VARIETIES OF 1 MUSCLES. 71 



The shoulder is so much more firm that it serves as a 

 fixed point, and so that end of the biceps is the origin of 

 the muscle, and the radial attachment its insertion. The 

 distinction is, however, only relative : if the radius were 

 held immovable the muscle would move the shoulder 

 towards the radius, instead of the 

 radius towards the shoulder ; as, for 

 example, in going up a rope "hand 

 over hand." 



Varieties of Muscles. Many muscles 

 have the simple typical form of a belly 

 tapering towards each end, as A, Fig. 

 30 ; others divide at one end, and are 

 called two-headed, or biceps muscles, 

 and there are even three-headed or 

 triceps muscles. On the other hand, 

 some muscles have no tendon at all at 

 one end, the belly running right up to the bone to which 

 it is fixed, and some have no tendon at either end. Some- 

 times a tendon runs along the side of a a 

 muscle, and the fibres of the latter are at- 

 tached to it obliquely (B, Fig. 30) ; such 

 a muscle is called penniform or feather- 

 like, from a fancied resemblance to the 

 vane of a feather ; or a tendon may run gas 

 down the middle of the muscle (G), which is then called 

 bipenniform. Sometimes a tendon is found in the mid- 

 dle of the belly as w^ll as at each end (Fig. 31) ; such a 



Is the origin of a muscle under all circumstances its most fixed 

 end? Give an example. 



What is the simple typical form of a muscle? What is a biceps 

 muscle? What a triceps? Have all muscles tendons at each end? At 

 either end? Describe a penniform muscle. A bipenniform. 



