THE SKELETON 



57 



All these bones except the inferior maxilla are immovably 

 joined together in the adult by irregular, saw-tooth like articu- 

 lations. The inferior maxilla articulates with the temporal bones 

 in such a way as to permit not only rotation about the points of 

 articulation but also a certain amount of sliding from side to side 

 and from back to front, thus making possible the grinding move- 

 ments of chewing. 



Tsp 



E 



Md 



Fio. 28. A side view of the skull. O, occipital bone; T, temporal; Pr, parietal; 

 F, frontal ; S, sphenoid ;Z, malar; MX, maxilla; N, nasal ;E, ethmoid;!/, lachrymal; 

 Md, inferior maxilla. 



There are several features of the skull which call for special 

 comment. The foramen magnum (Fig. 29) is a large opening into 

 the cranial cavity through the occipital bone; through it the 

 spinal cord passes on its way to the brain. On each side of the 



