THE INTERNAL JUGULAR VEIN 659 



into the muscular veins returning the blood from the four recti. They form a circumcorneal 

 ring of episcleral veins [\-v. episclerales]. The posterior set, which drain the venae vorticosae, 

 leave the globe midway between the cornea and the entrance of the optic nerve. The latter 

 veins are four or five in number, the upper ending in the superior, the lower in the inferior 

 ophthalmic vein (fig. 520). 



(5) The anterior and posterior ethmoidal veins [vv. ethmoidales ant. et post.), correspond 

 in their course with the arteries of the same name. They enter the orbit through the anterior 

 and posterior ethmoidal foramina, and join either the ophthalmic direct, or one or other of 

 the superior muscular branches. 



(6) The lacrimal vein [v. lacrimahs] returns the blood from the lacrimal gland, and corre- 

 sponds in its course to the lacrimal artery. 



(7) The central vein of the retina [v. centrahs retinae] runs with the central artery in the 

 optic nerve. It joins the superior ophthalmic at the back of the orbit. 



(8) The inferior ophthalmic vein [v. ophthalmica inferior], smaller than the superior, is 

 formed near the front of the orbit by the confluence of the inferior muscular with the lower 

 posterior ciliary veins. It runs backward below the optic nerve, along the floor of the orbit, 

 and either joins the superior ophthalmic vein, or opens separately into the cavernous sinus. 

 A large communicating branch passes downward through the inferior orbital (spheno-maxiUary) 

 fissure to join the pterygoid plexus of veins. It receives muscular twigs from the inferior and 

 lateral rectus and from the inferior oblique, and some posteior ciliary veins. 



7. THE VEINS OF THE PHARYNX AND LARYNX 



The pharyngeal veins [vv. pharyngese] are arranged in the form of a plexus, 

 between the constrictor muscles and the pharyngeal or prevertebral fascia. The 

 pharyngeal plexus receives branches from the mucous membrane, the pterygoid 

 canal [vv. canalis pterygoidei] from the soft palate, the Eustachian tube and the 

 anterior recti and longus colli muscles. Above, it communicates with the ptery- 

 goid plexus of veins; below it drains into the internal jugular vein. 



The veins of the larynx end partly in the superior laryngeal vein [v. laryngea 

 superior], which opens into the internal jugular vein, and partly in the inferior 

 laryngeal vein [v. laryngea inferior], which terminates in the plexus thyroideus 

 impar. The laryngeal plexus of veins communicates with the pharyngeal plexus. 



8. THE DEEP VEINS OF THE NECK 



The deep veins of the neck include the internal jugular, vertebral, deep cervical, 

 erior thyreoid, thyreoidea ima, thymic, tracheal, and oesophageal veins. 



The Internal Jugular Vein 



The internal jugular vein [v. jugularis interna] begins at the jugular fossa, and 

 is the continuation of the transverse sinus. It passes down the neck, in company 

 first with the internal carotid artery and then with the common carotid artery, 

 to a point a little lateral to the sterno-clavicular articulation, where it joins the 

 subclavian to form the innominate vein. At its commencement in the larger, 

 posterior and lateral part of the jugular foramen, it is somewhat dilated, forming 

 the superior bulb of the jugular vein [bulbus v. jugularis superior] (fig. 522). 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 vagus nerves, and by the carotid plexus of the sympathetic. 

 As it descends it passes gradually to the lateral side of the internal carotid, and re- 

 tains this relation as far as the upper border of the thyreoid cartilage. Thence it 

 runs to its termination along the lateral side of the common carotid artery, being 

 contained in the same sheath with it and the vagus nerve, but separated from 

 these structures by a distinct septum. The vein generally overlaps the artery in 

 front. About 2.5 cm. (1 in.) above its termination it contains a pair of imperfect 

 valves below which a second dilation usually occurs in the vein. This, the inferior 

 bulb [bulbus v. jugularis inferior], extends as low as the junction of the internal 

 jugular with the subclavian. It not infrequently receives the termination of the 

 external jugular vein. 



Tributaries. — At the superior bulb the internal jugular vein receives the 

 inferior petrosal sinus; the vein of the cochlear canaliculus, and a meningeal 



