eae eee pw Eten 
Pt ee lH witch NADVvOR TRIFACTAL NERVE. 639 
crosses the optic nerve two long ciliary branches (nn. ciliaris longi) arise, and pass 
forwards alongside the optic nerve to the eyeball. (¢) On the inner side of the 
optic nerve the infra-trochlear nerve (n. infra-trochlearis) arises, a slender branch 
which courses forward beneath the pulley of the superior oblique muscle to the 
front of the orbit. It ends on the face by supplying the skin of the root of the 
nose and the eyelids, and communicates either in the orbit or on the face with 
the supra-trochlear nerve. On the face it also communicates with infra-orbital 
branches of the facial nerve. 
In the nose the internal nasal branch supplies the mucous membrane of the 
fore part of the nasal septum: the external nasal branch supplies the fore part of 
the outer wall of the nose. 
On the face the terminal filaments of the nerve are distributed to the skin of 
the lower half and tip of the nose. ‘The superficial terminal branch communicates 
with the infra-orbital branches of the facial nerve (Fig. 458). 
The ciliary or lenticular ganglion (ganglion ciliare) is associated with the 
nasal branch of the ophthalmic nerve and with the lower division of the third 
nerve. It is a small reddish ganglion, placed between tlie external rectus muscle 
Lachrymal gland Frontal nerve Supra-orbital nerve 
Lachrymal nerve 
a : Supra-trochlear nerve 
Nerves to superior rectus and 
levator palpebre superioris, 
from oculo-motor nerve, — 
superior division 
Trochlear nerve —, 
Levator palpebre superioris 
ZZ -—-——«  Rectus superior 
“| AQ call 
=a a Obliquus superior 
Rectus internus Uy ee aay Nasal nerve 
} Infra-trochlear nerve 
\— eae internus 
—— Saye erve to rectus internus from 
tie eu be motor 
| s 
it : =a yphthalinie artery 
c Le se nerve 
Abducent nerve 
Oculo-motor nerve (inferior 
division) 
Lenticular ganglion — 
Nerve to rectus inferior, from 
oculo-motor nerve 
Lae ciliary nerves 
ae iris inferior 
Obliquus inferior 
Nerve to obliquus inferior, _— 
from oculo-motor nerve 
Fic. 460.—Scuematic REPRESENTATION OF THE NERVES WHICH TRAVERSE THE CAVITY OF THE ORBIT. 
and the optic nerve, and in front of the ophthalmic artery. Its roots are three in 
number: (1) sensory or long (radix longa), derived from the nasal branch of the 
ophthalmic nerve; (2) motor or short (radix brevis), derived from the inferior 
division of the third nerve; and (3) sympathetic, a slender filament from the 
cavernous plexus on the internal carotid artery, which may exist as an independent 
root or may be incorporated with the long root from the nasal nerve. The branches 
from the ganglion are twelve to fifteen short ciliary nerves (nn. ciliares breves), 
which pass to the eyeball in two groups above and below the optic nerve. They 
supply the coats of the eyeball, including the iris and ciliary muscles. The cireular 
fibres of the iris and the ciliary muscle are innervated by the third nerve; tie 
radial fibres of the iris by the sympathetie. 
Superior Maxillary Division of the Fifth Nerve (n. maxillaris)—This large 
nerve courses forwards from its origin in the Gasserian ganglion through the middle 
fossa of the base of the skull, beneath the dura mater, and in relation to the lower 
part of the cavernous sinus (Fig. 455, p. 635). Passing through the foramen 
rotundum in the root of the pteryg coid: process, it traverses the spheno-maxillary 
fossa. It enters the orbit as the infra-orbital nerve, through the spheno- maxillary 
fissure, and occupying successively the infra- orbital groove and canal, it finally 
appears on the face through the infra-orbital foramen (Fi ig. 461). 
The branches and communications of this nerve occur (@) in the cavity of the 
cranium, (4) in the spheno-maxillary fossa, (¢) in the infra-orbital canal, and (d) 
on the face. 
7 
