426 



SALIVARY GLANDS. 



slightly viscid saliva by their orifices, which 

 are visible to the unassisted eye. 



We have already stated that the posterior 

 part of the sublingual gland is occasionally 

 represented by one or more distinct glands 

 in juxta-position, each furnished with a very 

 short excretory duct. These distinct lobes of 

 the gland are in every way analogous to one 

 of the molar glands or larger labial. It will 

 thus be observed that the transition of the 

 primary to the subsidiary glands is by no 

 means rapid, but that they run the one into 

 the other by insensible gradations, the sub- 

 lingual gland passing from the one series into 

 the other. A molar, labial, or buccal gland, 

 with its excretory duct, might then be not 

 inaptly compared, according to its size, to a 

 secondary or tertiary lobule of the parotid, or 

 submaxillary. 



The labial glands form a series of closely 

 packed small spheroidal glands, of consider- 

 able density, situated in the areolar tissue 

 between the mucous membrane of the mouth 

 and the orbicularis oris muscle, and in relation 

 above and below, consequently, with the upper 

 and lower lip. They are not of uniform 

 volume or number. Sebastian* has observed 

 as many as fifty-seven in the lower lip, and 

 in other instances from thirteen to twenty- 

 one, their size increasing in the inverse 

 ratio to their number. They are more nu- 

 merous in the infant than in the adult. Their 

 excretory ducts open perpendicularly or ob- 

 liquely into the vestibule of the mouth on the 

 posterior or free surface of the labial mucous 

 membrane. They are not visible to the eye 

 when the lips are in their natural lax position, 

 but when the latter are everted, so that the 

 mucous membrane is rendered tense, they 

 form considerable projections. 



The buccal glands are exactly analogous 

 to the labial glands in form and position, being 

 irregularly spheroidal, and placed between the 

 buccinator and mucous membrane, and open 

 by the orifices of distinct ducts on to the free 

 surface of the latter. They are, however, 

 smaller. 



The molar glands two, three, or four in 

 number form an exception as regards their 

 situation to the above glands, being placed 

 between the buccinator and masseter muscles. 

 They are also larger and more dense, being 

 composed of several lobes. The ducts ter- 

 minate by opening on to the mucous mem- 

 brane at the posterior part of the cheek. 

 In a subject we recently examined, their ter- 

 minal orifices were arranged horizontally at 

 unequal distances from each other, on a level 

 with the orifice of Steno's duct, but more 

 than half an inch behind it. They were five 

 in number. We have not succeeded in observ- 

 ing the communications which the ducts of 

 one or more of these glands is stated by some 

 anatomists to establish with the duct of the 

 parotid. 



The palatine glands are very numerous and 



* Sebastian, Becherch.es sur les Glandes Labialcs, 

 Annales dc la Chirurgie. Paris, 1842. t. vi. 



small, and situated partly between the mucous 

 membrane and the palatine arch, and partly 

 between the mucous and muscular layers of 

 the soft palate. The former are situated on 

 either side of the median line, and form a 

 thick layer, being more closely aggregated 

 together in the front and behind than in the 

 middle, opening on to the mucous membrane 

 by distinct orifices. The latter, smaller than 

 the former, exist both on the upper and lower 

 surface of the velum, and are continuous 

 below, where they are more numerous than 

 above, with the glands of the hard palate. 



The posterior lingual glands are placed at 

 the back part of the tongue, directly behind 

 the large papillae, which form a distinct pro- 

 minence at this part. They are spheroidal, 

 and have remarkably short excretory ducts, 

 the circular orifices of which, however, are 

 distinctly visible. 



The last glands to which we would direct 

 attention are two in number, and from their 

 situation may be appropriately termed the 

 anterior lingual glands. They have been re- 

 cently described by Blandin, Nuhn*, and 

 Schlemin, as being situate below the apex of 

 the tongue, between the lower longitudinal 

 and transverse muscular fibres, and pouring 

 their secretion during the movements of that 

 organ on to the mucous membrane beneath 

 the tip. They have only as yet been disco- 

 vered in man and the ouran-outan. We have 

 observed them on the inferior surface of the 

 tongue, half an inch behind its anterior border, 

 immediately above the longitudinal muscular 

 fibres, one on either side of the median line, 

 and about two-thirds of an inch long. Broad 

 behind and narrow in front, they are separated 

 from each other in the former direction by an 

 interval of about half an inch, in the latter 

 are almost in mutual contact. Their direction 

 therefore is obliquely from behind forwards 

 and inwards (fg. 305, b). Each gland is fur- 



Fig. 305. 



a. Bristles in the orifices of the ducts of the left 

 anterior lingual gland, b. The right anterior lin- 

 gual gland, c. The raphe' of the tongue. 



nishcd with three or four delicate ducts, given 

 off" from its lower surface, and which perforate 

 the mucous membrane obliquely parallel to 

 the long axis of the gland (fig. 305, a). These 

 glands are of less consistence than the molar 

 or labial. We have met with one instance in 



* A. Xuhn, iiber eine bis jetzt noch nicht naher 

 beschriebene Driise im Innern cler Zungenspitze. 

 Mannheim, 1845, quoted by Valentin in Physiologic 

 der Menschcn, 1847, zweite Atiflage. 



