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EDWARD L. RICE 
5. OTIC REGION 
1. General description 
The otic region of the skull consists primarily of the large and 
complicated auditory capsules at the sides, connected ventrally 
by the forward portion of the basal plate and dorsally, at least 
as regards space relations, by the tectum posterius. The ques- 
tion whether the tectum belongs morphologically to this region 
has been discussed. The whole thus forms a transverse ring of 
the skull, but a ring of very different dimensions in its different 
parts; the anteroposterior extent of the tectum posterius is very 
slight, while that of the otic portion of the basal plate is rela- 
tively enormous. Dorsally and ventrally the otic and occipital 
regions are confluent; laterally the auditory capsule is separated 
from the occipital arch by a narrow slit, the fissura metotica 
(fig. 6, fis.m-ot.). Amnteriorly the boundary of the otic region is 
formed, in its median ventral portion, by the transverse ridge 
of the crista sellaris, to the side by the free margin of the otic 
capsule. From the lateral extremity of the crista to the capsule 
the boundary is completed by the recurved anterolateral margin 
of the basal plate. The complexity of the line of junction of 
basal plate and otic capsule, together with the peculiar position 
of the facialis foramen, is best postponed to a later paragraph 
(p. 144). 
Only two pairs of cartilaginous bars connect the otic region 
with the anterior parts of the skull—the taeniae marginales 
(fig. 1, t.marg.), springing from the topmost points of the otic 
capsules, and the trabeculae baseos cranii (fig. 2, trab.), arising 
at the lateral extremities of the crista sellaris. In close prox- 
imity to the anterodorsal curve of the otic capsule, but without 
contact, is the upper end of the epipterygoid (fig. 3, epzpt.). All 
of these structures belong rather to the temporal region and will 
be discussed in that connection (pp. 169 and 172). 
In addition to this general outline of the otic region, certain 
points demand detailed discussion. These are especially the 
external form of the auditory capsules, the cavity of the capsule, 
