VEINS OF ORBIT, NOSE, AND PTERYGO-MAXILLARY REGION. 835 
Veins of the Orbit.—The veins of the orbit correspond, with the exception of 
the frontal vein, with the branches of the ophthalmic artery, and they gradually 
converge, as they pass backwards in the orbit, until they form two main trunks, an 
upper (v. ophthalmica superior) and a lower (vy. ophthalmica inferior); these 
terminate, separately or by a single trunk, in the anterior end of the cavernous 
sinus, to which they pass through the foramen lacerum anterius, and between the 
two heads of the external rectus muscle. 
The superior ophthalmic vein communicates, at the internal angle of the orbit, 
with the angular vein, and the inferior ophthalmic vein communicates through the 
spheno-maxillary fissure with the pterygoid plexus. i 
Veins of the Nose.—The veins of the walls of the nasal cavity end partly in 
the ethmoidal tributaries of the superior ophthalmic vein, partly in the septal 
affluent of the superior coronary and in the lateral nasal veins, both of which are 
tributaries of the facial vein; but the majority of the veins of the nose, both from 
the septal and outer walls, join together to form a spheno-palatine vein which 
passes through the spheno-palatine foramen and the spheno-maxillary fossa, and 
terminates in the pterygoid plexus. 
Pterygoid Plexus and the Internal Maxillary Vein.—The pterygoid plexus 
(plexus pterygoideus) of veins lies in the zygomatic and pterygoid fossw. It covers 
the inner surface of the internal pterygoid muscle, and surrounds the external 
pterygoid. It receives tributaries which correspond with and accompany the 
branches of the internal maxillary artery—viz. spheno-palatine, pterygo-palatine, 
vidian, infraorbital, posterior superior dental, posterior palatine, buccal, two or three 
deep temporal, pterygoid, masseteric, and inferior dental veins, and the vena 
comites of the middle meningeal artery. It communicates superiorly with the 
cavernous sinus through the foramen ovale, anteriorly with the inferior ophthalmic 
vein through the spheno- maxillary fissure, and between the masseter and the 
buccinator with the facial vein by the deep facial anastomosing branch. It also 
communicates posteriorly and internally, on the inner side of the internal pterygoid, 
with the pharyngeal plexus, and it terminates posteriorly in the internal maxillary 
vein. 
The internal maxillary vein is a short vessel which accompanies the first part of 
the internal maxillary artery, between the spheno-mandibular ligament and the 
neck of the lower jaw; it enters the parotid gland, and terminates by uniting with 
the superficial temporal vein to form the temporo-maxillary trunk. Occasionally 
the internal maxillary vein is double. 
The temporo-maxillary vein (v. facialis posterior) is a short trunk which is 
formed in the upper part of the parotid gland, behind the neck of the jaw, 
by the union of the superficial temporal and internal maxillary veins. As it 
descends it lies superficial to the external carotid artery, and it is crossed by the 
cervico- and temporo-facial branches of the facial nerve. It terminates at the 
lower part of the parotid gland by dividing into posterior and anterior divisions. 
The posterior division passes backwards, perforates the deep cervical fascia, and 
unites on the upper part of the sterno-mastoid muscle with the posterior auricular 
vein to form the external jugular vein. The anterior division passes downwards 
and forwards into the carotid triangle, where it terminates in the common facial 
vein. 
VENOUS SINUSES AND VEINS OF THE CRANIUM, AND OF ITS 
CONTENTS. 
The venous channels met with in the cranial walls and cranial cavity are :— 
(1) The diploic veins (vv. diploice), which le in the cancellous tissue between 
the outer and inner tables of the cranial bones. 
(2) The meningeal veins, which accompany the meningeal arteries in the outer 
layer of the dura mater. 
(3) The veins of the brain, which le between the folds of pia mater and in the 
subarachnoid space. 
(4) The eranial venous sinuses, channels which are situated between the outer 
