The toothed arch block has one end disposed in {HEAD ~ contact} with {TAIL ~ the arched notch} 
with
The toothed arch block has one end disposed in { HEAD ~ contact } with { TAIL ~ the arched notch }
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL