134 HUMAN PHYSIOLOGY 



nearly fills up the bony ampulla, while the canal portion 

 is small, and occupies only a small part of the bony canal. 

 (Fig. 89, p. 165.) 



In the membranous cochlea the lining cells form the organ 

 of Gorti (Fig. 71). This is set upon the basilar membrane, and 

 consists from within, outwards, of 1st, A set of elongated sup- 

 porting cells. 2nd, A row of columnar cells, with short, stiff, 

 hair-like processes projecting from their free border. 3rd, The 

 inner rods of Corti, each of which may be compared to an ulnar 

 bone attached by its terminal end, and fitting on to the heads 

 of the outer rods. 4th, The outer rods of Corti, each resem- 

 bling a swan's head and neck the neck attached to the basi- 

 lar membrane, and the back of the head fitting into the hollow 

 surface of the inner rods. 5th, Several rows of outer hair 

 cells, with some spindle-shaped cells among them. 6th, The 

 outer supporting cells. 7th, Lying over the inner and outer 

 hair cells is the membrana reticularis, resembling a net, 

 through the meshes of which the hairs project. 8th, Arch- 

 ing over this organ is a homogeneous membrane the 

 membrana tectoria. 



The membranous labyrinth is attached to the inner wall 

 of the bony labyrinth at certain points through which fibres 

 of the auditory nerve enter it. A set of fibres goes to the 

 utricle, a set to each of the ampullae, and a set to the 

 saccule and the cochlea. 



The membranous labyrinth has an outer fibrous coat, and 

 inside this a homogeneous layer which is markedly thick- 

 ened where the nerves enter it. It is lined by flattened 

 epithelium, which become columnar, and is covered with 

 stiff hair-like processes over the thickenings at the entrance 

 of the nerves. 



The terminal neurons of both the vestibule and the 

 cochlea end in dendrites between the hair cells, and the 

 cell of each is upon its course to the medulla. 



The auditory nerve is essentially double, consisting of a 

 dorsal or cochlear, and a ventral or vestibular part. 



Cochlear Root (Fig. 72). This is the true nerve of hear- 

 ing. Its fibres (Cock. R.) begin in dendrites between the cells 

 of the organ of Corti, have a cell upon their course, and when 



