Ultrasound image of the pocket of fluid formation after the injection of a methylene blue-lidocaine solution using the t-TTP approach, at the level of the fifth interchondral space. The pocket of fluid is delimited by the dotted line. CP, costal pleura; D, dorsal; IE, external intercostal muscle; II, internal intercostal muscle; IIm, internal intercostal membrane; L, lateral; M, medial; Nt, needle tip; Pk, pocket of fluid, PP, pectoralis profunda muscle; RA, rectus abdominis muscle; S, sternum; TT, transversus thoracis muscle; V, ventral.