MECHANISM OF POSTURES. 141 



statues and in drawings, in wall decorations, and 

 on pottery, so that the history of expression by 

 postures can be studied with considerable complete- 

 ness and precision. The posture of a limb depends 

 upon the relative position of the bones of the limb ; 

 and this depends in its immediate mechanism upon 

 the result and action of the opposing muscles which 

 move the limb, the relative tone of the antagonistic 

 flexors and extensors, the adductors and abductors, 

 the pronators and supinators, etc. The posture of 

 the limb is the result of the balance of the opposing 

 muscles. It may be said, then, that a posture is the 

 resultant action of the balance of the opposing 

 muscles which move a part of the body. Taking 

 this meaning of the term posture, we may speak of 

 postures of other parts of the body besides the 

 limbs. The eyes are members moved by opposing 

 muscles ; we may, then, speak of their relative posi- 

 tion to one another, and the position of each with 

 regard to the axis of the orbit, as the postures of 

 the eyes. In the face the different parts are called 

 features. The cheeks, the openings of the eyes, nose, 

 and mouth, are features of the face. 



The features of the face are moved by opposing 

 muscles, so that it is convenient to speak of the 

 postures of the face, or facial postures, as the result 

 of the action or tone of the facial muscles. We 

 may also speak of postures of the head and trunk. 



A change of posture is the effect of movement ; 

 the posture is the result- of the last movement; the 

 cause of the last movement is therefore the cause of 

 the posture. We may describe in anatomical terms 



