324 



MAMMALIAN ANATOMY 



ethmoidal process ; and a long narrower posterior sphenoidal pro- 

 cess. 



The maxillary process (Fig. 253) is in the form of a hook. Its 

 outer border is thin behind, but widens in front and gives off the 

 anterior border of the horizontal plate of the bone. It is rough, and 

 ends in a sharp angle where it joins the anterior border of the vertical 

 plate ; it articulates with the inner side of the tuberosity and of the 

 orbital plate of the maxillary. It faces outward and forward. The 



FIG. 252. 



With Maxillary. 



Wall oj Nasal Chamber 

 With Lachrymal. 



With Ethmoid. 

 With Vomer. 



Spheno-palatine Foramen'. \l!j 

 With Presphenold. 



With Opposite Palatine. 



With Frontal.- 1~$/^^ 



s<0' *."* I >=O4 



One-half Posterior Nasal Spine. 



Vertical Plate. 



With Ptcrygoid. 

 LEFT PALATINE BONE, UPPER ASPECT. 



posterior border of the process is rounded and deeply emarginate ; it 

 curves into the outer border of the bone. At the base of the process, 

 equidistant from the outer and posterior borders, is a round foramen 

 leading into the posterior palatine canals, which run inward and 

 forward to open at the front part of the lower surface of the palatine 

 plate. 



The ethmoidal process of the vertical plate rises from the base 

 of the maxillary process as a thin scale of bone sloping upward and 

 inward. Its anterior border is jagged, and joins the posterior border 

 of the lachrymal, or of the os planum of the ethmoid ; it faces 

 forward and upward. Its superior border is nearly straight, or 

 slightly arched, and articulates with the orbital plate of the frontal. 

 The posterior limit is indicated by a fissure extending from the 

 superior border downward and forward to the large foramen. The 

 small triangle behind the fissure and in front of a sharp vertical 



