VARIETIES OF 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 fe'SftStal 

 triceps muscles. On the other hand, 



some muscles have no tendon at all at r 

 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 

 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 -p lQ 3 7.__A di- 

 vane of a feather ; or a tendon may run gast 

 down the middle of the muscle (C), 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 bipeiiniform. 



