Also that sector is immediately west of you and would complete in and out flows to and fro from,Houston and Dallas
These frequencies used to be on the North Little Rock (KORK) feed. The ZME transmitters for sector 21 (CWS-Hi) and sector 20 (LIT-UH) are in north little rock and the feed based in Memphis wouldn't receive it too well. And you're correct, those sectors handle all NOBLY departures from DWF and all arrival traffic on the LIT transition to the BYP arrival, as well as IAH arrivals routed over LIT who haven't been cut short, and any IAH departures routed over PXV.
I'm not sure where the KORK feed went but it disappeared a few weeks ago.