THE USB OF MUSCLES IN THE BODY 



125 



V 



I lie last lumbar vertebra, and the perpendicular drawn from it 



will reach the ground between the two feet, within the basis of 



support afforded by them. With the feet close together, how- 



ever, the posture is not very stable, and in 



standing we commonly make it more so by 



slightly separating them so as to increase the 



base. The more one foot is in front of the other 



the more swaying back and forward will be 



compatible with safety; and the greater the 



lateral distance separating them the greater 



will be the lateral sway which is possible with- 



out falling. Consequently we see that a man 



about to make great movements with the upper 



part of his Body, as in fencing or boxing, or a 



soldier preparing for the bayonet exercise, al- 



ways commences by thrusting one foot for- 



ward obliquely, so as to increase his basis of 



support in both directions. 



The ease with which we can stand is largely 

 dependent upon the way in which the head is 

 almost balanced on the top of the vertebral 

 column, so that but little muscular effort is 

 needed to keep it upright. In the same way 

 the trunk is almost balanced on the hip-joints, 

 but not quite, its center of gravity falling rather 

 behind them; so that just as some muscular 

 effort is needed to keep the head from falling 

 forwards, some is needed to keep the trunk 



1 



FlQ> 53._Di ag ram 



from toppling backwards at the hips. In a black lines) which 



. ., ., , j . , pass before and be- 



similar manner other muscles are called into hind the joints and 

 play at other joints: as between the vertebral 



column and the pelvis, and at the knees and rigid and the body 

 ankles; and thus a certain rigidity, due to 

 muscular effort, extends all along the erect Body: which, on 

 account of the flexibility of its joints, could not otherwise be 

 balanced on its feet, as a statue can. Beginning (Fig. 53) at 

 the ankle-joint, we find it kept stiff in standing by the com- 

 bined and balanced contraction of the muscles passing from 

 the heel to the thigh, and from the dorsum of the foot to the shin- 



