Transversus Thoracis Muscle

The Transversus Thoracis consists of four to five superolateral slips that lie on the posterior surface of the sternum, costal cartilages, and xiphoid process. They extend from the xiphoid process and the sternum to the second through the sixth costal cartilages.

The internal thoracic artery descends directly behind the costal cartilages, the internal intercostal muscles, and the external intercostal membranes. The pleura and transversus thoracis muscle lie posterior to the internal thoracic artery.