The front wheel is {TAIL ~ a caster wheel} pivotally attached to an arm directly or indirectly connected to {HEAD ~ the wheelchair frame} 
The front wheel is { TAIL ~ a caster wheel } pivotally attached to an arm directly or indirectly connected to { HEAD ~ the wheelchair frame }
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD