42 GENERAL ANALYSIS. 



elasticity of the spinal column, on which the contents are 

 hung, the mobility of the ribs, and the pressure of the 

 abdominal walls, are remarkable illustrations of the 

 double utility of the Trunk-walls. 



FOURTH MEMBER OF THE BODY. 



67. THE TRUE MEMBERS OF LOCOMOTION are the 

 Lower Extremities, composed of two levers, having their 

 lower ends enlarged to furnish a better support on the 

 ground. 



68. THE LOWER EXTREMITIES MUST BE FURNISHED 

 with three joints : (1st) the upper ones, by which the ex- 

 tremities are attached to the pelvis, must be rotary, to 

 allow the levers to move in every direction ; (2d) the 

 levers must be divided in the middle by means of a 

 hinge-joint backward, to allow the lever to be readily 

 raised over an obstacle, or progression to be made up or 

 down an incline, or upon steps ; (3d) near the lower ex- 

 tremity of the lever it must be divided by another joint 

 of considerable mobility, to allow the broader part to 

 rest securely on every kind of surface. 



69. THE LOWER EXTREMITIES ARE COMPOSED of 

 three parts, the upper and lower leg, and the foot ; and 

 are furnished with three main joints, the hip, the knee, 

 and the ankle. 



70. THE SIMPLE USE OF THE LOWER EXTREMITIES is 

 to cause motion, and each of their divisions is composed 

 of a Framework or Skeleton, Muscles, Nerves, Skin, and 

 Blood-tubes. 



f Skeleton. 

 I Muscles. 



LOWER EXTREMITIES { Nerves. 



Skin. 

 [ Blood-tubes. 



71. BY THE FLEXIONS OF THE LOWER EXTREMITIES, 



very much of the jar which in walking acts upon the 



67. What are 68 With what must-? 69. Of how many parts are -? 

 70. What is - ? Write table of 71. What is pained - ? 



