Transversus Thoracis Muscle as, Anterior View

Description

Arising from the posterior surface of the sternum and xiphoid process, the transversus thoracis (sternocostalis) fans superolaterally to attach along the internal surfaces of the costal cartilages, most often ribs 2 to 6. From an anterior perspective with the anterior thoracic wall opened, its thin slips lie deep to the internal intercostal muscles and superficial to the parietal pleura, forming part of the innermost layer of the thoracic wall. Medially it hugs the parasternal region; laterally its digitations taper toward the costochondral junctions. Clinically, this is the muscle that complicates “straight-in” parasternal access. Its relationship to the internal thoracic (internal mammary) vessels, which descend just lateral to the sternum and give off anterior intercostal branches, matters during internal thoracic artery harvest for coronary artery bypass grafting and during placement of parasternal chest drains or ports. Small but consequential. It also provides a clean teaching example of how the thoracic wall layers change as you move from parasternal to lateral rib spaces, and why pleural injury risk increases when dissecting deep to the costal cartilages. Use this artwork in gross anatomy and thoracic surgery teaching files when you need a clear anterior wall reference for the sternum, ribs, and costal cartilages, paired with the transversus thoracis fiber direction and attachments. It also suits atlas plates and operative approach diagrams covering parasternal incisions, internal thoracic vessel anatomy, and anterior intercostal spaces. Anatomical accuracy verified by SciePro's Medical Advisory Board.