THE SALIVARY GLANDS. 521 



numerous simple follicles, and its upper part, compound racemose 

 glands. Their secretion lubricates the parts, and also the surface of 

 the food. It may likewise aid the saliva in its chemical action. 

 Throughout the whole length of the oesophagus, and especially in a 

 circular group around its lower end, there are also numerous compound 

 mucous glands, which perform similar offices. 



Of the three pairs of salivary glands, the parotid glands are by 

 far the largest, weighing from 5 to 8 drachms each. They are placed 

 one on each side of the face, between the ear (jwpd, near, OUT, WTO?, 

 the ear) and the lower jaw, which they overlap, being there supported 

 by their ducts and bloodvessels, and by a strong fascia. The facial 

 nerves pass through the glands. The principal mass of each gland 

 occupies the position above indicated, and likewise penetrates amongst 

 the muscles and vessels of this region ; but a secondary or accessory 

 portion, soda parotidis, extends forwards along the excretory duct. 

 This canal, named the Stenonian duct, runs forward from the gland, 

 over the masseter muscle, passes obliquely through the buccinator 

 muscle, and, opposite the second upper molar tooth, opens by a narrow 

 orifice into the mouth. It is about 2J inches long, and about the 

 diameter of a crowquill, but its orifice is very minute. The gland it- 

 self consists of numerous compressed lobes, held together by the 

 ramified ducts and bloodvessels, and by areolar tissue. The lobes are 

 again divided into lobules, each of which is a minute racemose gland, 

 the branched ducts of which terminate in vesicles, about y^^th of an 

 inch in diameter, Fig. 42, c, each being surrounded by a network of 

 capillaries. The saliva, secreted from the blood into these vesicles, 

 flows along the smaller branches of the ducts, into the main canal or 

 duct of Steno, and is thence poured into the mouth at a place suitable 

 for moistening the dry food, and for being mixed with the alimentary 

 mass. The submaxillary glands are placed, one on each side, beneath 

 the horizontal part of the lower jaw, attached by their ducts and 

 bloodvessels, and supported by the cervical fascia and certain muscles. 

 Each gland is of a roundish shape, and weighs from 2 to 2J drachms ; 

 its structure resembles that of the parotid. Its chief duct, thinner 

 than that of the parotid, is named the Whartonian duct, and is about 

 2 inches long ; it runs forwards between the muscles, beneath the sub- 

 lingual gland, to the side of the frgenum of the tongue, where it opens 

 upon a small eminence close to the duct of the opposite side. These 

 glands, therefore, discharge their saliva, not outside the jaws, like the 

 parotid glands, but inside the lower dental arch, their secretion being 

 pressed up into the mouth by the motions of the tongue. The sub- 

 lingual glands, the smallest of the salivary glands, are somewhat 

 almond-shaped, and weigh each about one drachm ; they form two 

 narrow, oblong ridges, about 1J inch long, placed, one on each side, 

 beneath the tongue. Their structure resembles that of the other sali- 

 vary glands, but, instead of having a common duct, the several lobules 

 open into from eight to twenty ducts, named the Rivinian ducts, some 

 of which, including one large duct named the duct of Bartholin, join 

 the Whartonian duct, as it runs for a certain distance immediately 



