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Note: This text has been automatically extracted via Optical Character Recognition (OCR) software. The text has not been manually corrected and should not be relied on to be an accurate representation of the item.
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Untitled Article
tween the joint and the muscles which move it . That is , whatever kind of motion the joint , hy its construction , is capable of performing , that motion the annexed muscles , by their position , are capable of producing . If there be , for instance , at the elbow , a hinge
joint , capable of motion only in the same plane , the leaders as they are called , that is , the muscular tendons , are placed in directions parallel to the bone , so as , by the contraction or relaxation of the muscles to which they belong , to produce that motion and no other .
The celerity and precision of muscular motion may be well observed in the execution of many species of instrumental music , in which the changes produced by the hand of the musician are exceedingly rapid , are exactly measured , even when most minute ,
and display , on the part of the muscles , an obedience of action , alike wonderful for its quickness and its correctness . The same may be noticed in the hand of a person while in the act of writing : we may consider the number of
muscles which are brought to bear on the pen , and how the joint and adjusted operation of several tendons is concerned in every stroke , yet that 500 such strokes may be drawn in a minute . Scarcely a single letter can be turned without several of these tendinous
contractions , yet how currently does the work proceed ; and when we look at it , how faithful have the muscles been to their duty , how true to the order which habit has inculcated . For while
the hand-writing is the same , an exactitude of order is preserved , whether a person write well or ill . These instances of music and writing shew not only the quickness and precision of muscular action , but its docility .
Of the muscles of the inferior extremitiesy those which move the thigh arise from the pelvis , or the lower part of the trunk , descend aver the hip joint and are inserted into the thigh-bone below its articulating head . The leg is moved by eleven muscles
which arise partly from the pelvis , and partly from the upper end of the thi gh-bone , and which passing over the knee-joint are inserted into the bones of the leg . The foot is moved by three extensors and four flexors . The extensors , at least two of them , arise from the lower end of the thighbone , near the bend of the knee , and
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soon after unite into the great fleshy bellies , which , swelling out , form the calf of the leg , but decreasing where the leg begins to grow small , they each give off a broad thin
tendon which uniting form the tendo Achillis , to be | inserted into the extremity of the heel . These , which are very powerful muscles , extend the foot by bringing it backwards , and are principally engaged hi running , walking , leaping , &c .
Of the four flexors , the two first arise from the upper part of the tibia , or principal bone of the leg , and continuing fleshy about half way down that limb , send off two round tendons , which pass under the inner ankle , and are inserted into the bones of the foot . The other two flexors
arise from the upper part of the fibula or smaller bone of the leg , and send off two round tendons , which passing under the ankle , are inserted into the bones of the foot . The toes have likewise their
extensors and flexors , but on these we need not enlarge . We have seen that the muscles or flesh cover and spread over the whole frame of bones , connecting and securing its different
divisions and parts ; and not only producing all its movements , but also giving to it fulness , shape and beauty . We have seen likewise that the
action of the muscles is frequently wanted where their situation would be inconvenient , in which case the body of the muscle is placed in some commodious position at a distance , and made to communicate with the point of action by slender strings or tendons . " If the muscle , " says Dr . Paley ,
" 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 , 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 fingers , which they severally move . In like 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 unweildly tumefaction in the foot itself . The observation may be repeated of the
Untitled Article
Natural Theology . No . XL—Muscular Motion . 707
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Citation
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Monthly Repository (1806-1838) and Unitarian Chronicle (1832-1833), Nov. 2, 1815, page 707, in the Nineteenth-Century Serials Edition (2008; 2018) ncse.ac.uk/periodicals/mruc/issues/vm2-ncseproduct1766/page/43/
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