THE CEANIUM AND FACE. 53 



large, bat-shaped bone and articulates with all the cranial 

 and many of the facial bones, binding them all together. 

 It has a body, two large wings, and two lesser wings and, 

 appears on the outside of the skull between the frontal 

 and the temporal bones behind the zygomatic process. 

 In the adult the body of the sphenoid is hollowed out into 

 the sphenoid sinuses, in which pus sometimes forms. 



The Ethmoid Bone. In front of and below the sphe- 

 noid and extending forward to the frontal bone is the 

 ethmoid, the last of the cranial bones. It consists of a 

 horizontal cribriform or sieve-like plate, from either side 

 of which depend lateral masses of ethmoid cells. To 

 the inner side of these masses are attached the thin 

 curved turbinated bones, superior and middle, while be- 

 tween them is a vertical plate that forms the bony sep- 

 tum of the nose. Rising from the upper surface of the 

 cribriform plate is another vertical plate, the crista galli, 

 with the olfactory grooves on either side for the reception 

 of the olfactory bulbs, filaments of the olfactory nerve 

 passing down through the perforations of the cribriform 

 plate to the nose. For the brain, which fills almost the 

 entire cavity of the cranium, is supported by the sphenoid 

 and ethmoid bones internally, as it is protected externally 

 by the other cranial bones. 



Ossification of Sutures. If premature ossification of 

 all the sutures occurs, idiocy results, while in cephalocele 

 there is a gap in the ossifying of the bones so that the 

 membranes or brain protrude. In rickets the forehead 

 is high and square and the face bones poorly developed, 

 so that the head looks larger than it really is. In Paget's 

 disease the bones enlarge and soften. This affects the 

 head but not the face and often the first thing noticed is 

 that the hat is too small. Craniotabes is thinning of the 

 bone in places, the bone becoming like parchment and 

 being easily bent. It is generally caused by pressure of 

 the pillow or the nurse's arm. 



Bones of the Face. The facial bones serve to form the 

 various features of the face, which after all are merely 



