253 CIRCULATORY SYSTEM. 



afterwards becomes the External jugular; but, occasionally, it 

 ends wholly, or in part, in the Internal jugular. 



The Internal Maxillary Vein ( Vena Maxillaris Internet) is de- 

 rived from the terminating ramifications of all the arteries into 

 which the internal maxillary is divided ; it is, therefore, com- 

 posed of the spheno-palatine vein, which brings the blood from 

 the nose, of the infra-orbital, of the pterygoids, inferior max- 

 illary, deep-seated temporal, and so forth, with the exception 

 of the vein, which might belong to the middle artery of the 

 dura mater, but which does not exist according to Portal and 

 to Hippolytus Cloquet. By the aid of the spheno-palatine vein, 

 the internal maxillary communicates with the sinuses in the 

 bottom of the cranium, by branches, called the Emissary Veins 

 of Santorini,* which pass through the foramen ovale, rotun- 

 dum, and spinale. It also communicates with the plexus of 

 veins on the side of the pharynx. 



The External Jugular Vein (Vena Jugularis Externa) is ge- 

 nerally the continuation of the temporal. It descends on the 

 neck almost vertically, between the platysma myodes and the 

 sterno-mastoideus, in the direction of the fibres of the first, and 

 crossing those of the latter obliquely. Just behind the clavicle, at 

 the external margin of the sterno-mastoideus, it opens into the 

 subclavian vein, in front of the scalenus anticus muscle. Some- 

 times, instead of one trunk only, there are two or three, which 

 unite at a variable distance above the subclavian. This vein 

 varies also in its size, and in the branches from which it is 

 made up: sometimes it receives the facial vein, and on other 

 occasions the latter runs, as stated, into the internal jugular. 

 The condition and arrangement of the internal and external 

 jugulars are, indeed, so inconstant, in regard to the trunks 

 that compose them, that it is scarcely possible to give more 

 than a very general description of them with tolerable accu- 

 racy. 



The external jugular, in going down the neck, anastomoses 

 more or less with the internal jugular, either directly or by its 

 branches: one of these anastomoses is found near the angle of 



* Obs. Anat. chap. Hi. p. 74. 



