THE SKULL THE CKANITJM 



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Articulations. The ethmoid articulates with the presphenoid, 

 the orbitosphenoid, the frontal, the palatine, the maxillary, the nasal, 

 and the vomer ; it sometimes joins the lachrymal and the maxillo- 

 turbinal. 



VARIATIONS IN THE ETHMOID BONE. 

 VARIATIONS IN SIZE. 



The following measurements were taken of twenty-five ethmoid 

 bones : 



The maximum vertical height at right angles to the lower margin 

 of the lateral surface. 



The maximum length measured parallel to the lower margin. 



The maximum transverse width. 



HUMAN ETHMOID BONE. 



The human ethmoid comprises the same parts as the ethmoid of 

 the cat, namely, the cribriform plate, the perpendicular plate, or 

 mesethmoid, and the two lateral ethnioids, or ethmo-turbinals, but 

 the increase in the size of the brain and the consequent increase in 

 the size of the anterior end of the cranial cavity have led to changes 

 which modify materially many important details. The cribriform 

 plate is relatively narrower, and its intracranial surface is elevated at 

 the anterior end into a strong median crest, the crista galli, 1 with ex- 

 panded basal alar processes. To its nasal surface in the middle line 

 is fastened the edge of the mesethmoid. It will be noticed that the 



A cock's comb. 



