NERVUS TRIGEMINUS. 455 



from it.* It then rises a little, and enters the orbit at the in- 

 ternal extremity of the sphenoidal fissure; and, going forwards, 

 next to the periosteum of the upper part of the orbit, it enters 

 into the superior oblique muscle of the eye, near its middle, 

 and is distributed upon it. This nerve augments in volume/ as 

 it advances towards its destination. 



SECT. V. OF THE NERVUS MOTOR EXTERNUS. 



The Nervus Motor Externus, or sixth pair, having got into 

 the cavernous sinus, is placed at the external side of the inter- 

 nal carotid artery, and adheres closely to it. It there sends off 

 one or more filaments, which follow the internal carotid artery 

 through its canal, and anastomose in their descent with a branch 

 of the pterygoid nerve: the junction of these two forms the up- 

 per end of tke great sympathetic nerve, and runs down to the 

 superior cervical ganglion of the sympathetic in two or more 

 filaments generally. The sixth nerve enters the orbit through 

 the sphenoid fissure, and is there closely connected with the 

 nervus motor oculi and the Nasal nerve. It penetrates into 

 the substance of the rectus externus muscle, and is entirely dis- 

 tributed upon it; with the exception that sometimes it sends a 

 filament to the ophthalmic ganglion. 



SECT. VI. 'OF THE NERVUS TRIGEMINUS. 



This nerve, having formed the ganglion of Gasser, (Plexus 

 Gangliformis,) on the side of the petrous bone, then divides, 

 as mentioned, into three large trunks, the foremost of which is 

 the Ophthalmic Nerve: the second fasciculus is the Superior 

 Maxillary; and the third the Inferior Maxillary Nerve. 



The Ophthalmic Nerve, or the first branch of the trigeminus, 

 is smaller than either of the other two branches, and comes 

 from the superior part of the plexus gangliformis. It passes 

 along the external border of the cavernous sinus, and penetrates 

 the orbit through the sphenoidal fissure, on the outer side of, 

 and near the motor oculi. 



* Soemmering, Icones Oculi Human!. 



