THE MEMBRANOUS LABYRINTH 



1093 



membranes are in contact, however, with the bony wall along their convex margin, 

 and the utricle, saccule and cochlear canals are in contact with the bony walls 

 over the areas where the nerves enter them. The fluid which fills the mem- 

 branous labyrinth is termed the endolymph. 



Fig. 836. — The Osseous Labyrinth of the Right Side. 

 (Modified from Soemmerring. Enlarged.) 

 Superior semicircular canal - 



Posterior semicircular canal 



Lateral semicircular canal 



Vestibule and fenestra ovalis' 



Ampulla 

 Ampulla 



Second turn of cochlea 

 Cupula of cochlea 



Ampulla 

 Fenestra cochlearis 

 Commencement of first turn of the cochlea 



The utricle is an oval tubular sac, whose rounded end lies in the superior and 

 dorsal portion of the vestibule. It is here tightly bound to the elliptic recess 

 (fovea hemielliptica) by connective tissue and by the entrance of the filaments 

 of the utricular division of the vestibular nerve as they pass from the superior 



Fig. 837. — Interior of the Osseous Labyrinth of the Left Side. 

 (Modified from Soemmerring. Enlarged.) 



Superior semicircular canal 



ElKptic recess (fovea 

 hemielliptica) 



Superficial recess (fovea 

 hemispherica 



Lamina spiralis' 

 Scala tympani of cochlea' 



Posterior semicircular canal 



Lateral semicircular canal 

 Opening common to superior and 



posterior semicircular canal 

 Internal aperture of vestibular 

 aquaeduct 



Internal aperture of cochlear 

 canaliculus 



macula cribrosa to the wall of the utricle. In the anterior part of the interior of 

 the utricle, an oval, whitish, thickened area, macula acustica utriculi, marks the 

 terminal distribution of the nerve, and posteriorly the utricle is joined by the 

 orifices of the semicircular ducts. 



Fig. 838. — Interior of the Osseous Cochlea, (Enlarged.) 



Scala vesfibull 

 Scala tympani 



Lamina spiralis 

 Modiolus 



The saccule is a flattened, oval sac, smaller than the utricle, and situated in 

 the anterior and inferior part of the vestibule. It is bound to the spherical recess 

 (fovea hemisphserica) by connective tissue and by the saccular division of the 



