THE MUSCLES. 63 



is called chronic rheumatism. They are scarcely subject to any 

 diseases, but occasionally they tear themselves, or rupture their 

 tendons, by too violent and sudden exertion. The tendon which 

 is most apt to suffer is that called the tendon of Achilles,* pass- 

 ing from the strong muscle of the calf down to the end of the 

 heel bone ; instant lameness is the consequence, which continues 

 till the tendon becomes re-united. This is procured by keeping 

 the foot in a bandage, or a boot made for the purpose, by which the 

 heel is drawn up, so as to have the torn surfaces as near to one 

 another as possible. 



When a bone is broken, it must be obvious that the muscle will 

 no longer produce the natural action which the bone served to direct, 

 but will draw the piece that is broken off into some place where it 

 ought not to be. When the thigh-bone is broken, for example, the 

 strong muscles which pass along it from the pelvis to the leg, pull 

 up the lower fragment, so that the limb becomes shortened. It is 

 also liable to be distorted by the loose piece being pushed to one 

 side or other. In treating fractures, we require, therefore, first to 

 reduce them, or bring the broken ends into their proper places, and 

 then we have to maintain them in apposition, by the application of 

 an apparatus which will keep them immovable, till union has been 

 obtained. 



NAMES, ORIGIN, INSERTION, AND USES OF MUSCLES. 



MUSCLES OF THE INTEGUMENTS OF THE CRANIUM. 



Occipito-frontalis arises from the upper ridge of the occipital 

 bone ; its aponeurosis covers the upper part of the head. Inserted 

 into the skin of the eyebrows and root of the nose. Use To pull 

 the skin of the head backwards, and to raise the eyebrows and skin 

 of the forehead. 



Corrugator supercilii arises above the root of the nose. In- 

 serted into the inner part of the occipito-frontalis. Use To wrinkle 

 the eyebrows. 



MUSCLES OF THE EYELIDS. 



Orbicularis palpebrarum arises from around the outer edge of 



* So called from the mythological fable, that -when Thetis dipped her son Achilles in 

 the river Styx, to render him invulnerable, she held him with her finger and thumb by 

 this tendon. Hence this part escaped the contact of the stream, and it was here that 

 he received his death wound. 



