OLFACTORY NERVES. 451 



orbital, the alveolar and the palatine, which extend to the 

 Schneiderian membrane; but they are not of much importance. 



The veins of the nose correspond with the arteries. Those 

 which accompany the ethmoidal arteries open into the ocular 

 vein of the orbit, which terminates in the cavernous sinuses of 

 the head. The other veins ultimately terminate in the external 

 jugulars. 



The nerves of the nose form an important part of the struc- 

 ture ; they are derived from several sources ; but the most 

 important branches are those of the olfactory. 



The olfactory nerves form oblong bulbs, which lie on each 

 side of the crista gilli, on the depressed portions of the cribri- 

 form plate of the ethmoid bone, within the dura mater. These 

 bulbs are of a soft consistence, and resemble the cortical part of 

 the brain mixed with streaks of medullary matter. They send 

 off numerous filaments, which pass through the foramina of 

 the ethmoid bone, and receive a coat from the dura mater as 

 they pass through it. 



These filaments are so arranged that they form two rows, 

 one running near to the septum, and the other to the surface of 

 the cellular part of the ethmoid bone, and the os turbinatum : 

 and in addition to these are some intermediate filaments. 



When the Schneiderian membrane is peeled from the bones to 

 which it is attached, these nervous filaments are seen passing 

 from the foramina of the ethmoid bone to the attached surfaces : 

 one row passing upon that which covered the septum, and the 

 other to that of the opposite side ; while the intermediate fila- 

 ments take an anterior direction, but unite to the membrane as 

 soon as they come in contact with it. 



All of these can be traced downwards on the aforesaid surfaces 

 of the membrane for a considerable distance, when they grad- 

 ually sink into the substance of the membrane, and most pro- 

 bably terminate on the internal villous surface ; but they have 

 not been traced to their ultimate termination. They ramify so 

 that the branches form very acute angles with each other. On 

 the septum the different branches are arranged so as to form 



