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AN AMERICAN TEXT-BOOK OF PHYSIOLOGY 



of simple character supported upon the basilar membrane, and rapidly decreas- 

 ing in heighl externally into a layer of cuboidal epithelium covering the outer 

 part of the basilar membrane. The rods of < lorti arc peculiarly shaped at the 

 top, the upper extremity of each being bent at an angle so as to project exter- 

 nally and parallel with the basilar membrane; these projections are the pha- 

 la/ngar processes of the rods, the phalanges of the inner row overlapping those 

 of the outer row. These phalangar processes of the rods form the points of 

 attachment — in fact, the beginning — of the reticulate membrane (inembrana 

 reticulata), a peculiar cuticular, network-like structure formed of rings and 

 cross-bars, having the appearance of certain vegetable tissues seen under the 

 microscope. The reticulate membrane stretches across the outer rows of hair- 



1,1 j 





n.aud l.l i.spn t.xjiit o.spn c i> 



lg.sp 



Fig. 194.— Diagram of the organ of Corti (from Foster, after Retzius) : i.r, inner rod of Corti; o.r, outer 

 rod of Corti; i.fte, inner hair-cell ; v.c, the group of nuclei beneath it; o.hc, outer hair-cells, or cells of 

 Corti; C.I), the twin cells of Deiters (four rows) ; n.aud, the auditory nerve perforating the tympanic lip, 

 l.l. and lost to view among the nuclei beneath the inner hair-cells: i.spn, the inner spiral strand <>f nerve- 

 fibrils; t.spn, the spiral strand of the tunnel: o.spn, the outer spiral strand belonging to the tirst row of 

 outer hair-cells ; the three succeeding spiral strands belonging to the three other rows are also shown ; 

 nerve-fibrils are shown stretching radially across the tunnel^ //.<■, Etensen's cells; Cl.c, Claudius' cells; 

 t.i. lymphatic epithelioid lining on the side toward the Bcala tympani : lg.sp, Ugamentum spirale; c, cells 

 lining the spiral groove, overhung by the vestibular lip,l.v; m.t, tectorial membrane; a fragment, torn 

 from it, remains attached to the organ of Corti just outside the outermost row of hair-cells. 



cells, the body <>f each of which is enclosed and is held at its top within a ring 

 of the network (Fig. 195, d). 



Each of the cells of Deiters, described above, is continued upward in a 

 process which is attached to a cross-bar or a ring of the reticulate membrane 

 next outside its companion-cell of Corti. The inner or median line of the 

 Deiters cell is also modified into a cuticular thread fused below to the basilar 

 membrane and above to a ring of the reticulate membrane. Thus the audi- 

 tory hair-cells of Corti may be regarded as suspended from the reticulate mem- 

 brane, which in turn is supported by the cuticular processes of the cells of 

 Deiters. which rest upon the basilar membrane, and by the phalangar pro- 

 cesses of the rods of Corti. The physical contacl of the cells of Corti with 

 those of Deiters is so intimat< — if, indeed, their substance is not continuous — 

 that impulses generated in the one can probably easily be communicated to 

 the other. 



The upper wall of the canalis cochlearis is made of a sheet of homogenous, 

 fibrillated connective tissue covered with Hat cells, and stretches from the 

 limbus of the spiral lamina outward and upward to the side wall of the 



