THE COURSE OF THE NERVE. 219 



Prof. Youatt's description of the course of the tri- 

 geminus is as follows : 



"The trigeminus has been described as springing 

 by a multitude of filaments from the crura cerebelli, 

 and forthwith running for safety into the cavernous 

 sinuses, and there suddenly enlarging into or passing 

 through a ganglion. The nerve, as its name implies, 

 divides into three parts, the division taking place in 

 the cavernous sinus, after the superior or sensitive 

 root has been joined by the inferior or motor root. 

 Each part, before it leaves the cranium, assumes a dis- 

 tinct investment of dura mater. The branches are 

 named, from the parts to which they are destined, the 

 Ophthalmic, the Superior Maxillary, and the Inferior 

 Maxillary. 



" The ophthalmic is the smallest of the three. It is 

 formed within the sinus, where it is in conjunction 

 with the superior maxillary, which it soon leaves, and, 

 passing through the foramen lacerum into the orbit, 

 subdivides and forms three distinct branches the 

 Supra-orbital (the frontal), the Lachrymal, and the 

 Lateral Nasal (the nasal). The supra-orbital climbs 

 behind the muscles of the eye, giving filaments to the 

 rectus superior and the superior oblique, and some 

 also to the fatty matter of the eye. The main branch, 

 escaping through the superciliary foramen, is soon lost 

 in ramifications on the elevator of the superior eyelid, 

 the integument of the forehead, and the periosteum. 

 The lachrymal, as its name implies, is chiefly concerned 

 with the lachrymal gland; a few ramifications, how- 

 ever, are sent to the conjunctiva and also to the ciliary 

 glands of the upper eyelid, while a distinct twig of it 

 passes out at the angle between the zygoma and the 



