HUMAN PHYSIOLOGY 



whole back-boned series. The characters specially 

 distinctive of man are to be found in the equal and 

 even balancing of his head on his spine (Fig. 1). 

 The head of other animals has, so to speak, to be tied 



on to the spine a feature 

 well seen in the case of the 

 horse, for example, where 

 a very strong band of fibres 

 constituting a ligament, 

 literally ties the head on 

 to the back bone. The 

 balancing of man's head 

 on his spine without effort 

 has special reference to 

 his upright position, as 

 also has the particular 

 conformation of his back 

 bone. In the human spine 

 we find a series of curves 

 such as are found in no 

 other animal, and these 

 curves are specially adap- 

 ted for the more perfect 

 support of the head and 

 body at large in the erect 

 position which man of all 

 animals can alone easily 

 and perfectly assume. 

 With regard to the curves 

 of the spine, it may be 

 noted that these appear in 

 the child after birth, and are not fully completed 

 until some time after the child has risen from the 

 quadrupedal position in which it at first crawls to 

 assume the erect and human posture. It is a 



Fig. 1. HUMAN SKELETON 



Showing adaptation to erect 

 posture. 



