CRANIAL NERVES. 437 



part of the pons, the latter slightly above the former. They 

 are connected with grey matter, within the medulla oblon- 

 gata, and the sensory root may be traced backward as far 

 as the origin of the hypoglossal nerve. A ganglion (Gas- 

 serian) exists on the larger root opposite the great foramen, 

 at the base of the cranium, and immediately in front of 

 this it breaks up into three branches the ophthalmic, supe- 

 rior maxillary, and inferior maxillary which are distributed 

 to the parts about the eye, the upper and the lower jaw. 

 The ophthalmic enters the orbit, and supplies the various 

 parts therein contained, sending branches to the ophthalmic 

 ganglion of the sympathetic, the conjunctiva, muscles of the 

 eye, lachrymal gland and duct, the mucous membrane of 

 the nose, and the skin upon the forehead. 



The superior maxillary division passes forward beneath 

 the orbit, and through a special canal in the superior 

 maxillary bone. It is distributed to the maxillary sinus, 

 the upper grinding teeth, and to the skin and muscles on 

 the side of the face, nose, and upper lip. 



The inferior maxillary contains a considerable portion of 

 the fibres of the large root, and the whole of the small one. 

 The fibres of the latter are motor, and this division accord- 

 ingly contains both sensory and motor fibres unlike the 

 other two, which are sensory only. This portion is distri- 

 buted to the muscles, teeth, skin, &c. of the lower jaw, and 

 presides over the movements of the muscles acting on the 

 latter, namely, the temporalis, masseter, two pterygoid, and 

 the mylo-hyoid. A branch to the anterior part of the tongue 

 presides over taste and common sensation in this part. 



The trifacial is the great nerve of common sensation to 

 the face, as shown by the entire absence of this property in 

 the skin, eye, and nostrils when it has been divided. The 

 ophthalmic and superior maxillary divisions are exclusively 



