64 



THE POPULAR EDUCATOR. 



occipital, and meet each other in the centre, thus forming the 

 middle of the top and sides of the skull. In front of these 

 again is placed one large flat bone, shaped something like a 

 cockleshell the frontal ; this completes the upper surface of 

 the skull, and forms the forehead and the greater part of 

 the bony cavities for the eyes (the orbits) ; inserted into a 

 gap in the frontal, between the orbits, is placed the eth- 

 moid (sieve-like), a very light spongy bone, which helps 

 to complete the orbits, and contains the hinder portion of 

 the passages of the nose. Placed one on each side of the 

 skull, below the parietal joining them above and the oc- 

 cipital behind, are two irregularly-shaped bones, the tem- 

 poral ; these complete the sides of the skull, and contain the 



externally, and forming strong bony arches to protect the 

 others. In the first division are comprised the vomer, the two 

 nasal bones, and the two inferior turbinated bones these enter 

 into the composition of the nose ; the two lachrymal and two 

 palate bones, which complete the walls of the orbit and the 

 hinder portion of the hard palate. 



The five larger bones are the two superior maxillary, upper 

 jaw-bones ; the two malar, cheek-bones ; and the single large 

 inferior maxillary, lower jaw-bone. The superior maxillary are 

 irregularly-shaped bones, placed one on each side of the face, 

 meeting in the centre ; they form the largest part of the 

 front of the face, the floor of the orbits, and the roof of the 

 mouth, and into them are inserted the upper row of teeth. 



I. THE HUMAN SKULL. II. THE THORAX OB 

 CHEST. III. THE ATLAS. IV. A VER- 

 TEBRA. 



Kefs, to Nos. in Figs. I. 1, the occipital ; 2, 

 the parietal ; 3, the temporal ; 4, the 

 sphenoid ; 5, the frontal ; 6, the malar ; 

 7, the lachrymal ; 8, the nasal; 9, supe- 

 rior maxilla ; 10, inferior maxilla. II. 

 1, the costal ; 2, the costal cartilages ; 

 3, tho clavicle ; 4, the scapula ; 5, the sternum ; 6, the spinal column. III. 1, tlie body ; 2, section of process of axis ; 3, position 

 of ligament; 4, articulating process ; 5, transverse process ; G, spiuous process ; 7, spinal canal. 



internal organs of hearing, and also Bend forward a strong 

 process to articulate with tho cheek-bones, and from their 

 under surface a thin process, which gives attachment to some 

 of the muscles of the tongue and throat. Lastly, at the base 

 of the skull, and hardly seen on its upper surface, is a bone 

 shaped like a bat with its wings extended, the sphenoid 

 (wedgelike) ; this articulates with all the other bones of the 

 skull, and, like the keystone of an arch, binds them firmly 

 together. The junctions of all the bones of the skull are 

 in every instance those which are most conducive to strength 

 and firmness : either the opposing surfaces aro notched like a 

 saw, the teeth accurately interlocking, or else the edge of one 

 bone is bevelled off so as to overlay smoothly and exactly the 

 edge of the adjacent bone. 



Tho fourteen bones of which the face is composed may be 

 divided into two classes: nine, which aro small, light, and 

 fragile, placed internally; and five, which aro larger, placed 



Just below, and to the outer side of the orbits, the superior 

 maxillary are joined by a pair of thick flat pieces of bone, 

 the malar or cheek-bones ; these form the outer angles of the 

 orbits, and send a pair of processes to join those of the 

 temporal, and form with them strong arches to protect the 

 sides of the face. The inferior maxillary is a strong bone, 

 shaped like a horse-shoe, with the extremities prolonged up- 

 wards : each end of this bone ends in two processes, one for 

 the attachment of a muscle; the other, a smooth globular- 

 shaped head, is received into a cup-shaped depression in the 

 temporal bone, just below the orifice of the ear. This is the 

 only instance amongst the articulations of the bones of the 

 head and face where any degree of movement is permitted ; in 

 all the others firmness and strength are the desiderata; but 

 here, by means of the cup and ball joint, the great and com- 

 plex movements necessary for the performance of mastication 

 aro perfectly provided for. 



