74 



THE HUMAN BODY. 



presents in the middle line a series of four bones, the basi- 

 occipital, basi-sphenoid, presphenoid, and basi-ethmoid, which 

 answer pretty much to the bodies of four vertebra?, and have 

 attached to them the thin bones which inclose the skull-cavity 

 (which may be likened to an enlarged neural canal) on the 

 sides and top. In the Human Body, however, these bones 



o 



FIG. 29. A side/viexv of the skull. O, occipital bone : T, temporal ; Pr, parie- 

 tal ; F, frontal; &', sphenoid ; Z, malar ; MX, maxilla; N, nasal; E, ethmoid; ,, 

 lachrymal; Md, inferior maxilla. 



very soon ankylose with others or with one another; although 

 they remain distinct throughout life in the skulls of very 

 many lower animals. On the base of the skull, besides many 

 small apertures by which nerves and blood-vessels pass in or 

 out, is a large aperture, the foramen magnum, through which 

 the spinal cord passes in to join the brain. 



