56 A MANUAL OF ANATOMY. 



cavity through the sphenoidal fissure in three divisions, the 

 frontal, lachrymal, and the nasal. 



The frontal and lachrymal nerves enter above the rectus 

 externus, the nasal between the two heads of that muscle. 



The frontal and lachrymal branches have already been 

 given above. (Pages 49 and 50.) 



The Nasal Nerve. Fig. 13. Diag. 4. 



This nerve runs forward and inward between the rectus 

 superior and the optic nerve to the inner wall of the orbit, 

 where it enters the anterior ethmoidal foramen, passes 

 through it into the cranial cavity, runs forward on the outer 

 border of the cribriform plate of the ethmoid bone, leaves 

 the cranium by traversing the nasal slit at the side of the 

 crista galli, and appears in the nasal fossa, where it termi- 

 nates in three branches. 



In the orbit the nerve gives off the following branches : 



Between the two heads of the rectus externus, the long- 

 root to the ophthalmic ganglion. A very slender filament 

 about half an inch long. 



Two long- ciliary filaments to the eye. These run along 

 the inner side of the optic nerve. 



The infratrochlear nerve is the last branch given off 

 just before the nerve leaves the orbit It passes forward 

 beneath the pulley for the superior oblique and supplies the 

 integument about the inner part of the eye and upper part 

 of the nose, also the mucous membrane of the inner part of 

 the eye, lachrymal sac, and caruncle. 



The remaining branches will be given when describing 

 the nasal fossae. 



The Ophthalmic, or Lenticular Ganglion. Fig. 1 1 . 



This is a ganglion developed in connection with the oph- 

 thalmic division of the fifth nerve. It is about as large as 



