Fig. 3
From: Fascial plane blocks for cardiothoracic surgery: a narrative review
A The internal mammary artery can be identified between the internal intercostal and transversus thoracis muscles. This anatomical plane represents the target of the transversus thoracis plane block. PMM, pectoralis major muscle; EIM, external intercostal muscle; IIM, internal intercostal muscle; TTM, transversus thoracis muscle; IMA, internal mammary artery. B Ultrasound anatomy after left internal mammary artery harvesting. Patients can have tissue disruption in the transversus thoracis plane muscle after the internal mammary artery harvest, making transversus thoracis muscle identification more difficult, and the deep parasternal intercostal plane block almost impossible to perform. PMM, pectoralis major muscle; EIM, external intercostal muscle; IIM, internal intercostal muscle