238 



THE CEANIAL NERVES. 



UNION OF THE GANGLION WITH NERVES : ITS BOOTS. The posterior border of 

 the ganglion receives three nerves. One of these, the long or sensory root, a slender 

 filament from the nasal branch of the ophthalmic trunk, joins the upper part of this 

 border. Another branch, the short or motor root, much thicker and shorter than the 

 preceding, and sometimes divided into two parts, is derived from the branch of the 

 third nerve to the inferior oblique muscle, and is connected with the lower part of 

 the ganglion. The middle or sympathetic root is a very small nerve which emanates 

 from the cavernous plexus of the sympathetic, and reaches the ganglion close to the 

 long upper root : these two nerves are frequently conjoined before reaching the 

 ganglion. The ganglion is sometimes very small, probably from the nerve-cells 

 being distributed along the nerves which are connected with it. 



BRANCHES OF THE GANGLION. From the fore part of the ganglion arise six or 

 eight short ciliary nerves, which undergo division as they pass forwards, so that they 

 form from twelve to twenty fine filaments as they reach the eyeball. They are dis- 



Fig. 156. NERVES OF THE ORBIT FROM THE 

 OUTER, SIDE. (From Sappey, after Hirscli- 

 feldandLeveille.) f 



The external rectus muscle has been divided 

 and turned down : 1, optic nerve ; "2, trunk of 

 the third nerve ; 3, its upper division passing 

 into the levator palpebrre and superior rectus ; 

 4, its long lower branch to the inferior oblique 

 muscle ; 5, the sixth nerve joined by twigs from 

 the sympathetic ; 6, Gasserian ganglion ; 7, 

 ophthalmic nerve ; 8, its nasal branch ; 9, ciliary 

 ganglion ; 10, its short, 11, its long, and 12, its 

 sympathetic root ; 13, short ciliary nerves ; 

 14, supraorbital nerve. 



posed in two bundles, springing from the upper and lower angles of the ganglion, 

 and being placed, the one set above, the other below the optic nerve. The lower set 

 is the more numerous, and is accompanied by the long ciliary nerves (from the 

 nasal), with which one or more of these branches are joined. Having entered the 

 eyeball by apertures in the back part of the sclerotic coat, the nerves are lodged in 

 grooves on its inner surface, and are finally distributed to the ciliary muscle, the 

 iris and the cornea (see the anatomy of the eye). 



Varieties. Additional roots to the ciliary ganglion have been observed by many 

 anatomists, derived from the upper division of the third nerve, from the fourth nerve, from 

 the lachrymal nerve, from the spheno-palatine ganglion, or from the sixth nerve. 



Absence of the long root is recorded : in this case it is probable that the corresponding* 

 fibres pass directly from the nasal by the long ciliary nerves to the eyeball. 



The sympathetic root may be represented by several fine filaments proceeding from the 

 cavernous plexus : according to Reichart this is the normal arrangement, the majority of the 

 filaments accompanying the third nerve. 



II. SUPERIOR MAXILLARY NERVE. 



The superior maxillary nerve, or second division of the fifth (n. mazilfaris), is 

 intermediate in size between the ophthalmic and the inferior maxillary trunks. 



It commences at the middle of the Gasserian ganglion, and, passing horizontally 

 forwards, soon leaves the skull by the foramen rotundum of the sphenoid bone. The 

 nerve then crosses the spheno-maxillary fossa, and, taking the name of infraor~bital> 

 enters the infraorbital canal of the upper maxilla, by which it is conducted to the 

 face. After emerging from the infraorbital foramen, it terminates beneath the 

 elevator of the upper lip in branches, which spread out to the side of the nose, the 

 lower eyelid, and the upper lip. 



