i8 



Physiology. 



Origin 



SHORTENED 



ELONGATED 



Fig. 1 1 . Action of the Calf Muscle of the Frog, showing the Relations of the 

 Sciatic Nerve. 



Structure of Muscle. Chipped beef shows well the 

 structure of muscle. The white network is connective 



tissue. Its work is to hold 

 the parts of the muscle to- 

 of Muscle Fibers gether and to support the 

 muscle as a whole. In the 

 meshes of the white network 

 is the red muscle tissue. The 

 partitions which run all 

 through the muscle are con- 

 tinuous with the muscle 

 sheath, and both are con- 

 tinuous with the tendons at 

 the ends of the muscle. In 

 fresh muscle the sheath and 

 the partitions are transpar- 

 ent, and are not very easily 



noticed. When meat is cooked or sal.ted the connective 

 tissue becomes white and opaque. 



f Muscle Fibers 



Muscle Sheath \ 



CROSS SECTION 



Tendon 



Insertion 

 LONGITUDINAL SECTION 



Fie. 12. The Structure of Muscle. 



