IXTERXAL JUGULAR 627 



pterygoid plexus of veins; below, either with the lower end of the facial vein, or 

 with the intrnial jutrular vein. 



The veins of the larynx end partly in the superior, and partly in the inferior 

 thyroid veins. 



8. THE DEEP VEINS OF THE NECK 



The deep veins of the neck are the internal jugular vein, the vertebral vein, 

 and the deep cervical vein and their respective tributaries. 



The Internal Jugular Vein 



The internal jugular vein begins at the jugular fossa, and is the continuation 

 of the lateral sinus. It passes down the neck in company first Avith the internal 

 carotid artery, and then with the common carotid artery to a spot a little external 

 to the sterno-claAdcular articulation, where it joins the subclavian to form the 

 innominate vein. At its commencement in the larger, and posterior and external 

 part of the jugular foramen, it is somewhat dilated, forming the so-called bulb or 

 sinus of the internal jugular vein. This dilated part of the internal jugular vein 

 lies in the jugular fossa of the temporal bone and is therefore in immediate 

 relation to the floor of the tympanum. At first the internal jugular lies in front 

 of the rectus capitis lateralis, and behind the internal carotid artery, from which it 

 is separated by the hypoglossal, glosso-pharyngeal, and pneumogastric nerves, and 

 by the carotid plexus of the sympathetic. But as it descends it passes gradually 

 to the outer side of that vessel, and retains this relation as far as the upper border 

 of the thyroid cartilage. Thence it runs to its termination along the outer side of 

 the common carotid artery, being contained in the same sheath with it and the 

 pneumogastric nerve, but separated from these structures by a distinct septum. The 

 vein generally overlaps the artery in front; hence the importance in tying the carotid 

 of opening the sheath well to the inner side of that vessel, in order to avoid the 

 vein. About an inch above its termination it contains a pair of imperfect valves. 



Tributaries. — At the bulb or sinus the internal jugular vein receives the 

 inferior jjetrosal sinus; opposite the angle of the jaw veins from the pharyngeal 

 plexus, and often a communicating branch from the external jugular vein; opposite 

 the bifurcation of the carotid it is joined by the facial, and a little lower down by 

 the lingual and the superior thyroid vein, and at the level of the cricoid cartilage 

 by the middle thyroid vein. 



The inferior petrosal sinus is described with the other sinuses of the brain 

 (page 622); the pharyngeal plexus with the veins of the ])harynx (see above); and 

 the facial vein with the superficial veins of the scalp and face (page 613). 



The lingual vein begins near the tip of the tongue, under the name of the 

 ranine. It lies at first close to the hypoglossal nerve and beneath the nmcous 

 membrane covering the under .surface of the tongue. It then passes backwards 

 across the hyo-glossus where this muscle forms the floor of Lesser' s triangle, the 

 latter muscle intervening between it and the lingual artery. After receiving the 

 sublingual vein and the dorsalis lingufe veins which roughly correspond to their 

 respective arteries, and the two small veins (ven* comites) which fre(juently 

 accompany the lingual artery beneath the hyo-glossus, the united trunk crosses the 

 common carotid artery and opens into the internal jugular vein. At times these 

 tributaries open separately into the internal jugular vein or into the facial vein. 



The superior thyroid vein emerges from the upper part of the thyroid body, 

 in Avhich it freely anastomoses with the other thyroid veins, both in the substance 

 of the organ, and on its surface beneath the capsule. Thence it passes upwards 

 and outwards into the internal jugular vein, crossing the common carotid artery in 

 its course. At times it forms a common trunk with the facial vein. Its tribu- 

 taries are the sterno-hyoid, sterno-thyroid, and thyro-hyoid veins from the muscles 

 bearing those names; and the crico-thyroid and superior laryngeal vein, which 

 correspond with the crico-thyroid and superior laryngeal arteries respectively. 

 These require no special description. 



The middle thyroid vein passes out from the capsule of the thyroid gland 



