486 SECOND PAIR OF NERVES. 



form plate to the Schneiderian membrane. These ramifications 

 of the olfactory nerve seem to receive a coat from the dura 

 mater, as they are much more firm after they have passed through 

 it. They appear to be arranged in two rows as they proceed 

 from the ethmoid bone one running near to the septum, and 

 supplying the upper part of the membrane covering it; and the 

 other to the opposite surfaqp of the ethmoid bone so as to be 

 distributed over the upper and middle turbinated bones. 



The Second Pair, or the Optic Nerves, 



Originate from the Thalami Nervorum Opticorum, and appear 

 on the external and lower surface of the brain, on each side of 

 the sella turcica. 



Each optic nerve has two roots one from the thalamus, and 

 one from the nates of the tubercula quadrigemina. 



Each of them seems like a chord of medullary matter en- 

 closed in a coat derived from the pia mater, and has not the 

 fasciculated appearance of the other nerves. The medullary 

 matter, however, appears to be divided by processes that pass 

 through it, which are derived from the coat of the nerve. 



They proceed obliquely forward and inward, on each side 

 of the sella turcica, in contact with the brownish cineritious 

 substance, (pons Tarini,) in which the infundibulum and the 



removed in the section, which has been made longitudinally, through the left 

 nostril just to the left side of the septum, leaving the right nostril entire. 1, 

 Frontal sinus. 2, Os nasi. 3, Crista galli of the ethmoid. 4, Sphenoidal 

 sinus. 5, Sella turcica. 6, Basilar process of the occipital bone joining the 

 body of the sphenoid. 7, Posterior opening of the right nostril. 8, Trumpet 

 shaped orifice by which the Eustachian tube of the right side opens into the 

 pharynx. 9, Velum pendulum palati or soft palate, cleft near its middle. 

 10, Line of section of the hard or bony palate. , Olfactory nerve, b, Its 

 three roots of origin, c, Its bulb, from which, the filaments are seen proceed- 

 ing through the cribriform plate of the ethmoid, to supply the septum narium. 

 d, Nasal branch of the ophthalmic nerve ; this branch after being reflected 

 back from the orbit passes into the nostril, through the anterior foramen in the 

 cribriform plate, and divides there into two branches, e, Naso-palatine nerve, 

 a branch of the fifth pair. It comes off from the spheno-palatine ganglion or 

 ganglion of Meckel, gives off twigs to the lining membrane of the septum in 

 its course, passes through the foramen incisivum, where it forms the naso-pala- 

 tine ganglion or ganglion of Cloquet, is joined with its fellow of the opposite 

 side, and distributes branches (g) to the mucous membrane of the mouth cover- 

 ing the hard palate, h, Posterior palatine nerves. i } i, Septum nasi. 



