Fig. 3

Schematic illustration of the injection sites for local anesthetic during ultrasound-guided interpectoral and interpectoral-pectoserratus plane blocks. In the interpectoral block, the local anesthetic is injected between the pectoralis major and pectoralis minor muscles. In the interpectoral-pectoserratus plane block, local anesthetic is first injected between the pectoralis major and minor muscles (step 1), and then between the pectoralis minor and serratus anterior muscles (step 2)