Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct : for the use of schools and colleges . d, the intermediate partor body being rounded be-hind, and flat before, withtwo projectinglateral edgesfor giving attachment tothe sheaths of the ten-dons. [§ 278. In reviewing thestructure of the upper ex-tremity, we have seen thatit consists of a series oflevers joined together, and diminishing progressively in , the arm is longerthan the fore-arm ; the lat-ter is longer than theand each joint hand;of the er than the one whic
Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct : for the use of schools and colleges . d, the intermediate partor body being rounded be-hind, and flat before, withtwo projectinglateral edgesfor giving attachment tothe sheaths of the ten-dons. [§ 278. In reviewing thestructure of the upper ex-tremity, we have seen thatit consists of a series oflevers joined together, and diminishing progressively in , the arm is longerthan the fore-arm ; the lat-ter is longer than theand each joint hand;of the er than the one which itsucceeds. By this admi-rable arrangement the nu-merous joints in the handpermit that useful instru-ment to vary its motions in athousand different ways, toadapt it to the various bo-dies itis designed to handle,grasp, and touch; whilst thelong levers formed by thearm and fore-arm allow the hand to be rapidly changed to a con-siderable distance in all directions. It is principally by themovements of the humerus upon the scapula, that the directionof the limb is given ; the flexion and extension of the fore-arm L2 Fig. 159. Front. fingers is short-. n in 148 ORGANS OF LOCOMOTION regulating the length ; whilst the multiplied movements of thethumb and fingers perform the special acts which the hand waadesigned so admirably to execute. The quadrumana, like man,have the thumb opposable to the other fingers. It is this, in fact,which forms the true character of the hand. But the bones ofthe thumb in man are more lengthened and powerful, in propor-tion to the other fingers, than in monkeys, whose hand doesnot equal his in perfection ; for monkeys can neither seizeminute objects with that precision, nor grasp and support largeones with that firmness which is so essential to the dextrousperformance of the multitudinous purposes for which the handof man was designed.—T. W.] 1. PLAN OF THE ORGANS OF LOCOMOTION. § 279. The organs of progression in vertebrated animalsnever exceed fou
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectzoology, bookyear1870
