636 



THE EAR 



a more scanty network in the remaining portions of the membran- 

 ous labyrinth. 



The cochlear division of the internal auditory artery, according 

 to Siebenmann, promptly subdivides into the cochlear artery 



d 



f 



FIG. 460. SCHEME OF THE VASCULAR SUPPLY OF THE INTERNAL EAR. 

 <7i, first turn of the cochlea; /S, saccule; Sup. S.C., Ext. S.C., and Post. S.C., superior, 

 external, and posterior semicircular canals ; 7", utricle. The arteries are in heavy black, 

 the veins somewhat lighter : a, central vein, and &, central artery of the cochlea ; c, ves- 

 tibular artery; rf, vestibulo-cochlear artery; 0, arteria proprise cochleae; /, vena aque- 

 ductus cochlese ; g, vena aqueductus vestibuli. 



proper, which appears as the continuation of the vessel, and the 

 vestibulo-cochlear artery, which supplies the macula sacculi, the 

 posterior ampulla, and the adjacent portions of the utricle and 

 posterior semicircular canal. This vessel also supplies the early 

 portion of the first turn of the spiral cochlea. 



The true cochlear artery enters the modiolus and supplies a 

 branch to the remaining portion of the first cochlear turn, and a 

 terminal branch which passes as far as the apex of the cochlea, 

 distributing its branches to the last two turns. All of these vessels 

 are characterized by their peculiarly tortuous course. They dis- 



