418 ANATOMY FOR NURSES [Chap. XX 



places it is attached to the bone by bands of fibrous tissue. The 

 cavity within the membrane is filled with a fluid called endolymph, 

 and the space between the membrane and the bone is filled with 

 perilymph. 



The vestibule is the central cavity situated between the cochlea 

 in front and the semicircular canals behind. It communicates 

 with the middle ear by means of the oval window in its outer wall. 

 The vestibular membrane is constricted in the centre so that it 



Fig. 196. — The Left Bony Labyhinth of a New-born Child, Forward and 

 Outward View, X 4. From a photograph, and slightly reduced. 



1, the wide canal, the beginning of the spiral canal of the cochlea ; 2, the fenestra 

 rotunda; 3, the second turn of the cochlea; 4, the final half-turn of the cochlea; 

 5, the border of the bony wall of the vestibule, situated between the cochlea and 

 the semicircular canals ; 6, the superior, or sagittal semicircular canal ; 7, the 

 portion of the semicircular canal bent outward ; 8, the posterior, or transverse 

 semicircular canal ; 9, the portion of the posterior connected with the superior semi- 

 circular canal ; 10, point of junction of the superior and the posterior semicircular 

 canals ; 11, the ampulla ossea externa ; 12, the horizontal, or external semicircular 

 canal. (Flint.) 



consists of two small sacs, called respectively the saccule and the 

 utricle. The saccule is in front and nearer the cochlea, and the 

 utricle is back and nearer the semicircular canals. These sacs 

 are connected by a tube called the endolymj)h duct, which is 

 shaped like an inverted Y (X). The walls of these sacs contain 

 numerous columnar cells provided with stiff hairs which project 

 into the endol\-mph. These cells are in relation with fibres of the 

 vestibular branch of the auditory nerve and serve as end organs. 

 Among these hair-cells rest several small crystals of calcium car- 

 bonate which are called otoliths. 



