OF THE MOTOEY APPARATUS IN MAN. 137 



ethmoid and sphenoid contribute also to the formation of the 

 face. 



These bones assist in forming certain osseous cavities con- 

 nected with the face, as the orbits ( 241), the nasal fossae, 

 and the mouth. 



The skeleton of the nose is completed by cartilages, which 

 being removed in the skeleton, makes the anterior openings of 

 the nasal fossae appear so large. These cavities are very 

 large and complex, communicating with the anterior and 

 posterior ethmoid cells ; the sphenoidal and superior maxillary 

 and frontal sinuses, and also with the middle ear. They 

 are separated from each other by an osseous and cartilaginous 

 partition or septum, and from the mouth by the osseous 

 palate. It is in the cavities of the nostrils that we find the 

 so-called turbinated bones, of which two are distinct bones, 

 the other four being but processes of the ethmoidal. The 

 importance of these bones, as regards the sense of smell, has 

 been already adverted to. 



ttn mo c 



Fig. 90. -Head of the Horse.* 



It is into the superior maxillary bone (speaking with refe- 

 rence to man) that are implanted all the teeth of the upper 

 jaw.J In youth it is, like most other bones, formed of 



* oc, t, f, occipital, temporal, and frontal bones ; n, nasal bone ; m y 

 superior maxillary; im, intermaxillary; mi, inferior maxillary; o, orbit; 

 t, incisive teeth ; c, canine ; mo, molar. 



t Principal muscles of the face and head: o, orbicular muscles of the eye- 

 lids, intended to close the eyelids and protect the eyes; bb, orbicular muscle 

 of the lips, intended to close them and to contribute greatly to speech, the 

 expression of the passions, &c. ; j, muscles of the cheeks ; m, masseter 

 muscle, intended to close the jaws by raising the lower maxillary bone ; 

 t , temporal muscle having the same function : z, zygomatic arch ; c, articu- 

 lation of the lower jaw ; a, auditory meatus and mastoid process. 



J Anatomists now generally admit that mail has intermaxillary bones as 



