FIRST PAIR OF NERVES. 485 



names, which generally are expressive of the functions of the 

 different parts to which they are distributed. 



Those which go to the nose, are anterior to all the others,, and 

 are, therefore, denominated 



The First Pair, or the Olfactory Nerves. 



They arise by three delicate white fibres (or roots) from the 

 under and posterior part of the anterior lobes of the brain, being 

 derived from the Corpora Striata. They proceed forward to 

 the depression on the cribriform plate of the ethmoid bone, on 

 each side of the crista galli. They lie in this course between 

 the pia mater and arachnoid imbedded in the sulcus between two 

 convolutions . The upper surface occupies a small sulcus 

 formed by the convolutions of the lower surface of the brain, 

 and, therefore, has a longitudinal ridge on it. The lower surface is 

 flat. Their texture is like that of the medullary part of the brain. 



On each side of the crista galli each of them forms a pulpy 

 enlargement of a brownish color, which is called the bulb, and 

 has been considered as a ganglion. 



Fig. 206.* 



From this bulb many fine and delicate cords go off, which 

 proceed through the dura mater and the foramina of the cribri- 



* Olfactory nerve, with its bulb ; and the branches which it sends to the lin- 

 ing membrane of the inner wall of the nostril, or septum. The other division 

 of its branches, sent to the upper and middle tucbinated bones, have been 



