The outer part 12b of the base joint is fixed to {HEAD ~ one end} of {TAIL ~ a lower arm} 14 
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The outer part 12b of the base joint is fixed to { HEAD ~ one end } of { TAIL ~ a lower arm } 14
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH