62 SPECIAL ANATOMY. 



63. 4. Ossa lacrymalia s. unguis, 



Lacrymal bones, 2. 



Situation: at the anterior part of the nasal wall of the orbit, 

 between the nasal process and the orbital surface of the superior 

 maxillary before the os planum of the Ethmoid, beneath the 

 frontal bone. 



Shape : quadrangular, flat, small, like a finger-nail ; translucent, 

 thin. 



Conjunctions : with the Superior Maxillary, the Ethmoid, 

 Frontal and Inferior Turbinate bones. 



1. External, orbital surface, divided by the crista lacrymalis with the 

 hamulus lacrymalis, into an anterior grooved half, which forms a part of the 

 fossa lacrymalis with the groove on the proc. nasalis of the superior maxilla, 

 and a posterior half. 



2. Internal surface, presents a groove which forms a portion of the middle 

 nasal chamber; and covers behind the cdlulce eikinoidales anteriares. 



Structure. The most brittle of the bones ; consisting of com- 

 pact substance. 



Development. One osseous centre at the 4th month. At 

 birth most completely formed. 



64. 5. Ossa Turbinata s. Conchse inferiores, 



Inferior Turbinate bones, 2. 



Situation : at the lowest part, on the external wall of the nasal 

 cavity, beneath the Ethmoid bone. 



Figure: twisted, shell-like. More pointed behind than before. 



Conjunctions: with the Superior Maxillary, Palate, Ethmoid 

 and Lacrymal bones. 



1. Internal surface, convex, looks towards the septum of the nasal cavity, 

 and sometimes touches it. 



2. External surface, concave, looks towards the Superior Maxillary bone, 

 and forms a portion of the inferior nasal chamber. 



3. Borders: a. The superior, unites with the nasal process of the Sup. 

 Maxillary bone ; behind with the Palate bone. It presents from before to 

 behind. 



1. Proc. lacrymalis, united at the apex with the Lacrymal, at the sides with 

 the upper jaw bone; forms, with the proc. nasal, of the Sup. Maxillary bone, 

 the can. lacrymalis. 



2. Proc. Maxillaris s. auricularis, hooked, contracts the opening of the 

 Jlntrum Highmori, to the inferior border of which it is attached. Behind this 

 a small border, for the Palate bone. 



3. Proc. Ethmoidalis, unites with the Proc. imcinnatijks of the Ethmoid. 



b. The Inferior free border, in the centre thicker than at the extremities, is 

 more or less distant from the nasal septum. 



