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