1886.] "* i J- [Stowell. 



N. Vidianus is a ribbon like offset of the meso-caudal angle of the 

 spheno-palatine ganglion (Fig, Vidian) ; its course is caudad to the 

 vidian canal. (The cephalic foramen of this canal is ventrad of the fora- 

 men lacerum anterius ; the canal is 5-10 mm. in length. The caudal 

 foramen opens upon the dorsum of the basi-spbenoid bone.) It lies along 

 the canal, and at the caudal foramen the entocranial nerve lies ventrad of 

 the Gasserian ganglion, and sends filaments to the eustachian tube, to the 

 pharyngeal mucosa, and becomes N. petrosus superficialis major, which 

 relates it to the facial nerve through a foramen in the petrous portion of 

 the temporal bone. 



At the cephalic end, near the spheno-palatine ganglion, two filaments 

 are given to the ophthalmic nerve ; the nerve is related with the maxillary 

 through filaments which join the nerve-trunk just peripherad of the rete 

 carotideum. 



NERVUS OPHTHALMICUS. 



General Description: N. ophthalmicus (Fig. Oph.) is the mesal offset 

 of the Gasserian ganglion ; it is the smallest of the three nerve-trunks 

 which proceed from the ganglion. The entocranial relations are with the 

 trochlear nerve, which rests upon its dorsal surface (a tracer is required 

 to separate the sheaths of these nerves) ; sometimes — not invariably — 

 these nerves are related by anastomotic filaments with the oculo-moto- 

 rius (III) along its ventral surface, and with the carotid artery by the rete 

 carotideum which involves the nerve-trunk. The foramen of exit is the 

 foramen lacerum anterius. The ectocranial relations are described in the 

 distribution of the two rami, N. frontalis and N. oculo-nasalis. It is dis- 

 tributed to the integument of the forehead, dorsal lid, side and end of the 

 nose, to the pili tactiles, to the conjunctiva, the lacus lachrymalis, and 

 the membrane over the turbinated bones ; to the trochlear and the ciliary 

 muscles ; to the lachrymal gland,; to the dura mater. It communicates 

 with the sympathic nerve. Its function is largely sensory. 



Special Description: Tbe central 5 mm. of the ecto cranial trunk is 

 involved in a dense rete carotideum ; about 3 mm. peripherad of the fora- 

 men lacerum anterius tbe trunk divides into two rami, N. frontalis and N. 

 oculo-nasalis. 



N. frontalis is directed dorsi mesad, and bends around the caudal sur- 

 face of the globe of the eye, lying ectad of the muscles ; there are really 

 two fasciculi in a common sheath ; when upon the dorsi-meson of the 

 globe the course is abruptly cephalad parallel with the meson to the mus- 

 culus orbicularis palpebise ; before the nerve perforates the muscle, a con- 

 siderable trunk, N. supra trochlearis (Fig. S-tro.), separates, and, follow- 

 ing the supra-orbital ridge just entad of the fascia, it gives filaments to the 

 dorsal lid, to the nasal duct, the angle of the eye (caruncula), and termi- 

 nates upon the nasal integument ; an anastomotic filament relates this 

 ramus with the palpebral branch of the maxillary nerve. Peripherad of 

 the point where N. frontalis pierces the orbicular muscle, it is known as 



