{HEAD ~ This collar rotation} can be accomplished by {TAIL ~ a surgical assistant} or the chief surgeon without having to individually adjust and check the tilt angles of the individual microscopes 
accomplished by
{ HEAD ~ This collar rotation } can be accomplished by { TAIL ~ a surgical assistant } or the chief surgeon without having to individually adjust and check the tilt angles of the individual microscopes
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH