SYSTEMATIC ANALYSIS OF THE BODY. 



37 



of levers to assist in producing motions more easily, and 

 the fourth of the muscles that act on the levers. 



54. THE TRUNK-WALLS ARE DIVISIBLE into the Pel- 

 vic, the Columnar, the costal (from costa, rib), and the 



abdominal. 



Pelvic. 



Abdominal. 



55. THE PELVIC PORTION OF THE TRUNK- WALLS HAS 

 FOR ITS FRAMEWORK a very notable broad ring called the 

 Pelvis, composed of several pieces so bound together that 

 they are immovable upon eacli other and are as a unit. 



56. THE PELVIS is that part of the framework of 

 the Body that is fixed in relation to all the rest, and 

 about which all the rest move; beneath it the lower ex- 

 tremities walk, and above it the back is flexible ; it is 

 the dead-point in the motions of the body, and in its 

 want of motion is only comparable to the cranial part 

 of the head. 



FIG. 56. 



Fig, 56 represents the Pelvic Ring seen from above, the upper margin 

 of which is several inches above the lower. 



57. THE PELVIC RING or bowl is not placed horizon- 





54. How ? Write table. 55, What has ? 56. What is ? Describe 

 Fig. 56. 5T. How is placed? 



