366 PROCEEDINGS OF THE CANADIAN INSTITUTE. 
separated from it, and is always lateral to it in position. It immedi- 
ately enters the rectus eaternus on the posterior margin of that 
muscle. 
BRANCHES OF THE TRIGEMINUS GROUP. 
The ramus lateralis trigemini leaves the skull by the foramen in 
the supraoccipital, and courses backwards near the middle line be- 
tween the lateral musculature, and that of the interspinous bones. 
It is reinforced immediately after leaving the skull by the important 
dorsal branches of the first, second and third spinal nerves, and acts 
as a collector for slenderer branches from all the other rami dorsales. 
(Figs. 6, 14, 15, le Nis) 
The ramus oticus emerges from its foramen in the sphenotic and 
supplies the mucous canal running backwards and forwards from this 
point. Two short cutaneous branches penetrate vertically the adduc- 
tor mandibule near its dorsal line of origin for the skin overlying 
that, and a larger posterior branch runs through the fibres of the 
adductor nandibule to become superficial over the levator opercul. 
The mucous canal in the preoperculum is supplied in its upper part 
by a descending branch, which runs underneath the adductor mandi- 
bule, and on the surface of the dilatator operculi to become super- 
ficial at the posterior edge of the former muscle. The ramus oticus 
thus contains ordinary sensory fibres in addition to those destined for 
the mucous canals. 
The ramus ophthalmicus superficiais emerges from the skull 
through a canal which is considerably larger than, and lies dorsally 
from that through which the 2. opht. profundus emerges. It gains 
the orbit immediately under the osseous roof of which it lies, and 
escapes from it on to the upper surface of the skull through a foramen 
above that through which the profundus passes. In its course to the 
mucous canals in the neighbourhood of the nasal sacs it crosses super- 
ficially to the outside of the prefundus, but does not communicate 
with it. In the orbit it is separated from the profundus by the 
origin of the dilutator opercult. 
The ramus ophthalmicus profundus follows the course implied 
above through the orbit, gives off a slender branch to join the ramus 
ciliaris, another to the skin and fat in front of the eye and along the 
outer border of the nasal sac. Immediately after reaching the upper 
