56 THE HUMAN BODY 



vertebra in Fig. 26, consists in the adult of a single bone; but 

 cross-ridges on its ventral surface indicate the limits of the five 

 separate vertebrae of which it is composed in childhood. It is some- 

 what triangular in form, its base being directed upwards and 

 articulating with the under surface of the body of the fifth lumbar 

 vertebra. On its sides are large surfaces to which the arch bearing 

 the lower limbs is attached (see Fig. 17). Its ventral surface is 

 concave and smooth and presents four pairs of anterior sacral 

 foramina, which communicate with the neural canal. Its dorsal 

 surface, convex and roughened, has four similar pairs of posterior 

 sacral foramina. 



The coccyx (Fig. 27) calls for no special description. The four 

 bones which grow together, or ankylose, to form it, represent only 

 the bodies of vertebrae, and even those incompletely. 



Details of the Skull. An account of the bones which make up 

 the skull can conveniently be given in tabular form. Examination 

 of the table will show that all the bones are either single or paired. 

 Single bones are all median, paired bones occupy corresponding 

 positions on each side of the mid-line. Figs. 28 and 29 will enable 

 the reader to gain a fairly good notion of the form and relations 

 of individual bones; for greater detail works on anatomy should 

 be consulted. 

 Cranium: 



1 Frontal, forehead (Fig. 28, F). 



2 Parietal, crown (Fig. 28, Pr). 



1 Occipital, base of skull (Fig. 28, 0). 



2 Temporal, ear region (Fig. 28, T) . 



1 Sphenoid, base of cranium and back of orbit (Fig. 28, ). 

 1 Ethmoid, between cavities of cranium and nose (Fig. 28, E) . 

 Face: 



1 Inferior maxilla, lower jaw (Fig. 28, Md). 



2 Maxillae, upper jaw, front of hard palate (Fig. 28, MX), 



2 Palatine, back of hard palate, front of posterior nares 

 (Fig. 29, PO. 

 2 Nasal, bridge of nose (Fig. 28, N). 



1 Vomer, partition between nostrils (Fig. 29, V). 



2 Inferior turbinate, inside nostrils (not shown in Fig.) . 

 2 Malar, cheeks (Fig. 28, Z). 



2 Lachrymal, inside wall of orbit (Fig. 28, L). 



