53'3 THE CRANIAL NERVES. 



fj. Tlie hranrlt to the ophtJinlmic fjaiif/Iion (radix longa ganglii ciliaris). very 

 slender, and about half an inch long, arises generally between the heads of the 

 external rectus : it lies on the outer side of the optic nerve, and enters the upper 

 and back part of the ophthalmic ganglion, constituting its lo/i// root. 



This small branch is sometimes joined by a filament from the cavenious plexus 

 of the sympathetic, or from the upper branch of the third nerve. 



h. The loufj c'diani nerves, two or three in number, are situated on the inner 

 side of the optic nerve : they join one or more of the nerves from the ophthalmic 

 ganglion (short ciliary), and after perforating the sclerotic coat of the eye, are 

 continued between it and the choroid to the ciliary muscle, the cornea, and 

 the iris. 



c. The infratrorlilear hrancli runs forwards along the inner side of the orbit 

 below the superior oblique muscle, and parallel to the supratrochlear nerve, from 

 which it receives, near the pulley of that muscle, a filament of connection. The 

 brancli is then contin^ied below the pulley to the inner angle of the eye. and 

 ends in filaments which supply the orbicular muscle of the lids, the caiamcida, 

 and the lachrymal sac, as well as the integument of the eyelids and side of 

 the nose. 



In the cavity of the nose the nasal nerve ends by dividing into the following 

 branches. 



(J. The hrancli. to the nasal septinn extends to the lower part of the partition 

 between the nasal fossae, supplj-ing the pituitary membrane near the fore part of 

 the septum. 



e. The loijjerfichil hrancli (extemus seu lateralis) descends in a groove on the 

 inner surface of the nasal bone ; and after leaving the nasal cavity lietween tiiat 

 bone and the lateral cartilage of the nose, it is directed downwards to the tip of 

 the nose, beneath the compressor naris muscle. "WTiile within the nasal fossa, 

 this l^ranch gives two or three filaments to the fore part of its outer wall, which 

 extend as far as the lower spongy bone. The cutaneous part is joined by a fila- 

 ment of the facial nerve. 



Varieties. — The frontal may give off a long slender accessory infra-trochlear 

 (Turner, loc. cit.). Branches of the nasal have been described as entering the 

 levator palpebra; superioris. Luschka describes, also, a sphcno-ethino'ulal branch 

 of the nasal, which jiasses through the posterior ethmoidal foramen and ramifies 

 in the mucous membrane of the sphenoidal sinus, and of the posterior ethmoidal 

 cells. 



Summary. — The first division of the fifth nerve is altogether sensory 

 in function. It fnrni.shes branches to the ball of the eye and the 

 lachrymal gland ; to the mucous membrane of the nose and eyelids ; to 

 the integument of the nose, the upper eyelid, the forehead, and the 

 upper part of the hairy scalp ; and to the muscles above the middle of 

 the circumference of the orbit. Some of the cutaneous and muscular 

 filaments join brandies of the facial nerve, and the nerve itself commu- 

 nicates with the sympathetic. 



Ophthalmic Ganglion. 



There are four small ganglia connected with the divisions of the fifth 

 nerve : the ophtlialmic ganglion with the first, Meckel's ganglion with 

 the second, and the otic and submaxillary ganglia with the third. 

 These ganglia, besides receiving branches from the sensoiy ])art of the 

 fifth, are each connected with a motoi' nerve from the third, the fifth, 

 or the facial, and with twigs from the sympathetic ; and the nerves 

 thus joining the ganglia are named their roots. 



The 02)]dhalmic or lenticular ganglion (gang, semilunarc, vel ciliare) 

 serves as a centre for the supply of nerves — motor, sensory, and sympa- 

 thetic — to the eyeball. It is a small reddish body, comjiressed laterally 

 and somewhat four-sided. It is situated at the back of the orbit, 



