Transversus thoracis muscle

The transversus thoracis muscle (also known as the triangularis sterni) is a thin plane of muscular and tendinous fibers situated upon the inner surface of the front wall of the chest. It is part of the anterior thoracic wall and plays a role in the movement of the ribs during respiration.

Anatomy

The transversus thoracis muscle originates from the posterior surface of the lower part of the sternum, the xiphoid process, and the costal cartilages of the lower three or four true ribs. It inserts into the inner surface of the costal cartilages of the second to the sixth ribs.

Innervation

The muscle is innervated by the intercostal nerves, which are the anterior rami of the thoracic spinal nerves.

Blood Supply

The blood supply to the transversus thoracis muscle is primarily provided by the internal thoracic artery, which runs along the inner surface of the thoracic wall.

Function

The primary function of the transversus thoracis muscle is to depress the ribs, which aids in forced expiration. This action is antagonistic to the external intercostal muscles, which elevate the ribs during inspiration.

Clinical Significance

The transversus thoracis muscle can be involved in various clinical conditions, including thoracic outlet syndrome and costochondritis. It may also be encountered during surgical procedures involving the thoracic cavity.

See Also

• Intercostal muscles
• Respiratory system
• Thoracic cavity
• Sternum

References

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