236 THE ESSENTIALS OF HISTOLOGY 



The cochlea consists of a bony tube coiled spirally around an axis, 

 which is known as the columella (fig. 275). The tube is divided 

 longitudinally by a partition which is formed partly by a projecting 



FIG. 275. VERTICAL SECTION OF THE COCHLEA OF A CALF. 



S.V 



sp.l 



FIG. 276. VERTICAL SECTION OF THE FIRST TURN OF THE HUMAN COCHLEA. 



(Retzius.) 



.r. scala vestibuli ; s.t. scala tympani ; D.C. canal of the cochlea; sp.l. spiral lamina; n, 

 nerve-fibres ; l.sp. spiral ligament ; str.v. stria vascularis ; s.sp. spiral groove ; R, section of 

 Eeissner's membrane; /, limbus laminae spiralis ; M.I. membrana teetoria ; t.C. tunnel of 

 Corti ; b.m. basilar membrane ; h.i., h.e., internal and external hair-cells. 



lamina of bone (spiral lamina], partly by a flat membrane (basilar 

 membrane), into two parts or scala ; the upper (supposing the cochlea 

 resting base down wards) being termed the scala vestibuli (fig. 27C, s.v.) 



