368 VEINS OF THE HEAD AND NECK. 



bral veins : they are also absent in the large trunks, as in the venae 

 cavae, venae azygos, innominatae, and iliac veins. 



Sinuses are venous channels, excavated in the structure of an organ, 

 and lined by the internal coat of the veins ; of this structure are the 

 sinuses of the dura mater, whose external covering is the fibrous tissue 

 of the membrane, and the internal, the serous layer of the veins. The 

 external investment of the sinuses of the uterus is the tissue of that 

 organ ; and that of the bones, the lining membrane of the cells and 

 canals. 



Veins, like arteries, are supplied with nutritious vessels, the vasa 

 vasorum ; and it is to be presumed that nervous filaments are distri- 

 buted in their coats. 



I shall describe the veins according to the primary division of the 

 body ; taking first, those of the head and neck ; next, those of the 

 upper extremity ; then, those of the lower extremity ; and lastly, the 

 veins of the trunk. 



VEINS OF THE HEAD AND NECK. 



The veins of the head and neck may be arranged into three groups, 

 viz. 1. Veins of the exterior of the head. 2. Veins of the diploe 

 and interior of the cranium. 3. Veins of the neck. 



The veins of the exterior of the head are the 



Facial, 



Internal maxillary, 



Temporal, 



Temporo-maxillary, 



Posterior auricular, 



Occipital. 



The Facial vein commences upon the anterior part of the skull in a 

 venous plexus, formed by the communications of the branches of the 

 temporal, and descends along the middle line of the forehead, under 

 the name of frontal vein, to the root of the nose, where it is connected 

 with its fellow of the opposite side by a communicating trunk which 

 constitutes the nasal arch. There are usually two frontal veins 

 which communicate by a transverse inosculation ; but sometimes the 

 vein is single and bifurcates at the root of the nose, into the two an- 

 gular veins. From the nasal arch, the frontal is continued downwards 

 by the side of the root of the nose, under the name of the angular 

 vein ; it then passes beneath the zygomatic muscles and becomes the 

 facial vein, and descends along the anterior border of the masseter 

 muscle, crossing the body of the lower jaw, by the side of the facial 

 artery, to the submaxillary gland, and from thence to the internal 

 jugular vein in which it terminates. 



The branches which the facial vein receives in its course are, the 



