Quain's elements of anatomy . before stated, the liquid contained within themembranous labyrinth is distinguished as endolymph. The cavity which contains the perilymph communicates throtigh the sheath ofthe auditory nerve with both the subdui-al and subarachnoid spaces. Vestibule.—Within the osseous vestibule are two membranous sacs, VOL. II. G G 450 THE EAE. the one of which, termed the utricle, is connected with the semicircularcanals, whilst the other, the saccule, is connected with the cochlea. Thesetwo sacs although in close contact do not open directly into one anotheralthough they are i
Quain's elements of anatomy . before stated, the liquid contained within themembranous labyrinth is distinguished as endolymph. The cavity which contains the perilymph communicates throtigh the sheath ofthe auditory nerve with both the subdui-al and subarachnoid spaces. Vestibule.—Within the osseous vestibule are two membranous sacs, VOL. II. G G 450 THE EAE. the one of which, termed the utricle, is connected with the semicircularcanals, whilst the other, the saccule, is connected with the cochlea. Thesetwo sacs although in close contact do not open directly into one anotheralthough they are in indirect communication, in a mamier presently tobe explained. The larger of the two sacs, the common sinus or utricle (fig. 390, ii),is of an oblong form, slightly flattened from without inwards. It islodged in the upper and back part of the yestibule, occupying the foveahemi-elliptica and the space immediately below this. Opposite the cristavestibuli several small branches of the auditory nerve enter from the Fis;. jj}^.c. Fig. 390.—Plan of the right mem- BRAKOtJS LABYRINTH VIEWED FROIITHE MESIAL ASPECT () 2^. ^l, utricle, with its macula and tliethree semicircular canals with theirampullar; s, saccule; aq. v. aquedactusvestibuli; s. e. saccus endolymphati-cus ; c. r. canalis reuniens; c. c. canalof the cochlea. foramina in the bone; and herethe walls of the common sinusare thicker and more opaque than elsewhere {macvla acustica). A small mass of calcareous particles (otoliths or otoconia) lies within the sac, attached to its walls at this place. These otoliths are crystals of carbonate of lune, rhombic, octahedral, or six-sided, often pointed at their extremities. The ends of all the membranous semicircular canals open into the utricle. The small vestibular vesicle, the saccule (fig. 390, s), is more nearly spherical than the common sinus, but, like it, is somewhat flattened. The saccule is situated in the lower and fore part of the cavity of the osseous Tm.
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