Going out on a limb since as Matt J points out it's not clear what exactly everything is, but...
I think what you need is metadata.
If you don't want to change your basic data type, maybe create an intermediary structure lookup to translate names like TD11 into a list of rows
lookup.TD11 = [1,2,3]
lookup.TD12 = [4,5,6]
...
Then you can access the rows like
target = "TD11"
EMG_HRstruct(loopup.(target)).data
which I guess you will have to somehow cat() together if you don't want the data for each row to be spit out separately.
If you can alter your data structure, maybe consider tabular data with a column for the file group
row|filegrp|data
---+-------+----
1 | TD11 | ...
2 | TD11 | ...
3 | TD11 | ...
4 | TD12 | ...
5 | TD12 | ...
6 | TD12 | ...
7 | TD13 | ...