. Applied anatomy and kinesiology. t any tendency to displacement by the muscularbody wall. The bodies of the vertebra^ are thinner on their lower THE UPRIGHT POSITION .229 edges, their shape aiding also to maintain the arch of the spine. Thequadrnped position is a stable and economical one, with no apparentdifficulties in the maintenance of normal posture. The crouching start used by the sprinter imitates fairly well thenormal position of quadrupeds (compare Fig. 158). Notice thatthe knees are flexed to about a right angle, the thighs slanting for-ward about 45 degrees. To shift from this pos
. Applied anatomy and kinesiology. t any tendency to displacement by the muscularbody wall. The bodies of the vertebra^ are thinner on their lower THE UPRIGHT POSITION .229 edges, their shape aiding also to maintain the arch of the spine. Thequadrnped position is a stable and economical one, with no apparentdifficulties in the maintenance of normal posture. The crouching start used by the sprinter imitates fairly well thenormal position of quadrupeds (compare Fig. 158). Notice thatthe knees are flexed to about a right angle, the thighs slanting for-ward about 45 degrees. To shift from this position to the erectone he mvist raise the trunk through 90 degrees and extend theknees, making a total angular movement of 135 degrees. Noticealso that as one rises from the horizontal to the upright positionhe begins by extending his hip-joints and finishes by extending hislumbar spine. The orang-outang and other apes make the entiremovement in the hips and retain the primitive arch of the spineas they stand up. Which way is best?. Fig. 138.—Skeleton of the horse. (Chauveau.) This raises the fundamental question, What is the ideal standingposition? The ideal posture must satisfy at least two require-ments: it must be economic of muscular expenditure and it mustput the vital organs in a favorable position for performing theirfunctions. A jointed framework like the vertebrate skeleton can support aweight in upright position with least muscular expenditure whenits segments are in a straight line. With regard to the body as awhole, therefore, Miss Bancrofts window pole test sets the beststandard, classing all postures as faulty that put the body segmentsin a zigzag instead of a straight line. To rise to erect position, as the orang-outang does, by an angularmovement of 135 degrees in the hip-joints, makes a marked zigzag 230 THE UPRIGHT POSITION in the framework, for it carries the ihosacral joints directly behindthe hip-joints. By a comparison of the two skeletons it is easy tos
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