The other end of lower arm 14 is connected to one part 16a of a central joint 16 whose other part 16b is connected to {HEAD ~ one end} of {TAIL ~ an upper arm} 18 
The other end of lower arm 14 is connected to one part 16a of a central joint 16 whose other part 16b is connected to { HEAD ~ one end } of { TAIL ~ an upper arm } 18
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH 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