108 



THE HUMAN BODY 



whole adult Body lies in the articulation between the sacrum and 

 the 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- 

 wards 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 



FIG. 56. Diagram 



illustrating the mus- forwards, some is needed to keep the trunk 

 bi e a S ck (dr Hne n s) in wS from toppling backwards at the hips. In a 

 pass before and be- smi ii ar manner other muscles are called into 



hind the joints and bv 



their balanced activ- play at other joints: as between the vertebral 

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

 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. 56) at 

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

 bined and balanced contraction of the muscles passing from 



