ANATOMY. 



jnotion of the limbs, or their motion with 

 force in opposite directions, can only be 

 produced by the instrumentality of oppo- 

 site or antagonist muscles, of flexors* and 

 extensors answering to each other. For 

 instance, the biceps and brachialis inter- 

 nus, placed in the front of the arm, by 

 their contraction, bend the elbow, and 

 with such degree of force as the case re- 

 quires, or the strength admits of. The 

 relaxation of these muscles after the effort 

 would merely let the fore-arm drop down: 

 for the backstroke, therefore, and that 

 the arm may not only bend at the elbow, 

 but also extend and straighten itself with 

 force, other muscles, as the triceps and 

 anconeus, placed on the hinder part of 

 the arm, fetch back the fore-arm into a 

 straight line with the humerus, with no 

 less force than that with which it was be nt 

 out of it. It is evident, therefore, that the 

 animal functions require that particular 

 disposition of the muscles which we call 

 antagonist muscles. 



It often happens that the action of mus- 

 cles is wanted where their situation would 

 be inconvenient. In which case, the body 

 of the muscle is placed in some commo- 

 dious position at a distance, and it com- 

 municates with the point of action by 

 slender tendons. If the muscles which 

 move the fingers had been placed in the 

 palm or back of the hand, they would 

 have swelled that part to an awkward 

 and clumsy thickness. The beauty, the 

 proportions of the part, would have been 

 destroyed. They are therefore disposed 

 in the arm, and even up to the elbow, and 

 act by long tendons strapped down at the 

 wrist, and passing under the ligament to 

 the fingers, and to the joints of the fin- 

 gers, which they are severally to move. 

 In the same manner the muscles, which 

 move the toes and many of the joints of 

 the foot, are gracefully disposed in the 

 calf of the leg, instead of forming an un- 

 wieldy tumefaction in the foot itself. 



The great mechanical variety in the 

 figure of the muscles may be thus stated. 

 It appears to be a fixed law, that the con- 

 traction of a muscle shall be towards its 

 centre. Therefore the subject for me- 

 chanism on each occasion is, so to modify 

 the figure, and adjust the position of the 

 muscle, as to produce the motion requir- 

 ed, agreeably with this law. This can 

 only be done by giving to different mus- 

 cles a diversity of configuration, suited to 

 their several offices, and to their situation 

 with respect to the work which they 

 have to perform. On which account \ve 

 $nd them under a multiplicity of forms 



and attitudes ; sometimes with dot ft. 

 sometimes with treble tendons, some 

 times with none ; sometimes one tendon 

 to several muscles, at other times one 

 muscle to several tendons. The shape of 

 the organ is susceptible of an incalcula- 

 ble variety, whilst the original property 

 of the muscle, the law and line of its 

 contraction, remains the same, and is 

 simple. Herein the muscular system may 

 be said to bear a perfect resemblance to 

 our works of art. An artist does not alter 

 the native quality of his materials, or 

 their laws of action. He takes these as 

 he finds them. His skill and ingenuity 

 are employed in turning them, such as 

 they are, to his account, by giving to the 

 parts of his machine a form and relation, 

 in which these unalterable properties 

 may operate to the production of the ef- 

 fects intended. 



The muscular system would afford us 

 numerous examples of what may be call- 

 ed mechanical structure : i. e. of such 

 contrivances, employed to attain certain 

 objects, as a human artist would adopt on 

 similar occasions. One of the muscles of 

 the eye-ball presents us with a very per- 

 fect pully; by means of which the globe 

 of the eye is moved in a direction exactly 

 contrary to the original application ot'tlu 

 force. This muscle, which is called the 

 trochlearis, arises from the very back 

 part of the orbit : it has a long and slen- 

 der tendon, running through a pulley in 

 the inner part of the front margin of the 

 orbit, and then going back to be fixed in 

 the hind portion of the eye-ball. Thus it 

 draws the globe obliquely upwards and 

 forwards, although the line of the contrac- 

 tion of the muscle is directly back- 

 ward. 



In the toes and fingers the long ten- 

 don, which bends the first joint, passes 

 through the short tendon, which bend* 

 the second joint. 



The foot is placed at a considerable- 

 angle with the leg. It is manifest, there- 

 fore, that flexible strings, passing along 

 the interior of the angle, if left to them- 

 selves, would, when stretched, start from 

 it. The obvious preventive is to tie them 

 down, and this is done in fact. Across 

 the instep, or rather just above it, the 

 anatomist finds a strong ligament, under 

 which the tendons pass to the foot. The 

 effect of the ligament, as a bandage, can 

 be made evident to the senses ; for if it 

 be cut, the tendons start up. The sim- 

 plicity, yet the clearness of this contri 

 vance, its exact resemblance to establish- 

 ed resources of art, place it among tfie- 



