35 Oblique Mufcles. [Book IX.- 



mufcle. What is gained, however, in extenfivenefs 

 of motion by the obliquity of fibres* is loft in force j 

 but this is more than compenfated by the oblique 

 ftructure allowing fpace for a much greater number 

 of mufcular fibres. Oblique mufcles have therefore 

 in both refpefts the advantage over thofe which are 

 ftrait, and are accordingly much more numerous in 

 the animal machine. 



There is no part of the ftru&ure of the aijhnal body,- 

 which is more calculated to excite our admiration, 

 than the manner in which the tendons of mufcles are 

 inferted into the bones. If, for inftance, the mufcle called 

 the biceps, which lies at the infide of the os humen, 

 and which is defigned to bend the fore-arm, inftead of 

 terminating at the upper part of the radius, had been 

 inferted half way between the elbow and wrift, it is 

 evident, that when the mufcle had contracted itfelf Ib 

 as to bring the fore-arm to a right angle with the os 

 humeri, the tendon rnuft have ftarted feveral inches 

 from its place, and have given the limb a very un- 

 pleafant appearance, and muft alfo have been attended 

 with feferal real inconveniences. By the tendon, how- 

 ever, being inferred near the joint, the motion of the 

 limb is performed without fo great a rifing of the ten- 

 don as to prove troublefome. By this ftiudure more- 

 over, the motions of the limb are much quicker tha# 

 if the tendon had been inferted lower dov/n towards 

 the wrift. By the tendon being inferted nearer the 

 axis of motion, it is alib evident, that a much fmaller 

 contraction of the mufcle is fufficient to prod&ce an 

 effect, than muft have been neceflfary to produce the 

 fame had the infertion of the tendon been half way be- 

 tween the elbow and the wrift. That univerfal rule 

 in mechanics, however, that what is gained in velo- 

 city 



