ANATOMY AND PHYSIOLOGY. 



turned towards the reader. From the back of the body, the arch, 

 A, of the vertebra springs, enclosing a space which is occupied by 

 the spinal marrow. Then to serve as levers, for the purpose of 

 bending and turning the spine, we have two transverse processes, 

 passing out one on each side, and the spinous process passing 

 backward, forming the chain of projections felt under the skin, 

 which give the name to the whole column. These four-and-twenty 

 pieces are joined together, so as to allow of a little motion, and but 

 little, at any one joint, that the spinal marrow which passes down 

 through the canal formed by the apposition of the different rings, 

 may not be injured by too sudden a twist, but that the curves which 

 it forms in the various motions of the body may be gradual. 



Even when at rest, the spine is not straight, but curved in three 

 different places. First, it curves forward where it rests on the 

 pelvis, that it may not be exposed to too rough a shock when we 

 begin to move, from being in a state of rest. Secondly, it curves 

 backward in the region of the back, to increase the capacity of the 

 chest, in which the heart and lungs are to be lodged. Thirdly, 

 it curves forward again in the neck in order to bring the weight of 

 the head which rests on it, over the point of support between the 

 feet. Three regions are distinguished in the spine, first the cervical, 

 or that of the neck, consisting of seven vertebrae ; second, the 

 dorsal, or that of the back, consisting of twelve ; and third, the 

 lumbar, or that of the loins, consisting of five. The vertebrae of 

 the loins are the most movable ; it is here that the turning and 

 bending of the trunk chiefly take place, and consequently it is to 

 this region that injuries are the most apt to occur. 



To the twelve vertebra of the back the ribs are attached, twelve 

 on each side, in order to form the chest. It has often been asked 

 whether it were true that men had a rib fewer than women, in 

 consequence of the rib having been taken from Adam's side of 

 which his wife was to be formed. Of this it may be said, that 



