192 ANATOMY OF THE HEAD. 



simultaneousl}^ is the edge of the nostrils drawn in opposite 

 directions; and of course the opening is enlarged ; while the 

 lateralis and the accessories serve to dilate the anterior of 

 the nasal cavity. The blood to the nostrils is principally 

 supplied by branches derived from the facial and the lateral 

 nasal. The nerves being derived from the first, fifth, and 

 seventh pairs. 



MUSCLES OF THE NOSE. 



The DILATATOR NARi LATERALIS. Arises. From the external 

 surface of the upper part of the intermaxillary bone : and is 

 inserted into the cartilaginous continuation of the inferior 

 turbinated bone. 



Dilatator nari inferior. Arises. From the inferior 

 border of the intermaxillary bone. Inserted. Into the upper 

 surface of the nasal cornu. 



Contractor nari. Origin. From the inner side of the 

 intermaxillary bone. Insertion. Into the cartilaginous con- 

 tinuation of the inferior turbinated bone. 



Dilatator narium. A bundle of fibres, stretching from 

 cartilage to cartilage of the nose. 



the physiology of the nasal organs. 



Comparative anatomy shows that the sense of smell 

 is in most animals placed at the entrance of the respira- 

 tory organs ; by wdiich they are made subservient to both 

 purposes of breathing and smelling ; and by the same means 

 are rendered as w^ell voluntary as involuntary agents ; for 

 the action of respiration will carry all the effluvia from bodies, 

 whether sought for or not, against the sensitive pituitary 

 membrane. The herbivorous tribes smell vegetable mat- 

 ters, and have an abhorrence of all fleshy odours. In all 

 the vertebrated animals, the parts connected with the organ 

 of smell are, like the parts composing the other organs of 

 sense, double. The cognizance taken of the volatile portions 

 of bodies continually flying off from them, and impressed 

 on the sensitive surface of the internal nostrils, is trans- 

 mitted by the nervous expansion of the olfactory nerves to 

 the brain ; where it produces the sensation we understand 

 by the name of smell. 



