The Boxes of the Skull. 155 



16. THE VOMER. 



The vomer is the median, somewhat sickle-shaped, vertical 

 plate of bone separating the ventral portions of the nasal fossae. 

 It is visible from the palatal surface through the incisive foramina, 

 but its extent is best shown in the divided skull. It forms a 

 support for the ventral border of the nasal septum, and its pos- 

 terior portion bears a shelf-like projection, the ala vomeris, which 

 assists in the support of the ethmoturbinal. 



17. THE LACRIMAL BONE. 



The lacrimal bone (os lacrimale) is a small element lying in the 

 anterior wall of the orbit. It is loosely articulated: with the sur- 

 rounding bones, and in the dried skull is frequently missing unless 

 care has been taken to keep it in place. It consists of a basal 

 portion, somewhat rectangular on its orbital surface, and of two 

 processes, namely, the subcutaneous process and the hamulus 

 lacrimalis. The subcutaneous process is the prominent hook-like 

 projection extending laterad beyond, the orbital rim. The hamulus 

 lacrimalis is a small process, directed toward the rasal cavity. It 

 bears a groove which, in association with a corresponding groove 

 of the maxillary bone, forms the first portion of the nasolacrimal 

 canal. 



18. THE PALATINE BONE. 



The palatine bone (os palatinum) forms the posterior portion 

 of the palatine bridge and the major portion of the lateral wall of the 

 nasopharynx. It consists of two portions — horizontal, and 

 perpendicular. The horizontal portion (pars horizontalis) is 

 that lying in the plane of the palatal surface. It is articulated 

 in front with the palatine process of the maxilla, the suture between 

 the two bones enclosing the greater palatine foramen, the 

 ventral termination of the pterygopalatine canal. The perpen- 

 dicular portion (pars perpendicularis) is the vertical plate ex- 

 tending backward from the palatine bridge. Its medial surface is 

 divided by a low ridge into a dorsal portion, in particular relation 

 to the nasopharynx, and a ventral portion, in relation to the oral 



