BLOOD SUPPLY 



637 



tribute terminal branches to the limbus spiralis and to the con- 

 nective tissue of the membranous scala vestibuli, extending as far 

 around this canal as the spiral ligament. No vessels cross in the 

 basal membrane. 



The veins collect the blood from the liinbus spiralis and the 

 wall of the scala tympani and form venous trunks within the 

 modiolus, which correspond more or less closely with the arteries. 

 Those veins coming from the wall of the scala tympani unite to 

 form anterior and posterior spiral veins in the limbus and inner 

 wall of the scala tympani. These vessels chiefly empty into the 

 vena aqueductus cochleae which finds its way through the aqueduct 

 to the internal jugular vein. Other branches from the interior of 

 the cochlea unite to form the central vein of the cochlea, which 



FIG. 461. SCHEME OF THE VASCULAK TERMINATIONS IN THE WALL OF THE COCHLEAB 



CANALS. 



<?, capillary vessels in the spiral ligament; DC, cochlear duct or scala media; rf, 

 capillaries in the limbus spiralis ;/, scala tympani ; <?, arteriole ; A, spiral ganglion ; i, 

 venule; 0, scala vestibuli. (After Bohm and von Davidoff.) 



becomes the chief radical of the internal auditory vein, and thus 

 enters either the transverse or inferior petrosal sinus. 



The veins from the utricle and semicircular canals mostly enter 

 the vena aqueductus vestibuli, which follows its aqueduct to the 

 superior petrosal sinus. 



It will be perceived that the blood has three chief avenues of 

 exit from the labyrinth : 1, by the vena aqueductus vestibuli ; 2, 



