THE INTEENAL MAXILLARY VEIN. 477 



substance of the parotid gland as it descends behind the ramus of the 

 jaw. Beneath the angle of that bone, it divides into two vessels, one 

 of which turns backwards, and forms the commencement of the external 

 jugular vein, while the other communicates with the facial vein near 

 its termination. 



Tributaries. — These are numerous : — (r?) imrot'ul branches from the parotid 

 gland ; (Jj) articular, from the articulation of the jaw ; (c) anterior auricular 

 veins from the external ear ; {d) the tran.'<vcrsr, facial, a branch of consider- 

 able size, corresponding Tvith the transverse facial artery ; (s) the jw-stcrior 

 auricular directed forwards from behind, and joined by the stylo-mastoid vein ; 

 and (/) the internal maxillartj vein, a large vessel, which requires more par- 

 ticular description. 



The internal maxillary vein corresponds somewhat in direction, 

 and position with the artery of the same name, and receives branches 

 from the neighbouring parts, most of which are the venie comites of 

 the corresponding divisions of the internal maxillary artery. Thus 

 three or four deep temporal branches descend from the temporal muscle ; 

 others come fi'om the pterygoid, masseter, and buccinator muscles. 

 The middle meningeal veins and some palatine veins also end in the 

 internal maxillary ; and lastly, branches from the surface of the upper 

 jaw — superior dental, and another, of large size, from the lower jaw, 

 emerging from the dental foramen — inferior dental. These different 

 branches form a plexus of veins, named jj/fr?///OM?ji;/ex'i<s, which is placed 

 in the lower part of the temporal fossa, between the temporal and the 

 external pterygoid muscle, and in part between the pterygoid muscles. 

 It communicates in front with the facial vein, and above, with the 

 cavernous sinus by branches through the base of the skull. From this 

 plexus proceed one or two short trunks, which join nearly at right 

 angles with the temporal vein. 



The facial commumcatinr/ vein, extending between the temporal vein at the 

 angle of the jaw and the facial vein, a little in front of it. is a short trunk, 

 usually the larger of the two into which the temporal vein divides, and placed 

 nearly transversely, so as to allow the iiow of blood either from the temporal 

 into the internal jugular vein, or from the facial into the external jugular. 



External Jugular Vein. — This vein commences on a level with 

 the angle of the lower maxilla, at the end of the temporal vein, and 

 descends perpendicularly between the platysma and fascia, crossing the 

 sterno-mastoid muscle. In consequence of the oblique direction of that 

 muscle, the vein gets to its outer border, and continues behind it down 

 to the lower part of the neck, where it pierces the fascia to terminate 

 either as a single trunk, or by two or three branches in the subclavian 

 vein. It is provided with a valve at its lower end, and in most cases 

 with another about the middle of its course. 



Tributaries. — The external jugTilar vein receives some large branches from 

 behind, and superficial branches from the fore part of the neck. The largest 

 branches are the following. 



(fl) The posterior branch, lying at first between the splenius and trapezius 

 muscles, passes down at the outside of the jugular vein, and below the middle of 

 the neck opens into that vessel. 



(b) The suprascapular and posterior scapular veins, con-esponding to the 

 arteries of the same name, pass transversely inwards to join the external jugular 

 vein close to its termination. 



