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Figure 1: Ultrasound images of the introduction of a PECS II block. (a) Target areas of the PECS II block. (b) First injection of the PECS II block, showing spreading of local anesthetic in the interfascial plane between the pectoralis major and pectoralis minor muscles. (c) Second injection of the PECS II block, showing spreading of local anesthetic in the interfascial plane between the pectoralis minor and serratus anterior muscles. PM, pectoralis major muscle; Pm, pectoralis minor muscle; SA, serratus anterior muscle; LA, local anesthetic; R3, third rib; R4, fourth rib. The arrow indicates the 23-gauge Quincke needle.