OPHTHALMIC NERVE. 



397 



surface without having any connexion with it, and maybe followed onwards 

 to the inferior maxillary nerve. The Casserian ganglion divides into three 

 .branches, the ophthalmic, superior maxillary, and inferior maxillary. 



The OPHTHALMIC NERVE is a short trunk, being not more than three 

 quarters of an inch in length ; it arises from the upper angle of the Casse- 

 rian ganglion, beneath the dura mater, and passes forwards through the 

 outer wall of the cavernous sinus, lying externally to the other nerves ; it 

 divides into three branches. Previously to its division it receives several 

 filaments from the carotid plexus, and gives off a small recurrent nerve, 

 that passes backwards with the recurrent branch of the fourth nerve between 

 the two layers of the teritorium to the lining membrane of the lateral sinus. 



The Branches of the ophthalmic nerve are, the 



Frontal, 



Lachrymal, 



Nasal. 



180.* 



The Frontal nerve mounts above the levator palpebrse, and runs for- 

 ward, resting upon that muscle, to the supra-orbital foramen, through 

 which it escapes upon the forehead, with the supra-orbital artery. It sup- 

 plies the conjunctiva and upper eyelid, and the iniegument of the cranium 

 as far as the vertex. 



The frontal nerve gives off but one small branch, the supra-trochlear, 

 which passes inwards above the pulley of the superior oblique muscle, and 

 ascends along the middle line of the forehead, distributing filaments to the 

 integument, to the inner angle of the eye and root of the nose, and to the 

 conjunctiva. 



The Lachrymal nerve, the smallest of the three branches of the ophthal- 

 mic, receives a filament from the fourth nerve in the cavernous sinus, and 

 passes outwards along the upper border of the external rectus muscle, and 

 in company with the lachrymal artery, to the lachrymal gland, where it 

 divides into two branches. The superior 

 branch passes along the upper surface 

 of the gland and through a foramen in 

 the malar bone, and is distributed upon 

 the temple and cheek, communicating 

 with the subcutaneus malse and facial 

 nerves. The inferior branch supplies 

 the lower surface of the gland and con- 

 junctiva, and terminates in the integu- 

 ment of the upper lid communicating 

 with the facial nerve. 



The Nasal nerve (naso-ciliaris) passes 

 forwards between the two heads of the 

 external rectus muscle, crosses the optic 

 nerve in company with the ophthalmic 

 artery, and enters the anterior ethmoidal 

 foramen immediately above the internal 

 rectus. It then traverses the upper part 

 of the ethmoid bone to the cribriform 

 plate, and passes downwards through 

 the slit-like opening by the side of the 



* A view of the distribution of the trifacial or 5th pair. 1. Orbit. 2. Antrum of Hi^h 

 more. 3. Tongue. 4. Lower maxilla. 5. Root of 5th pair forming the ganglion of 

 Casser. i>. 1st branch, Ophthalmic. 7. 2d branch, Superior maxillary. 8. 3d branch. 



34 



