SENSE ORGANS OF AMIURUS. 357 
more slender, extends transversely inwards into the medulla oblongata, 
and also backwards into the spinal cord. It includes the transverse 
and ascending roots of the trigeminus (JV. V., asc. et trans.). In addi- 
tion to these three other more superficial roots enter the ganglionic 
complex, and their points of origin can be seen without dissection. 
Fig. 15, Pl. I. One of these has been already referred to as the 
motor root of the seventh (V. VZJ.), the others, which take origin 
high up from beneath the crest of the twberculum acusticum, are 
what I have referred to as acustic roots of the trigeminus. 
It is desirable at this stage to examine the branches which leave 
the trigeminal complex, and then to study the mode in which the 
various roots contribute to the formation of these. 
Examining the ganglionic complex in situ from the medial aspect 
(Fig. 17, Pl. L.), the strong Ramus lateralis V. is seen ascending 
obliquely backwards to the foramen through which it escapes in the 
occipital region. From the dorsal edge, various other dorsal branches 
arise, some extremely slender (0), which may only reach the mem- 
branes, or penetrate into the skull, others, the Ramus oticus (R. ot.), 
and Ramus ophthalmicus superficialis (R. 0. s.), are of greater im- 
portance. The course of the former’ is outwards and upwards to its 
foramen in the sphenotic, ot the latter forwards to its foramen above 
that, through which the larger Ramus ophthalmicus profundus 
escapes. The latter nerve carries with it on its medial aspect the 
trochlearis, but entirely within its sheath, so that it (VV. ZV.) can 
only be recognized in sections of the complex by its broad fibres 
contrasting with the narrow fibres of the ophthalmicus, Cutting 
across the R. ophthalmicus profundus the slender ciliary nerve, &. 
ciliaris, is seen to issue behind and outside it by a distinct foramen. 
The rest of the trigeminal group emerges by three distinct apertures, 
which are frequently not entirely surrounded by bone, but merely 
separated by bony spicules. They are for the infero-medial strand, 
the supero-lateral strand and the facialis. The two latter frequently 
issue together, but there may be a separating spicule of bone. I 
have selected the expressions infero-medial and supero-lateral strands 
for the bulk of the trigeminus group, because it is only after emer- 
gence through the skull, that the rearrangement into &. mazillaris, 
mandibularis, &c., takes place. 
* For the selection of this name for the dorsal branch in question, v. Van Wijhe:— 
“Over het Visceraalskelet en de Zenuven van den Kop der Ganoideu.” Leiden, 1880, p. 25. 
