Joints between the fourchette and {HEAD ~ the anterior and posterior portions} maintain an opening formed by {TAIL ~ the cuff} in an open position 
Joints between the fourchette and { HEAD ~ the anterior and posterior portions } maintain an opening formed by { TAIL ~ the cuff } in an open position
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH