[Analysis of "rising up mechanism" in months-old infants--determination of contact area and center of gravity by pedoscope].
The author studied how the rising up mechanism changed with the development of motor function in healthy infants. 1. The rising up mechanism can be evaluated from the body support pattern characteristic to each stage of posture development in supine and prone positions, the body support (contact) area and shift in the center of gravity. 2. The support patterns in supine position were classified into 4 types; S-I ("squid type", 2-4 mo), S-II ("platform type", 4-6 mo), S-III ("bell type", 7-10 mo), S-IV ("separate type"), and their characteristics were described. 3. The contact area in supine position gradually decreased as the support pattern changed from S-I (area ratio, approx. 2/3) to S-III (area ratio, 2/5). 4. The center of gravity in supine position was located at 10th thoracic vertebra at 2-4 mo, then rose with age until it was stabilized at 7th thoracic vertebra at 10 mo. 5. The support patterns in prone position were classified into 7 types; P-I ("protector type", 2-3 mo), P-II ("joint square and round type", 3-4 mo), P-III ("elongated oval type", 4 mo-first half of 5 mo), P-IV ("spindle type", 4 mo-latter half of 5 mo), P-V ("ginseng type", 5-6 mo), P-VI ("tetrapod type", 7-10 mo), P-VII ("oval type", 9 mo onward), and their characteristics were described. 6. The contact area in prone position gradually increased as the support pattern changed from P-I (area ratio, 3/5) to P-V (area ratio, 9/slightly over 10), and gradually decreased as it changed thereafter to P-VII (area ratio, 7/slightly under 10). 7. The center of gravity in prone position swung over a wide range. It was located at 12th thoracic vertebra at 2-3 mo, then ascended as far as 9th thoracic vertebra at 4 mo-first half of 5 mo, and descended thereafter to be stabilized at 2nd lumbar vertebra (level of navel) at around 10 mo. 8. Particular attention was paid to the development of rising up mechanism in the upper extremities in observation of changes in the support pattern.(ABSTRACT TRUNCATED AT 250 WORDS)
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D000367:Age Factors; D001696:Biomechanical Phenomena; D001835:Body Weight; D002657:Child Development / Q000502:physiology*; D005260:Female; D006112:Gravitation; D006801:Humans; D007223:Infant; D008297:Male; D011187:Posture