BRANCHES OF THE TRIFACIAL. 399 



The Frontal nerve mounts above the levator palpebrse, and runs 

 forward, resting upon that muscle, to the supra-orbital foramen, 

 through which it escapes upon the forehead, and supplies the mus- 

 cles and integument of that region. 



It gives off 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 

 muscles and integument at the inner angle of the eye and root of the 

 nose. 



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

 ophthalmic, receives a filament from the fourth nerve in the caver- 

 nous sinus, and passes outwards along the upper border of the exter- 

 nal rectus muscle to the lachrymal gland, where it divides into two 

 branches. The superior branch passes over the gland and through 

 a foramen in the malar bone, and is distributed upon the temple and 

 cheek, communicating with the temporo-malar and facial nerves. 

 The inferior branch supplies the lower surface of the gland, and ter- 

 minates in the integument of the upper lid communicating with the 

 facial nerve. 



The Nasal nerve 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 imme- 

 diately 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 supply- 

 ing the mucous membrane, near the anterior openings of the nares; 

 and an external branch which passes between the fibre-cartilages, 

 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 

 branches 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 distri- 

 buted 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 lachrymal sac, caruncula lachrymalis, conjunctiva, and 

 inner angle of the orbit. 



The SUPERIOR MAXILLARY NERVE proceeds from the middle of the 

 Casserian ganglion ; it passes forwards through the foramen rotun- 

 dum, crosses the spheno-m axillary 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 leash of branches, which are distributed to the 



