Transversus Thoracis - Podcast Version 0:00 / 0:00 1x 0.25x 0.5x 0.75x 1x 1.25x 1.5x 1.75x 2x The transversus thoracis is a muscle of the thoracic wall. It is located on the internal surface of the thoracic wall and is continuous with the transversus abdominis inferiorly. Attachments: Arises from the posterior surface of the inferior sternum and costal cartilage of the lower ribs. The fibres ascend and attach onto the internal surface of costal cartilages 2-6. Actions: Weak depressor of the ribs during expiration. Innervation: Intercostal nerves (T2-T6). Blood supply: Internal thoracic artery. By TeachMeSeries Ltd (2026) Fig 1View of the internal aspect of the thoracic wall. The internal intercostal and transverse thoracis muscles are visible. Pro Feature - 3D Model You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Frequent questions What is the transversus thoracis muscle? The transversus thoracis is a muscle found on the internal surface of the thoracic wall. It plays a role in the structure and function of the thoracic cavity. Where does the transversus thoracis attach? This muscle originates from the posterior surface of the inferior sternum and the costal cartilage of the lower ribs, with its fibres ascending to attach to the internal surface of costal cartilages 2-6. What is the primary action of the transversus thoracis? The main action of the transversus thoracis is to act as a weak depressor of the ribs during expiration. This helps facilitate the breathing process. Which nerves innervate the transversus thoracis? The transversus thoracis is innervated by the intercostal nerves, specifically from T2 to T6. This innervation is crucial for its function during respiration. What is the blood supply for the transversus thoracis muscle? The blood supply to the transversus thoracis comes from the internal thoracic artery. This vascular supply is essential for maintaining the muscle's health and function. Rate This Article