34 PRACTICAL ANATOMY. 



the nose is attached to the anterior inferior border. The 

 posterior superior border articulates with the crest of the 

 sphenoid ; the posterior inferior, with the vomer. The 

 horizontal plate is perforated on each side of the crista 

 galli with rows of foramina, and is, therefore, called the 

 cribriform plate. It is placed between the two orbital 

 plates of the frontal, filling the ethmoidal notch, and 

 helps to form the anterior fossa of the skull. Its superior 

 surface is narrow and grooved for the olfactory tracts and 

 bulbs. The foramina, fifteen to eighteen in number, are 



FIG. 14. ETHMOID BONE. 

 (Right lateral mass removed.) 



arranged in three rows, and transmit the branches of the 

 olfactory nerve to the nose. At the side of the crista 

 galli is the nasal fissure for the passage of the nasal 

 branch of the ophthalmic nerve. Anteriorly the cribri- 

 form plate is notched and expanded into two wings, 

 which articulate with the frontal spine, and posteriorly is 

 a deeper notch for articulation with the rostrum of the 

 sphenoid. These articulations form " groove-and-tongue 

 joints" (schindylesis). The lateral masses are pendent 

 from the lateral edges of the cribriform plate. They con- 

 sist of two vertical masses of thin-walled cells, some of 



