454 Grace B. Watkinson 
c) Ramus com. post. cum IX, 
d) Ramus recurrens.laryngeus, 
e) Ramus laryngo-pharyngeus,. 
f) Ramus com. post. cum nervo sympathico, 
g) Rami cardiaci, 
h) Rami pulmonales, 
i) Rami gastrici. 
XI. Accessorius Willisii. 
XH. Hypoglossus. 
A. Rami museulares, 
a) Ramus ad m. geniohyoideum, 
b) Ramus ad m. hyo-maxillarem. 
B. Rami linguales, 
a) Ramus lingualis posterior, 
b) Ramus lingualis anterior. 
I. Nervus olfactorius, the largest of the-eranial nerves, arises 
from the olfactory lobe which lies in a cavity almost entirely walled 
in by the frontal bone, dorsal and medial to the bulbus oculi and 
dorsal to the interorbital septum. The 'nerve emerges from the 
anterior end of this cavity, and passes: dorsally over the origin of 
musc. obliquus superior. It runs directly: forward in the dorsal 
region of the nasal cavity, resting laterally,:against the surface of 
the cartilaginous septum narium. It consists of a bundle of separate 
nerves which run parallel, like a single large nerve, as far forward 
as the olfactory organ, where the fibres spread apart and supply 
the olfactory mucose membrane. 
II. Nervus opticus is the next in size to olfaetorius and 
arises from the floor of the mid-brain at its anterior border, ventral 
to the erura cerebri. After the formation of the optie chiasma, 
each lateral nerve emerges from the brain cavity through a speeial 
opening in the chondrocranium close to the postero-dorsal limit of 
the interorbital septum. Each nerve takes a lateral and anterior 
direetion and erossing dorsally to muse. bursalis and laterally to 
muse. retractor bulbi enters the medial surface of the bulbus oeuli 
a little above and behind the geometrical polar axis. 
III. Nervus oculomotorius arises as a single nerve, from 
the erura cerebri, close to the mid-ventral line. It runs antero- 
laterally for a short distance within the membranous skull wall, 
through which it emerges, by a special opening, situated posterior 
to the orbit, at a point dorsal to the origin of muse. bursalis. 
