SUPERIOR MAXILLARY NERVE. 441 



heads of the external rectus muscle, crosses the optic nerve in com- 

 pany 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 crista galli 

 into the nose, where it divides into two branches an internal branch 

 supplying the mucous membrane, near the anterior openings of the 

 nares ; and an external branch which passes between the fibro-carti- 

 lages, and is distributed to the integument at the extremity of the 

 nose. 



The Branches of the nasal nerve within the orbit are, the gangli- 

 onic, ciliary, and infra-trochlear ; in the nose it gives off one or two 

 filaments to the anterior ethmoidal cells and frontal sinus. The 

 ganglionic branch passes obliquely forwards to the superior angle of 

 the ciliary ganglion, forming its superior or long root. The ciliary 

 brandies are two or three filaments which are given off by the nasal as 

 it crosses the optic nerve. They pierce the posterior part of the 

 sclerotic, and pass between that tunic and the choroid to be distributed 

 to the iris. The infra-trochlear is given off just as the nerve is about 

 to enter the anterior ethmoidal foramen. It passes along the superior 

 border of the internal rectus to the inner angle of the eye, where it 

 communicates with the supra-trochlear nerve, and supplies the lachry- 

 mal sac, caruncula lachrymalis, conjunctiva, and inner angle of the 

 orbit. 



The SUPERIOR MAXILLARY NERVE, larger than the preceding, pro- 

 ceeds from the middle of the Casserian ganglion ; it passes forwards 

 through the foramen rotundum, crosses the spheno-maxillary fossa, and 

 enters the canal in the floor of the orbit, along which it runs to the 

 infra-orbital foramen. Emerging on the face, beneath the levator labii 

 superioris muscle, it divides into a number of branches, which are dis- 

 tributed to the lower eyelid and conjunctiva, and to the muscles and 

 integument of the upper lip, nose, and cheek, forming a plexus with 

 the facial nerve. 



The Branches of the superior maxillary nerve are divisible into 

 three groups: 1. Those which are given off in the spheno-maxillary 

 fossa. 2. Those in the infra-orbital canal ; and 3. Those on the face. 

 They may be thus arranged: 



("Orbital, 



Splteno- maxillary fossa, < Two from Meckel's ganglion, 

 (_ Posterior dental. 



T /. , ., , 7 \ Middle dental, 



Infra-orbital canal, j Anterior ^^ 



n 41 s J Muscular, 



On the face, { Cutaneous. 



The Orbital branch (n. subcutaneus make) enters the orbit through 



