644 THE BLOOD-VASCULAR SYSTEM 



angularis]. In the remainder of its course over the face and neck it is termed the 

 anterior facial vein. 



The angular vein skirts around the medial margin of the orbit, lying with the angular 

 artery on the frontal (nasal) process of the maxillary bone slightly medial to the lacrimal 

 sac. Branches pass from the posterior part of the angular vein into the orbit to join the 

 ophthalmic. 



The angular, the facial, and the ophthalmic veins contain no valves. The blood, therefore, 

 can pass either forward from the ophthalmic into the angular, or backward through the facial 

 and angular into the ophthalmic, and so on to the cavernous and other venous sinuses of the 

 cranium. Hence in certain tumom's in the orbit and cranium, the congestion of the angular 

 and facial veins; and the danger in facial carbuncle and anthrax of septic thrombi spreading 

 backward through the angular and ophthalmic veins to the cranial sinuses. 



The anterior facial vein runs in a more or less direct line behind its corre- 

 sponding artery, the external maxillary (facial), which itself pursues a tortuous 

 course. It usually passes deep to the zygomatic muscle, the zygomatic head of the 

 quadratus labii superioris, and the risorius, but superficial to the other muscles. 

 At the anterior edge of the masseter it meets the external maxillary artery, lying 

 immediately posterior to it. In the neck it lies beneath the platysma and cer- 

 vical fascia, and is usually separated from the external maxillary artery by the 

 submaxillary gland and the stylo-hyoid and posterior belly of the digastric muscles, 

 below which it is joined by the posterior facial, to form the common facial vein. 



Tributaries. — It receives, from above downward: — (a) the frontal vein; (b) 

 the supraorbital vein; (c) the superior palpebral veins; (d) the external nasal 

 veins; Ce) the inferior palpebral veins; (f) the superior labial vein; (g) the inferior 

 labial vein; (h) the masseteric veins; (i) the anterior parotid veins; (j) the pala- 

 tine vein and (k) the submental vein. 



(a) The frontal vein [v. frontalis] (fig. 510) begins about the level of the coronal suture in a 

 venous plexus which communicates with the anterior division of the temporal vein. Soon 

 forming a single trunk, it passes vertically downward over the frontal bone, a short distance 

 from the middle line and parallel to its fellow of the opposite side, to the medial end of the eye- 

 brow where it terminates in the angular vein. 



(b) The supraorbital vein [v. supraorbitalis] begins over the frontal eminence by inter- 

 communication with the middle temporal vein. It receives tributaries from the forehead and 

 eyebrow, and, running obliquely, medially and downward, opens into the termination of the 

 frontal vein to form the angular. It communicates with the ophthalmic vein, and receives the 

 frontal vein of the diploe as the latter vein issues from the bone at the bottom of the supraorbital 

 notch. 



(c) The superior palpebral veins [vv. palpebrales superiores] arise in the upper eyeUd and 

 open into the lateral side of the angular vein. They communicate with the middle temporal 

 vein. 



(d) The external nasal veins [vv. nasales externas] form three or four stems on either side. 

 The upper veins rvm upward into the angular and the lower, from the ala, pass more hori- 

 zontally into the anterior facial vein. 



(e) The inferior palpebral veins [vv. palpebrales inferiores] arise in the lower eyelid, and, 

 passing medially and downward over the cheek from which they receive tributaries, open into 

 the lateral side of the anterior facial vein. They coimnunicate with the infraorbital vein. 



(f) Tiie superior labial vein [v. labialis superior] and (g) the inferior labial vein [v. labialis 

 inferior] arise from venous plexuses in the upper and lower lips. They run laterally to open 

 into the medial side of the facial vein. 



(h) The masseteric veins [vv. masseterica;] and (i) the anterior parotid veins [vv. parotidae 

 anteriores], of small size, drain the clieek over the masseteric and parotid regions. 



(j) The palatine vein [v. palatina] accomf)anies the ascending palatine or tonsillar artery 

 from the venous plexus about the tonsil and soft palate, and joins the anterior facial vein just 

 below the body of tlie mandible. 



(k) The submental vein [v. submentalis] lies on the mylo-hyoid muscle superficial to the 

 submental artery. Running back in the submental triaiigle, it joins tlie anterior facial vein 

 just after tlie latter lias passed over the body of the mandible. It communicates with the 

 anterior jugular vein. 



Communications. — ^The tributaries of the anterior facial vein communicate freely with 

 the anterior and middle tf^niporal, <)i)lithahnic, infraorlutal and anterior jugular veins. The; 

 main trunk has a large communicating branch with the pterygoid plexus. This vein, some- 

 times known as the deep facial, opens into the anterior facial Indow the zygomatic bone under 

 cover of the zygomaticus muscle. 



B. The Posterior Facial Vein 



The posterior facial (tomporo-maxillary) vein [v. facialis posterior] is formed in 

 in the region of the root of the zygoma by the union of the superficial and 

 middle temporal veins. It passes downward behind the ramus of the mandible 



