BRANCHES OF THE FIFTH XEItVE. 799 



between the two beads of tbe External rectus, and between tbe two divisions of 

 the third nerve, and passes obliquely inward across the optic nerve, beneath the 

 Superior oblique and Superior rectus muscles, to the inner wall of the orbit, 

 where it enters the anterior ethmoidal foramen. It then enters the cavity of the 

 cranium, traverses a shallow groove on the cribriform plate of the ethmoid bone, 

 and passes down, through the slit by the side of the crista galli, into the nose, 

 where it gives off two branches, an internal and an external. The internal 

 branch supplies the mucous membrane near the fore part of the septum of the 

 nose. The external branch supplies a few filaments to the mucous membrane 

 covering the fore part of the outer wall of the nares as far as the inferior spongy 

 bone. The nerve then descends in a groove on the back of the nasal bone and 

 leaves the cavity of the nose, between the lower border of the nasal bone and the 

 upper lateral cartilage of the nose. and. passing down beneath the Compressor 

 nasi, supplies the integument of the ala and the tip of the nose, joining with the 

 facial nerve. 



The branches of the nasal nerve are the ganglionic, ciliary, and infratroch- 

 lear. 



The gangl.ionic is a slender branch, about half an inch in length, which usually 

 arises from the nasal, between the two heads of the External rectus. It passes 

 forward on the outer side of the optic nerve, and enters the superior and posterior 

 angle of the ciliary ganglion, forming its superior or long root. It is sometimes 

 joined by a filament from the cavernous plexus of the sympathetic or from the 

 superior division of the third nerve. 



The long ciliary nerves^ two or three in number, are given off from the nasal 

 as it crosses the optic nerve. They join the short ciliary nerves from the ciliary 

 ganglion, pierce the posterior part of the sclerotic, and, running forward between 

 it and the choroid, are distributed to the ciliary muscles, iris, and cornea. 



The mfratrocUear branch is given off just before the nasal nerve passes 

 through the anterior ethmoidal foramen. It runs forward along the upper border 

 of the Internal rectus. and is joined, beneath the pulley of the Superior oblique, 

 by a filament from the supratrochlear nerve. It then passes to the inner angle 

 of the eye. and supplies the integument of the eyelids and side of the nose, the 

 conjunctiva, lachrymal sac. and caruncula lachrymalis. 



Ophthalmic Ganglion (Figs. 481, 482). 



Connected with the three divisions of the fifth nerve are four small ganglia. 

 With the first division is connected the ophthalmic ganglion ; with the second 

 division, the tphcHO-palatine or MeckeVs ganglion : and with the third, the otic 

 and submajcillary ganglia. All the four receive sensory filaments from the fifth, 

 and motor and sympathetic filaments from various sources ; these filaments are 

 called the roots of the ganglia. 



The Ophthalmic, Lenticular, or Ciliary Ganglion is a small, quadrangular, 

 flattened ganglion, of a reddish-gray color, and about the size of a pin's head, 

 situated at the back part of the orbit between the optic nerve and the External 

 rectus muscle, lying generally on the outer side of the ophthalmic artery. It is 

 enclosed in a quantity of loose fat. which makes its dissection somewhat difficult. 



Its branches of communication, or roots, are three, all of which enter its 

 posterior border. One, the long or sensory root, is derived from the nasal branch 

 of the ophthalmic and joins its superior angle. The second, the short or motor 

 root, is a short, thick nerve, occasionally divided into two parts, which is derived 

 from the branch of the third nerve to the Inferior oblique muscle, and is connected 

 with the inferior angle of the ganglion. The third, the sympathetic root, is a 

 slender filament from the cavernous plexus of the sympathetic. This is frequently 

 blended with the long root, though it sometimes passes to the ganglion separately. 

 According to Tiedemann. this ganglion receives a filament of communication from 

 the spheno-palatine ganglion. 



