THE PALATE BONES. 



47 



the articulating borders, presents for examination an ex- 

 ternal and an internal surface. The external surface is 

 smooth, and divided by a ridge into an anterior grooved 

 and a posterior flat portion. The ridge, known as the 

 lachrymal ridge, terminates inferiorly in a well-marked, 

 hook-like process, which projects forward and articulates 

 with the superior maxillary. In front of the lachrymal 

 ridge is the groove, which, when the bone is articulated 

 with the nasal process of the superior maxillary, forms 

 the lachrymal canal. Posterior to the lachrymal ridge 

 the bone is smooth and forms part of the inner wall of 

 the orbit. The internal surface is 

 roughened and at times cellular; it 

 articulates with the ethmoid and in- 

 ferior turbinated. This bone develops 

 from one centre, which appears in 

 the second month. 



THE PALATE BONES. 



The palate consist of two irregu- 

 lar bones, placed at the posterior 

 portion of the nose, the outer wall 

 and floor of which they assist in 

 forming. They enter into the formation of the roof of 

 the mouth and floor of the orbit, and form part of the 

 inner wall of the maxillary sinus (antrum of Highmore). 

 The palate bones also assist in forming three fossae, the 

 pterygoid, zygomatic, and spheno-maxillary; and one 

 fissure, the spheno-maxillary. Each presents for ex- 

 amination a vertical, and a horizontal portion arranged 

 in the form of the letter L, and projecting upward from 

 the superior border of the vertical limb are two proc- 

 esses, a large anterior, the orbital, and a small pos- 

 terior, the sphenoidal. The horizontal portion presents 



FIG. 20. LACHRYMAL 

 BONE. 



