638 THE EAR 



by the vena aqueductus cochleae ; and, 3, by the internal auditory 

 vein. The greater portion of the blood pursues the second course 

 and thus finds its way to the internal jugular vein, the smaller 

 remainder entering the petrosal sinuses by one of the other two 

 avenues. 



LYMPHATICS. The internal ear contains relatively few lym- 

 phatic vessels but is richly supplied with broad lymphatic spaces. 

 Anastomosing vessels are found in the periosteum and membranous 

 wall of the labyrinth. These communicate with the perilymph 

 spaces between the periosteum and the membranous wall in the vesti- 

 bule, and with the vestibular and tympanic scalae in the cochlea. 

 The perilymphatic spaces are connected with the subdural space of 

 the meninges by means of lymphatic vessels in the aqueductus 

 cochleae. The perilymph of the vestibule also communicates with 

 the subdural space through vessels which follow the sheaths of 

 the nerves. 



The endolymph cavities of the several divisions of the mem- 

 branous labyrinth communicate freely with one another ; by means 

 of the ductus endolymphaticus a connection is also established 

 through the aqueductus vestibuli with the subdural space, the 

 blind terminal saccule of this canal, the saccus endolymphaticus , 

 lying upon the posterior surface of the petrous bone and in contact 

 with the dura mater. 



