ORGANS OF SENSE. 161 
magnified four diameters: 4a, 6, c, d, cochlea; e-g, vestibule ; h,7,k, pos- 
terior semicircular canal; J, m, k, superior do. ; », 0,p, horizontal do. Fig. 
19, bony labyrinth from below, or from the side of the meatus auditorius 
internus : a—c, base of the cochlea with the small foramina for the passage 
of vessels and nerves; d, foramina for the nerves of the membranous laby- 
rinth ; e, cribriform lamina for the ampulle ; f, foramen for the aqueduct 
of the vestibule; g,h,i, posterior semicircular canal; 7,,/, superior do. ; 
m,n, 0, horizontal do. ; p, opening for the nerve of the posterior semicircular 
canal; g, aqueduct of the cochlea. fig. 20, labyrinth magnified four 
diameters to show the distribution of arteries in its interior: a, first coil of 
the cochlea broken open; 0b, inner surface covered by the periosteum; c, 
bony portion of the lamina spiralis in the first coil; d, vestibule; e, canai 
for the malleus muscle ; f,g,, artery for the labyrinth ; 4, posterior semi- 
circular canal with its arteries ; J, superior do. ; m, horizontal do.; , com- 
mon opening of the superior and posterior semicircular canal. Fig. 21, 
general relations of the membranous labyrinth: a@, cochlea; 0b, vestibule ; 
c-f, semicircular canals; g, lamina spiralis; h, edge of the lamina; 7, sinus 
and sacculus of the vestibule; 4, /,/*, ampulle of the three semicircular 
canals; m, horizontal canal; , auditory nerve; o, cochlear nerve; p, q, 
branches to the ampulle ; 7, middle branch to the sinus of the vestibule. 
Fig. 22, labyrinth opened: a-e, lamina spiralis; f, bony, g, cartilaginous 
portion; h,2, membranous portion ; /, space between the sinus and sac- 
culus ; m, sinus with which the fine openings of the semicircular canals 
communicate; 2, posterior semicircular canal; 0, superior do.; p, hori- 
zontal do., all with their ampulle. ig. 23, labyrinth from beneath to 
show the common opening of the superior and inferior semicircular canals, 
and the course of the auditory nerve: a, cochlea; 6, vestibule ; c¢, d, e, pos- 
terior semicircular canal; f, common opening; g, horizontal canal; e, h, 
superior canal; 2, facial nerve; 4, auditory nerve; /, cochlear nerve; m, 
nerve for the superior and horizontal semicircular canal; n, nerve to the 
sinus; 0, small nerve for the ampulla of the posterior canal. Fig. 24, 
magnified representation of the nerves of the labyrinth in the vestibule and 
on the ampulla. Fig. 25, distribution of the cochlear nerve on the lamina 
spiralis of the cochlea. Fig. 6, connected view of the different portions of 
the ear; a, external ear; b,c, meatus auditorius; d, attachment of the 
membrana tympani; e, membrana tympani in its ring; f,g,/, malleus; 
i,k, incus; m, stapes; n, vestibule; p, superior; q, posterior; 7, horizontal 
semicircular canals. 
4. Anatomy or THE Eve, or Orean oF VISION. 
A. Appendages of the Eye not directly concerned in Vision. 
In addition to the eyeball proper, with its apparatus of lenses, fluids, and 
membranes, in which the formation of images occurs, there are various 
appendages all more or less concerned in protecting the eye, and in enabling 
it to perform its functions properly and conveniently. These consist of the 
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