Elbow, forearm

I gather that 'ablaut now holds few
secrets'. How do the various words
for elbow, forearm, e.g. English
'ell', Latin 'ulna', Greek
'o:lene:', 'o:le:r' and 'o:llon' all
relate? I've seen the
Proto-Germanic form cited as
*alina:; is this an alternative
notation for *alino:?
Richard.