{HEAD ~ A lower arm} has one end connected to the base rotatable joint member and {TAIL ~ another end} connected to a central joint member 
has
{ HEAD ~ A lower arm } has one end connected to the base rotatable joint member and { TAIL ~ another end } connected to a central joint member
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH