CHAPTER XV 

 SPECIAL PHYSIOLOGY OF THE MUSCLES 



THE subjects of the special physiology of the muscles are : 



1. The functions of the skeletal muscles in general. 



2. Standing, walking, and running. 



3. The voice. 



1. FUNCTIONS OF THE SKELETAL MUSCLES IN 

 GENERAL 



A. The bones and their articulations. The bones are 

 rigid bodies which support the various soft parts of the 

 animal body. They are formed 

 so as to furnish the greatest 

 strength with the least bulk. To 

 accomplish this the long bones 

 are hollow, and in the short bones 

 the lamellae are especially closely 

 packed in the direction in which 

 the greatest pressure or pull is 

 exerted (see Fig. 12). 



The articulations may be di- 

 vided into: 



i. Synchondrosis, the articu- 

 lation of two bones by means of 

 cartilage. In synchondrosis, the FlG I2- _ Upp ^ PART OF THE 

 bones retain, when no external FEMUR, SHOWING THE ARRANGE- 



forces are active, a definite posi- MENT OF THE LAMELLA 



(After H. Meyer.) 

 tion towards each Other; When The lamella are especially closely 



external forces are applied, the P acked in the direction in which 



the weight of the body acts and 

 bones Can move Upon each Other j n which the muscles inserted upon 



in all directions, the cartilage the trochanter raa J or act - 

 being twisted. Such movement is, however, very limited. 



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