Till-: /.V/'AA'.Y.IA A.I/,' 



10.VJ 



through its anterior medial wall and. wit li 1 lie endolymphat ic duct . connects it with 



i he aMGule. The semicircular ducts (maz&roaone imuetroulw canal-i arc 



uated within 1 he osseou- si -i 1 1 in i-ci liar canals and arc. 1 here fore, known as I lie lateral, 

 superior, anil posterior semicircular duds. They connect witli the utricle by live 

 openings, the posterior and superior ducts unit ins: to form a common crus before 



Fio. 75.5. DIAI.UVM 



no: I. KIT MKMKI: ANOI -. I. \imn\TH. (Deavcr.) 



SUPERIOR AND LATERAL MEMBRANOUS AMPULL* 



SUPERIOR SEMICIRCULAR DUCT 



CUPULAR C/CCUM 



POSTERIOR SEMICIRCULAR DUCT 



COCHLEAR DUCT 



LATERAL SEMICIRCULAR DUCT 

 POSTERIOR MEMBRANOUS AMPULLA 

 DUCTU3 ENDOLUMPHATICUS 



their termination. Each duct is less than a third of the diameter of the bony canal, 

 from which it is separated by a large perilymphatic space, except along the greater 

 curvature, whore it is attached. The duets are dilated in the bony ampulla', pro- 

 ducing the lateral, superior, arid posterior membranous ampullae, and on the 

 attached surface of each of these there isa transverse groove, theampullarysulcus, 



FIG. 756. RIGHT MuMrwAxor* LAIIVKINTII OF A Xr.\vmn\ Cim.n. KXIMISKI> HV I'.vini.u, 

 I! I:\IO\AI, or TIIK UONI ].\i:-,i:i\ni. Dorsal view. (Toldt, "Atlas of Human Anatomy," 

 licliinan, London and Ni'\v Vork.) 



\I:I;\'K 



-. SUPERIOR SEMICIRCULAR DUCT 



t 



h-lOKI- 



\ KK \'K 



MODIOLUS . 



OSSEOUS LAMINA .- 

 SPIRALIS 



LAMINA BASILARIS 

 IMEMSRANOUS 

 LAMINA SPIRALIS) 



SCALA TYHPANI 



SUPERIOR MEMBRANOUS 

 AMPULLA 



COMMON CRUS 



I **'- POSTERIOR SfMICIRCULAR 

 OUCT 



i. 



CANAL 



POSTERIOR MEMBRANOUS AMPULLA 

 POSTERIOR AMPULLARY NERVE 



for the ampullary division of the acoustic nerve, and corresponding to the siilcus 

 a ridiro, the ampullary crista, projects into the interior. The erist:e in the ampulla 



of the membranous semicircular ducts and the macula' in the sacculc and utricle 



are superficially covered with fine crystals of calcium carbonate, otoconia (otoliths). 



The cochlear duct (membranous cochlea or scala media) bedns within the 



