324 THE CIRCULATORY SYSTEM. 



maxillary gland (ii) to join the anterior facial (c) caudad of the 

 angle of the jaw. 



As it passes ventrad of the parotid gland (lo), just before 

 becoming superficial, the posterior facial receives the super- 

 ficial temporal (;//). This at first follows the superficial tem- 

 poral artery (s), then enters the substance of the parotid gland, 

 joining the posterior facial near the ventral border of the latter. 

 The superficial temporal receives the anterior auricular (u), a 

 large vein passing along the cranial border of the auricular 

 opening and arising dorsad of the eye. 



The posterior facial receives also, at the point where it 

 passes from beneath the parotid gland, the posterior auricular 

 or great auricular vein (/). This collects blood from the back 

 of the head and the external ear, its branches following those 

 of the artery of the same name. It passes along the caudal 

 border of the parotid gland to join the posterior facial. 



Veins of the Brain and Spinal Cord, — The veins of 

 the brain form a large number of small vessels which pour their 

 blood into larger veins lying in folds of the dura mater; these 

 are known as the venous sinuses of the dura mater. These 

 sinuses communicate with the venous plexus about the orbital 

 fissure, coming from the posterior facial vein ; with the internal 

 jugular through the jugular foramen, and with the vertebral 

 veins, in the vertebral canal. The chief sinuses of the dura 

 mater on the dorsal side of the brain are as follows: 



1. Sinus sagittalis superior. — This lies in the dorsal part 

 of the falx cerebri, between the two hemispheres of the cere- 

 brum. It receives veins from the dorsal and middle parts of 

 the cerebrum, and passes caudad to the tentorium. Here it 

 enters the sinus transversus. It receives the vena cerebri 

 magna, a large vein coming from the interior of the brain and 

 passing directly dorsad at the caudal end of the corpus callosum 

 to enter the sinus sagittalis. 



2. Sinus transversus. — This lies in a canal in the dorsal 

 border of the tentorium. It receives numerous small veins 

 from the cerebellum, roof of the skull, etc. One or two centi- 

 meters on each side of the middle line the sinus transversus 

 passes out of the canal onto the caudal surface of the tentorium, 



