THE INTERNAL EAR 



715 



artery, which supplies the macula sacculi, the posterior ampulla, and the 

 adjacent portions of the utricle and posterior semicircular canat. "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 



FIG. 591. SCHEME OF THE VASCULAR TERMINATIONS IN THE WALL OF THE COCH- 

 LEAR CANALS. 



c, capillary vessels in the spiral ligament; DC, cochlear duct or scala media; d, 

 capillaries in the limbus spiralis; /, scala tympani; g, arteriole; h t spiral ganglion; 

 i, vena spiralis inferior; v, scala vestibuli; j, vena spiralis superior. (After Bohm 

 and von Davidoff.) 



branches to the last two turns. All of these vessels are characterized 

 by their peculiarly tortuous course. They distribute terminal branches 

 to the limbus spiralis and to the connective tissue of the membranous 

 scala vestibuli, extending as far around this canal as the spiral ligament. 

 No vessels cross in the basilar membrane. 



The veins collect the blood from the limbus spiralis and the wall of 

 the scala tympani and form venous trunks within the modiolus, which 

 correspond more or less closely with the arteries. Two of the cochlear 

 radicals of the venous tributaries are important by reason of their posi- 

 tion and relative size: the vas prominens of the prominentia spiralis of 

 the stria vascularis, and the vas spiralis beneath the organ of Corti. 



