776 



THE SENSE OF HEARING 



mentous tissue upon the external wall of the cochlear canal. Retzius 1 

 has estimated the number of these fibers at 24,000. 



The entire cochlear canal is lined by a single layer of cuboidal 

 cells which also extend across the under surface of the membrane of 

 Reissner. The body of the latter consists of an extremely thin layer 

 of connective tissue derived from the periosteal lining of the scala 

 vestibuli. 2 It is to be noted especially that the cells situated upon 

 the basilar membrane, possess a most peculiar appearance. A single 

 cross-section of this particular area presents two rod-shaped cells 



FIG. 394, DIAGRAMMATIC VIEW OF THE ORGAN OF CORTI, THE SENSE CELLS, AND THE 



ACCESSORY STRUCTURES OF THE MEMBRANOUS COCHLEA. 



A, inner rods of Corti; B, outer rods of Corti; C, tunnel of Corti; D, basilar mem- 

 brane; E, single row of inner hair (sense) cells; 6, 6', 6", rows of outer hair (sense) cells; 

 7, 7', supporting cells of Deiters. The ends of the inner hair cells are seen projecting 

 through the openings of the reticulate membrane. The terminal arborizations of the 

 cochlea nerve fibers end around the inner and outer hair cells. (Testut.) 



which are separated at their bases, but come together above in the 

 manner of the sides of a roof. These cells are usually referred to as 

 the inner and outer rods of Corti. The triangular space situated in 

 between this double row of inclined cells, is known as the tunnel of 

 Corti. Internal to the inner rod of Corti is a single epithelial cell 

 which sends a brush of short and stiff projections into the endolymph. 

 On the outer side of the outer rod of Corti are three or four cells which 

 are slender in shape and also carry hair-like processes. 3 They are 

 supported by the so-called cells of Deiters. External to these hair 



1 Das Gehororgan der Wirbeltiere, ii, 1884. 



2 Stohr, Anat. Anzeiger, 1907, und Kolmer, Archiv fur mikr. Anatomie, Ixx, 

 1907. 



3 Scott, Jour, of Anat. und Physiol., 1909, also see: Nakamura, tlber die Myeli- 

 noid-Substanz in den Haarzellen des Cortischen Organes, Berlin, 1914. 



