864 HUMAN ANATOMY. 



lingual or superior thyroid vein. They take their origin from a venous plexus 

 (plexus pharyngeus) which covers the outer surface of the pharynx, lying between 

 the constrictor muscles and the pharyngeal portion of the bucco-pharyngeal fascia. 

 In addition to branches from the pharyngeal wall, this plexus also receives tributaries 

 from the anterior recti and longus colli muscles, and from the soft palate, the tonsillar 

 plexus and the Eustachian tube, and has opening into it branches from a plexus which 

 surrounds the internal carotid artery in its course through the carotid canal, communi- 

 cating above with the cavernous sinus. It also receives the veins (vv. canalis pterygoidei) 

 which accompany the Vidian artery through its canal, and communicates with the 

 pterygoid, oesophageal, and vertebral plexuses. 



2. The Facial Vein. — The facial vein (v. facialis anterior) (Fig. 754) is 

 formed at about the inner extremity of the eyebrow by the union of the frontal and 

 supraorbital veins. From its point of origin it skirts around the inner border of the 

 orbit and is then directed obliquely downward and backward across the face, crosses 

 over the anterior inferior angle of the masseter muscle and the ramus of the mandible 

 a short distance in front of the angle, and is thence continued onward across the 

 posterior part of the submaxillary and the upper part of the superior carotid triangles 

 to open into the internal jugular at about the level of the hyoid bone. It follows 

 in a general way the course of the corresponding artery, lying posterior to it, but 

 the path across the face is much more direct than that followed by the artery. 



That portion of the vein which extends from the junction of the frontal and supra- 

 orbital arteries to the lower border of the orbit is usually termed the angular vein, 

 and branches arise from this which pass backward into the orbit to communicate 

 with the ophthalmic vein. Just below the ramus of the mandible it usually receives 

 a large communicating branch from the external jugular, and the portion which in- 

 tervenes between this communication and the internal jugular is termed the common 

 facial vein (v. facialis communis). Both the facial and the angular veins are usually 

 described as being destitute of valves ; these structures do occur, however, but they 

 are always insufficient and form no bar to the passage of blood in an inverse direc- 

 tion — i.e., from the facial and angular backward into the ophthalmic veins. 



Relations. — The angular vein rests upon the nasal process of the maxillary 

 vein internal to the lachrymal sac. In its upper portion the facial vein lies under 

 cover of the orbicularis palpebrarum, and it also passes beneath the zygomatic muscles, 

 but is superficial to the other muscles of the face. In its inframandibular or cervical 

 portion it lies beneath the platysma in a groove in the submaxillary gland. 



Variations.— The upper portion of the facial vein may be greatly reduced in size. Below, 

 it frequently unites with the lingual vein to form a linguo-facial trunk, which may also be joined 

 by the superior thyroid. Instead of opening into the internal jugular, it occasionally passes 

 across the stemo-cleido-mastoid muscle to unite with the external or anterior jugular. 



Practical Considerations. — Allen has called attention to the fact that the 

 venous supply of the face differs in some important particulars from that of the trunk 

 and limbs. In the last-named localities, both deep and superficial currents flow in 

 the same direction towards the heart. The facial trunk, however, is not formed by 

 primal venules, as is commonly the case, but by branches communicating with the 

 frontal and supraorbital veins, and by a transverse branch found at the bridge of 

 the nose. 



The two most important communications with the cavernous sinus are through 

 the ophthalmic vein, which receives tributaries from the angular vein, and the deep 

 facial vein, which empties into the pterygoid plexus, which in its turn communicates 

 with the cavernous sinus by veins passing through the foramen ovale. The veins 

 corresponding to the deep parts of the face, other than those mentioned, also seek 

 an outlet in the same direction, so that much of the superficial blood of the upper 

 part and side of the face passes imvard to the brain-case and to the interior of the 

 facial region, while the remaining portion flows downward to join the jugular veins. 



The facial vein at its lower end receives a large communicating branch from the 

 external jugular, and therefore at or below that point carries a considerable volume 

 of blood, making wounds of the vein dangerous. 



