THE INTERNAL EAR. 



495 



and cristae the capillary networks are numerous and finely meshed, 

 but in the remaining portions of the utriculus, sacculus, and semi- 

 circular canals, they form coarser networks. The cochlear branch 

 accompanies the divisions of the auditory nerve as far as the first 

 spiral turn of the cochlea ; the arteries supplying the remaining 

 turns enter the axis of the modiolus, where they divide into 

 numerous branches. The latter are coiled in a peculiar manner, 

 forming the so-called gloineruli arteriosi cochlea. From these, 

 branches are given off which penetrate the vestibular wall of the 

 lamina spiralis ossea, where they supply the limbus spiralis and the 

 small quantity of connective tissue in the membrana vestibularis. 

 Other branches surround the scala vestibuli, supply the walls of the 

 latter, and then continue to the ligamentum spirale, the stria vascu- 

 laris, and the lamina basilaris. 



g ~~ 



Fig. 376. Scheme of distribution of blood-vessels in labyrinth (after Eichler) : 

 g, Artery ; h, spiral ganglion ; z, vein ; v, scala vestibuli ; DC, ductus cochlearis ; r, cap- 

 illaries in the ligamentum spirale ; d, capillaries in the limbus spiralis ; f, scala tympani. 



The venous trunks lie close to the arteries and receive their 

 blood from the veins which lie at the tympanal surface of the lamina 

 spiralis and from those which encircle the outer wall of the scala 

 tympani. The former, in turn, receive their blood from the capil- 

 laries of the limbus spiralis ; the latter, principally from the region 

 of the ligamentum spirale and the basilar membrane. 



From this description it is seen that the arterial channels are 

 connected with the scala vestibuli, the venous with the scala tym- 

 pani, and that the inner blood stream circulating through the lamina 

 spiralis and limbus spiralis is separated from the blood current of the 

 two scalae, the ligamentum spirale, and the crista basilaris (Eichler). 



The entire membranous labyrinth is filled with endolymph. The 

 ductus endolymphaticus is, as will be remembered, a canal ending 



