454 GENERAL ANATOMY". 



minal viscera, and even sometimes to produce their expulsion, 

 especially that of the latter, through an opening in the walls. 

 Efforts occasionally even go so far as to produce rupture of 

 the muscles, tendons or bones, and to cause ruptures of the 

 blood-vessels, hemorrhages and effusions of blood. 



730. The muscles which pass over several joints may 

 move them all. Thus the flexors of the fingers, after having 

 bent the third and second phalanges on the first, bend the lat- 

 ter on the metacarpus, and the hand on the fore-arm. One of 

 the two even contributes to pronation. It is the same in the 

 foot, where the common extensor of the toes bends the foot 

 upon the leg, and where even the same disposition occurs. 

 These muscles, which pass over several joints, have also other 

 uses. They are auxiliaries or supplementary parts to shorter 

 muscles, extending only to the two bones united by an articu- 

 lation. Thus, the biceps, semi-tendinosus and semi-membra- 

 nosus of the thigh, which pass over two articulations bending 

 in opposite directions, may assist or become the substitute in 

 their functions, of the extensor muscles of the pelvis upon the 

 thigh, and of the flexors of the thigh upon the leg. The mus- 

 cles of this kind, which are so numerous in the limbs, espe- 

 cially the inferior ones, and which equally exist in the di- 

 rection of extension and in that of flexion, appear also to be 

 intended for the purpose of rendering the act of standing se- 

 cure, by applying the articular surfaces against each other, 

 and preventing motion in all directions. 



731. Muscular motion is simple when it is impressed by 

 a single muscle or by several muscles which act in the same 

 direction. It is compound, when it is produced by several 

 muscles which act in different directions. Simple motion 

 commonly takes place in the direction of the muscle itself or 

 of the muscles which produce it. Thus the flexors of the fingers 

 bring them in their proper direction. In other cases, the mus- 

 cle being reflected, the direction of the motion is determined 

 by that of the portion of the muscle which extends from the 

 place where it changes its direction to the mobile part. Thus 

 the motion induced by the obliquus occuli longus, by the cir- 

 cumflexus muscle of the palate, the lateral peronsei, c., has a 



