On this page
-
Text (1)
-
Untitled Article
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.
-
-
Transcript
-
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.
Additionally, when viewing full transcripts, extracted text may not be in the same order as the original document.
Untitled Article
but serve to pull the head backwards , move the arms , assist in respiration by acting on the ribs , and to give us an erect posture by extending the spine .
The cavity of the abdomen is completed by a few broajl and thin muscles , which constitute as it were Walls for covering in and containing the viscera . These also assist
respiration by helping to expel the air from the lungs , and they contribute to the movement of the body . The ribs are raised , and the cavity of the chest enlarged , during inspiration , by eleven double rows of small muscles
on each side . They grow out from the lower edge of one rib , are inserted into the upper rim of the next . Of the muscles within the body , the principal one is called the diaphragm , which is a broad thin muscle , occupying partly a horizontal position , when the body is erect 3 but
inclining downwards towards the back , and dividing the trunk of the body into two great cavities , the thorax and abdomen . It is the principal agent in respiration . The other muscles within the body arise from the sides of the lower end of the back-bone , and from the inner surface of the
pelvis , and passing down to be inserted into the thigh-bone , a little below its head , they help to turn the toes outward , and also to bend the thigh : when the limb is fixed they assist in bending the body .
Muscles of the superior extremities : these are usually divided into those that are situated on the shoulder-blade —on the arm—the fore-arm , and on the hand . Those situated on the shoulder-blade are inserted into the bone of the arm to effect its movements . There are seven of these .
The fore-arm is moved by four muscles , which arise from the upper part of the arm bone , and , passing over the elbow joint , are inserted into the upfper ends of the two bones of the fore-arm .
The hand is moved at the wrist by six muscles , of these three arise from the upper part of the fore-arm , and descending along its whole length are continued over the wrist , and "Tare inserted into the hand close to this joint j they bend the hand , and are consequently called its flexors . Three others called extensors , because they
Untitled Article
extend the hand , and bring it backwards , arise from the lower end of the arm bone , and are inserted into the back of the hand just beyond the wrist : all these muscles , before they reach the wrist , become slender tendons .
Besides these there are four short muscles which extend obliquely across from one bone of the fore-arm to the other , and roll the radius upon the ulna , carrying the wrist round in circles , hence we are enabled to turn the palm of the hand either upwards or downwards .
The fingers are principally moved by two flexors and one extensor . The former arise from the upper part of the fore-arm near the bend , and running down towards the wrist , send off four round tendons to each , which passing over the palm of the hand , are inserted into the several
bones of the fingers : one set of tendons pass through slits in the other set , which assist in binding them down when the fingers are bent . The extensor muscle arises above the elbow , passes down the fore-arm , and is divided into four round tendons , which may be felt on the back of the hand , and which are inserted into
all the bones of the four fingers for extending them . The motions of the fingers and those of the thumb are performed by muscles situated chiefly in the hand . In speaking of the openings in one set of tendons to admit others to pass through them , Dr . Paley asks , " What contrivance can be more mechanical ,
a slit in one tendon to let another pass through it ? This structure is found in the tendons which move the toes and fingers . The long tendon , as it is called , in the foot , which bends the
first joint of the toe , passes through the short tendon which bends the second joint , which course allows to the sinew more liberty , and a more commodious action , than it would
otherwise have been capable of exerting . There is nothing , I believe , in a silk or cotton mill , in the belts , or straps , or ropes , by which motion is communicated from one part of the machine to another , that is more artificial , or more evidently so , than this perforation . " It may be farther observed , that there is always an exact relation be-
Untitled Article
706 Natural Theology . No . XL—Muscular Motion .
-
-
Citation
-
Monthly Repository (1806-1838) and Unitarian Chronicle (1832-1833), Nov. 2, 1815, page 706, in the Nineteenth-Century Serials Edition (2008; 2018) ncse.ac.uk/periodicals/mruc/issues/vm2-ncseproduct1766/page/42/
-