Applied anatomy and kinesiology, the mechanism of muscular movement . flexes trunk and lower limbs andgrasps the handles, then lifts it to erect posture; to walk forwardwhile lifting the weight the extensors of the limbs must each inturn bear the added weight of the barrow. If there is resistance tothe forward motion the pectorals, anterior deltoid and upperserratus must act; work is thrown on the abdominal muscles andthe extensors of the trunk a little relieved by the backward trac-tion on the shoulders. To balance the weight as nearly as possible INDUSTRIAL OCCUPATIONS 321 on the spinal colu
Applied anatomy and kinesiology, the mechanism of muscular movement . flexes trunk and lower limbs andgrasps the handles, then lifts it to erect posture; to walk forwardwhile lifting the weight the extensors of the limbs must each inturn bear the added weight of the barrow. If there is resistance tothe forward motion the pectorals, anterior deltoid and upperserratus must act; work is thrown on the abdominal muscles andthe extensors of the trunk a little relieved by the backward trac-tion on the shoulders. To balance the weight as nearly as possible INDUSTRIAL OCCUPATIONS 321 on the spinal column and thus relieve both the flexor and extensormuscles of the trunk the workman leans forward in going forwardor up hill and backward in going backward or down hill. The combination of arm depression with pushing is found inwashing, using the old-fashioned washboard. The clothes arerubbed up and down against the board by alternate flexion andextension of the elbows, assisted by the arm elevators and depres-sors and reinforced by flexion and extension of the Fig. 194.—Action of the whole body in using the lawn mower Vigorous depression of the arms calls for contraction of the abdom-inal muscles to reinforce the movement. The abdominal musclesbeing relatively weaker in women than in men, women are moreapt to flex and extend the trunk in work of this kind by alternatecontraction and relaxation of the extensors of the hips and spine,the body weight acting in place of the flexor group. The musclesfor arm depression act all of the time to press the clothing againstthe board. Ironing is another occupation that has depression of the arm asa leading feature. The heavy iron gives much of the needed pressure21 322 INDUSTRIAL OCCUPATIONS by its weight, so that one arm can do the work. The usual aid isgiven the arm muscles by action of the trunk muscles on the sidetoward the iron. Alternate flexion and extension of elbow aided by the usualpushing and pulling muscles move the iron
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