the pharynx. There may or may not be a higher prolongation inward 

 through the space in front of the styloid process. The internal carotid artery, inter- 

 nal jugular vein, and pneumogastric nerve are close against the lower part of the inner 

 surface of the gland. The external carotid artery enters the gland from the inner 

 side and divides into its temporal and internal maxillary branches, besides giving off 

 the posterior auricular, and sometimes the occipital arteries, within its substance. 

 The external jugular vein is formed within the gland and emerges from its lower side. 

 Near the skull the great vessels and nerves are separated from the gland by the styloid 

 process. The facial nerve enters the gland on its posterior side and passes through 

 it oblicjuely so as to become more superficial as it travels forward, lying external to the 

 external carotid artery and jugular vein. Before emerging from the gland the facial 

 nerve breaks up into its two great divisions, the branches of which begin to subdivide 

 within the glandular mass. The auriculo-temporal nerve also passes through the 

 upper part of the gland, emerging on its outer aspect. A varying number of lym- 

 phatic glands lie in the substance of the parotid, mostly in the more superficial part. 

 They are small and not easy to find. A larger one, said by Sappey to be constant, 

 is in the gland just in front of the ear. 



The parotid or Stenson's duct is formed by two chief tributaries, and emerges 

 from the front of the gland, above its middle, running forward and a little down- 

 ward across the masseter muscle to turn in sharply at its anterior border. It then 

 crosses a collection of fat and runs obliquely through the buccinator muscle and 

 the oral mucous membrane to empty into the vestibule of the mouth opposite the 

 second, often the first, superior molar tooth. The length is some 40 mm. and the 

 diameter 3 mm. The termination is a mere slit. Its walls are firm and resistant. 

 The general direction of the duct is that of a line from the lower side of the concha 

 of the ear to midway between the border of the nostril and the red edge of the lip. 

 The transverse facial artery lies above it, on leaving the gland, and a plexus of veins 

 surrounds it. 



Vessels. — The arteries of the parotid gland are derived from several sources ; 

 although numerous, none of them is large. Besides several small branches from 

 the external carotid itself while in the gland-substance, there are twigs from the 

 temporal, especially from its transverse facial branch, from the posterior auricular, 

 the internal maxillary, and probably from an occasional branch that may pass through 

 the gland. The veiyis form quite a plexus through the gland and open into the sys- 

 tem of the temporo-maxillary and of the external jugular. Of the lymphatics much 

 remains to be learned, but they probably empty into both the deep and the super- 

 ficial cervical nodes. 



Nerves are from the facial, auriculo-temporal, and great auricular, besides sym- 

 pathetic fibres from the carotid plexus. 



The Submaxillary Gland. — This gland, weighing from 7-10 gm., lies 

 largely under cover of the lower jaw, just before the angle, in a fossa on the inner 

 side of the bone. As, however, the skin is carried inward under the jaw at this 



