62G 



THE VEINS 



ticosae, which leave the gloVje midway between the cornea and entrance of the optic 

 nerve. The latter veins are four or five in number, the upper ending in the sujje- 

 rior, the lower in the inferior ophtlialmic vein (page 852). 



(3) The anterior and posterior ethmoidal veins corresijond in their course 

 with the arteries of the same namr. They enter the orbit through the anterior and 

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

 of the superior muscuhir l)ranches. 



(4) The lachrymal vein returns the l)lood from the lachrymal gland, and corre- 

 sponds in its course to the lachrymal artery. 



(5) The central vein of the retina runs with the central artery in the optic 

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



Fiu. 389. — The Veins of the Orbit. 



Supraorbital arlerij 



LACHRYMAL GLAND 

 Superior rectus, cut 



EYEBALL 



External rectus A. 



Lachrymal artery 



Superior rectus, cut 

 Inferior ophthalmic vein 

 Siiperior ophthalmic vein 



OPTIC NERVE 



Common ophthalmic vein 



Commencement of superior 

 ojihthaimic vein 



Reflected tendon of superior 



oblique 

 Ophthalmic artery 



Anterior ethmoidal artery 



Posterior ethmoidal artery 

 Cilian/ arteries 



Levator palpebrae, cut 

 Ligament of Zinn 

 Ophthalmic artery 



OPTIC COMMISSURE 



Internal carotid artery 



B. The inferior ophthalmic vein, smaller than the superior, is formed near the 

 front of the orbit l)y the confluence of the inferior muscular with the lower posterior 

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

 and either joins the superior ophthalmic vein to form the common ophthalmic trunk, 

 or else opens separately into the cavernous sinus. A large communicating branch 

 passes downwards through the spheno-maxillarv fissure to join the pterygoid plexus 

 of veins. 



Tributaries. — (1) Tlie inferior muscular, wliich are derived from tlie 

 inferior ol>li<iue, inferior rectus, and external rectus; and (2) the lower posterior 

 ciliary veins. 



7. THE VEINS OF THE PHARYNX AND LARYNX 



The veins of the pharynx are arranged in the form of a plexus, between the 

 constrictor muscles and the pharyngeal or prevertebral fascia. The plexus receives 

 branches from the mucous membrane, from the soft palate, the Eustachian tube, 

 and the ante^rior recti and lons;us colli muscles. Above, it comnumicates with the 



