THE ANATOMY OF THE ADULT HUMAN SALIVARY GLANDS 9 



developed accessory glandular mass extending from the main gland 

 across the masseter to the point of engagement of Stenson's duct in 

 the buccinator muscle (6). 



In this instance only the dorsal members of the earlier periductular 

 group of accessory parotid glands (Fig. i) have been retained in the 

 adult organization, and have produced the extensive prolongation 

 of the main gland along the dorsal border of the duct, while the earlier 

 ventral periductular elements have disappeared, thus freeing this 

 aspect of the duct in its entire transmasseteric course. 



[Further confirmation of the abovc-c.xpressed views in regard to the human asso- 

 ciate or secondary parotid glands is furnished by these structures in some of the 

 lower primates. Thus the human adult of Fig. 3, Part I, corresponds closely in its 

 parotid organization to the specimens of Simia satynis of Fig. 1, Part III, and of 

 Cynoccphalns Immadryas, Fig. 5, Part III. It is not difficult to see in the glan- 

 diferous parotid ducts of Cynocepltalus sphinx (Fig. ,5, Part III), and Macacus 

 nemeslrinns (Fig. 7, Part III) a persistence and further development of the condi- 

 tions presented in the early human fetal stages (Fig. i, Part I), whUe the human 

 adult shown in Fig. 6, Part I, has carried this periductular efHorescence only along 

 the dorsal border of Stenson's duct. Note by the Editors.] 



This latter type of prolongation of the associate parotid lobules 

 along the dorsal border of Stenson's duct is also seen in the human 

 adult shown in Fig. 7. 



The individual represented, on the other hand, in Fig. 8, possesses 

 a parotid which is shortened in the transverse and elongated in the 

 vertical diameter. Stenson's duct, formed by the union of two branches 

 emerging from the ventral margin of the main gland, carries no acces- 

 sory elements throughout its entire transmasseteric course. 



In Fig. 9 the parotid has the more typical adult shape with the dorso- 

 cephalic angle of the irregularly rectangular mass projecting sHghtly 

 along the dorsal border of the duct, marking the first stage of the more 

 extensive periductular development of associated gland masses seen 

 in the previously described instances (Figs. 3, 6, and 7). The rest 

 of the duct is, however, entirely free to its termination, and its forma- 

 tion by confluence of two main branches emerging from the ventral 

 border of the gland is again clearly seen. 



Figure 10 shows an exposure in the human adult of the mesal sur- 

 face of the gland, with its relations to internal (75) and external {14) 

 pterygoid muscles, external carotid (29) and internal maxillary (jo) 

 arteries, and to the temperomaxillary vein (35) . 



