THE INTERNAL EAR, OR LAB YRINTH 



1141 



meatus, where it corresponds with the area cochleae. It is perforated by 

 numerous orifices, which transmit filaments of the cochlear division of the audir 

 lory nerve, the nerves for the first turn and a half being transmitted through the 

 foramina of the tractus spiralis f oraminosus ; those for the apical, turn through the 



CANALIS CANALIS LON- S 



BASIS SP'RALIS GITUDINALIS 

 MODIOLI MODIOLI MODIOLI 



TRACTUS 

 SPIRALIS 



FORAMINOSU 



T BONY 

 NCE OF 



LE OF SULCUS FOR LARGE SUPER- 

 YRINTH /FICIAL PETROSAL NERVE 



LAMINA MODIOLI 



SULCUS FOR SMALL SUPER- 



TEGMEN 

 TYMPANI 



SEMICANAL 



FOR TENSOR 



TYMPANI 



MUSCLE 



GLASCRIAN 



FISSURE 



SEMICANAL OF 



EUSTACHIAN 



TUBE 



CANALIS 

 SPIRALIS 

 MODIOLI 



LAMINA 



SPIRALIS 



OSSEA 



LAMINA SPIRALIS 

 SECUNDARIA 



FIG. 848. Vertical section through the right cochlea, medial portion, viewed from the lateral side. (Spalteholz). 



foramen centrale. The foramina of the tractus spiralis foraminosus pass up 

 through the modiolus and successively bend outward to reach the attached margin 

 of the lamina spiralis ossea. Here they become enlarged, and by their apposition 

 form a spiral canal (canalis spiralis modioli), which follows the course of the attached 



FIG. 849. The cochlea laid open (enlarged). 



margin of the lamina spiralis ossea and lodges the ganglion spirale (of Corti) 

 (ganglion spirale cochleae). The foramen centrale is continued as a canal up the 

 middle of the modiolus to its apex, and from this canal numerous minute foramina 

 pass outward to the unattached edge of the lamina spiralis. In the foramina 

 are vessels and nerves. The modiolus diminishes rapidly in size in the second 

 and succeeding coil. 



