Figure 2D and 2E: Normal MR imaging planes and appearance of BP. D-E, At the level of lateral margin of MSM (star), oblique sagittal fat-suppressedT2-weighted (D) and T1-weighted (E) image show the formation of three trunks (UT-upper trunk, MT-middle trunk and LT-lower trunk) (white arrows onright, and circles on left), superior to subclavian vessels (open arrow, SA) and at lateral margin of MSM (yellow line), where most of the portion of anteriorscalene muscle has already ended.