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