I am finishing my basement and I am currently trying to get all the framing done. I have a walk-out basement and only about 1/2 of my basement is underground (a bit more, but not much). The portion of the basement that is above ground is 2x4 exterior walls (wood starts a good amount above the ground level, poured concrete walls below the studded walls). The walls that have 2x4s are all insulated between the studs. In one corner of my basement, each wall has a 2x4 going at a 45-degree angle from up high right in the corner to just above where the wall meets the poured concrete wall base. They are only nailed at the point where the angled 2x4 touches the corner, and again at the base, no nails in between. I was assuming this was for support for the corner but I wasn't sure if it was a leftover from when they built my house, or if it was still needed. Any ideas? I can post pictures if necessary. I would appreciate any help! Thank you!