360 GENERAL ANATOMY. 



single and median, the others lateral and in pairs. In the 

 former, the lateral halves are similar to each other; in the lat- 

 ter, each of the bones is similar to that of the opposite side of 

 the body. There are in this respect only very slight irregu- 

 larities. 



The single bones, which are all situated on the median line, 

 are the vertebra, as well those which are moveable, as those 

 of the sacrum and coccyx; the sternum, the occipital bone, 

 the sphenoid, the ethmoid, the frontal bone, the vomer, the 

 inferior maxillar bone, and the hyoid bone. 



All the rest are paired or double, and are situated on the 

 sides of the median line, at a greater or less distance from that 

 line. 



The bones are divided according to their form, and accord- 

 ing to the proportion which their three geometrical dimensions 

 bear to each other, into long, broad, short, and mixed. In the 

 first, one of the dimensions greatly preponderates over the 

 other two; in the broad bones, the length and breadth greatly 

 exceed the thickness; in the short bones, the three dimensions 

 are nearly equal; and the mixed bones participate, in different 

 parts of their extent, of the characters of the bones of two kinds. 



575. The long bones, ossa longa sen cylindrica, are situ- 

 ated in the limbs, where they constitute broken or jointed co- 

 lumns. The number of these bones, in each fraction of the 

 limbs, increases, and their length diminishes, as we recede 

 from the trunk. Each long bone is divided into a body or 

 middle part, and two extremities. The body or diaphysis, is 

 cylindrical in some of them, and in others has the form of a 

 triangular prism. It is generally a little bent and twisted. 

 The extremities are enlarged. 



The broad bones, ossa lata, sue plana, are situated in the 

 trunk, where they constitute walls of open cavities, and more 

 or less solid. These bones, which are flattened in two oppo- 

 site directions, are curved, and some of them twisted. They 

 are semi-circular, quadrilateral, or polygonal. Their edges 

 are generally a little thickened. 



The short or thick bones, ossa crassa, are situated in the 

 vertebral column, in the hand, and in the foot, where, by their 

 assemblage and multiplicity, they form solid and moveable 



