24 
ME. W. K. PARKER ON THE STRUCTURE AND 
cavum tympani the meatus ( m.a.e .), at its proximal part, is cut through and is carti¬ 
laginous and partly bony; this is the “annulus;” below this is the epihyal ( e.hy .), 
and below this the chorda tympani. 
21 st Section (Plate 4, fig. 9).—In this section the inner wall of the capsule is broken 
up into three tracts, for here the related nerves (VII., VIII.) enter. 
On its inner face the capsule appears very solid, this is partly due to the obliquity 
of the section, here, as we are at the proximal part of the cochlea, where it opens into 
the general vestibule ( vb .). The outer face of the capsule is very broken up here, and 
there are several small tracts of cartilage to be accounted for. Below the narrowed 
end of the inner wall of the capsule the tympanic cavity ( c.ty .) is seen as a large oval 
space, enlarged a little upwards; below this the annulus is still seen, and outside that 
one of the imperfect rings of the meatus (m.a.e.) ; further outwards at the edge of the 
section the folds of the outer skin, at the passage of the ear, are shown. 
Two fenestrae are cut through in the infero-external wall of the capsule, these are 
the fenestra rotunda ( f.r .) below, and the fenestra ovalis ( fs.o.) above ; the latter is 
partly occluded by a cartilaginous plate, the stapes (st.), which, being perforated 
by the stapedial artery (st.a.), appears in two pieces, these are the base and neck 
of the stapes ; to the latter a short nucleus of cartilage is seen to be articulated, 
and a joint cavity exists between the two. Here we have the inturned, orbicular 
part of the long crus of the incus (l.c.i.) 
Under the lessened tegmen tympani ( t.ty .) we see a round tract of cartilage ; this 
is the short crus of the incus (s.c.i.). 
22ncl Section (Plate 4, fig. 10).—This is from a part close behind the last section, 
and the description just given may serve, on the whole, for this. The head of the 
malleus is hidden by the short crus of the incus, and the cartilage is deficient in some 
degree. The facial nerve (VII.) is seen passing into its canal beneath the tegmen. 
The cartilaginous matrix of the “ annulus ” is shown for half its extent, and part of 
what seems to be another annulus belonging to the meatus is seen, both are lettered 
as meatus-cartilages (m.a.e). 
The three main openings of the capsule are still seen, namely, the meatus internus 
for the 7th and 8th nerves (VII., VIII.), the fenestra ovalis (fs.o.) with part of the 
base and one of the crura of the stapes (st.) in it; and, below, the fenestra rotunda 
(f.r.). Only the top of the incus (s.c.i.) is seen on the outside of the capsule, and over 
the stapes the facial nerve (VII.) is passing out. The flattening basioccipital cartilage 
(b.o.) is coalescing with the capsule on this side. 
23 rd Section (Plate 4, fig. 11).—This is a very instructive section, showing 
the relation of the visceral cartilages to the auditory capsule. That capsule is laid 
open in the fore part of the internal meatus, and the facial nerve (VII.) is seen 
from behind as it enters the capsule, burrowing through it, and then reappearing 
over the incus (i.) under the tegmen tympani. Its chorda tympani, or mandibular 
branch (VII.'), is seen below the epihyal before it crosses over (outside) it to join the 
