The hollow structure includes {HEAD ~ a body portion} that is disposed concentrically about the rotational axis and which is substantially encased in {TAIL ~ the body structure} 
is substantially encased in
The hollow structure includes { HEAD ~ a body portion } that is disposed concentrically about the rotational axis and which is substantially encased in { TAIL ~ the body structure }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL