24 ANATOMY AND PHYSIOLOGY 



Sphenoid bone (os sphenoidale] . Immediately behind the 

 ethmoid, to which it is joined. Its shape resembles a bat with 

 the wings spread (Figs. 12 and 14). It consists of a body, wings, 

 and two pterygoid processes. The body is joined to the ethmoid 

 in front, and to the occipital behind. It is hollow, and its two 

 cavities (called the sphenoid sinuses} communicate with the nose. 

 The wings, two pairs greater and lesser extend outward from 

 the body at about the level of the orbits. The optic foramen, 

 for the optic nerve, is in the lesser wing. 



The processes extend downward from the body, completing 

 the back part of the sides of the nose. 



Note. The lateral extremities of the greater wings may be seen at the 

 sides of the skull, between the frontal and temporal bones; the sphenoid is 

 thus wedged in behind the face, between it and the other cranial bones. (The 

 name sphenoid signifies wedge-like.) 



ARTICULATIONS OF THE CRANIUM 



The joints of the cranium are called sutures. Most of them 

 are formed by the interlocking of irregular edges of the bones held 

 firmly together by fibrous tissue between them. Sometimes the 

 edges resemble saw-teeth in form, and then the suture is dentated 

 or serrated. Sometimes the edges are smooth and overlap each 

 other, and sometimes one fits between two others; but they are 

 always immovable. (For illustration, see Fig. 12.) 



The sutures which are most important for the nurse to recog- 

 nize are those formed with three borders of the parietal bones. 

 The two sagittal (or superior) borders, uniting with each other, 

 form the sagittal suture; the frontal borders, uniting with the 

 frontal bone, form the coronal suture, while the occipital borders, 

 uniting with the occipital bone, form the lambdoid suture. 



BONES OF THE FACE, 14 



Nasal 2 Palate 2 



Lacrimal 2 Inferior turbinated. .. 2 



Zygomatic 2 Vomer i 



Superior maxillary. . . 2 Inferior maxillary, or 



united, form the maxilla. mandible i 



Nasal bones (os nasale, sing.). Right and left. (Fig. 12.) 

 They are flat in structure and form the bridge of the nose, being 



