516 



THE VKINS OF THE HEAD AXD NECK. 



lower jaw, and into which one or two small veins issuing from the tympanum by 

 the fissure of Glaser pour their contents ; parotid branches from the gland ; and one 

 or two transverse facial veins from the surface of the masseter muscle. 



The internal maxillary vein is a short vessel, often double, which passes 

 backwards from the pterygoid plexus in the zygomatic fossa, in company with the 

 first part of the internal maxillary artery, and joins the temporal vein behind the 

 ramus of the jaw. The pterygoid plexus, corresponding to the second and third 

 parts of the internal maxillary artery, is a network of large veins covering both sur- 

 faces of the external pterygoid muscle, and extending also over the inner surface of 







Fig. 402. DIAGRAMMATIC VIEW OF THE SINUSES OF THE DURA MATER AND SOME OF THE DEEP 



VEINS OF THE HEAD AND NECK. (Allen Thomson.) \ 



The greater part of the calvaria has been removed, but an arched strip has been left in the region of 

 the superior longitudinal sinus. The occipital portion of the skull has been entirely removed so as to 

 expose the lateral sinus and its termination in the internal jugular vein, a, a, falx cerebri ; b, b', ten- 

 torium cerebelli ; c, zygoma ; d, malar bone; e, angle of jaw ; /, spinous process of axis ; 1, superior 

 longitudinal sinus ; 2, inferior longitudinal sinus ; 2, to 3, straight sinus ; 2', veins of Galen ; 3, 

 lateral sinus, descending to 4, the commencement of the internal jugular vein ; 3', superior petrosal 

 sinus ; 4, 4, internal jugular vein ; 5, superficial temporal vein ; 6, middle temporal ; 8, internal max- 

 illary joining the common temporal vein to form the temporo-maxillary trunk ; 8', pterygoid plexus 

 receiving the deep temporal veins ; 9, anterior division of the temporo-maxillary trunk, joining the 

 facial vein ; 9', inferior palatine vein ; 10, common facial ; 10', submental; 10", upper part of facial ; 

 11, posterior auricular ; 12, 12, vertebral ; 13, 13, dorsal spinal veins ; 14, occipital sinus com- 

 municating above the atlas with the posterior spinal plexus ; 15, external jugular vein. 



