transversus thoracis

The tranversus thoracis lies internal to the thoracic cage, anteriorly. It is a thin plane of muscular and tendinous fibers, situated upon the inner surface of the front wall of the chest. It is in the same layer as the subcostal muscles. It arises on either side from the lower third of the posterior surface of the body of the sternum, from the posterior surface of the xiphoid process, and from the sternal ends of the costal cartilages of the lower three or four true ribs. Its fibers diverge upward and lateralward, to be inserted by slips into the lower borders and inner surfaces of the costal cartilages of the second, third, fourth, fifth, and sixth ribs. The lowest fibers of this muscle are horizontal in their direction, and are continuous with those of the Transversus abdominis; the intermediate fibers are oblique, while the highest are almost vertical. This muscle varies in its attachments, not only in different subjects, but on opposite sides of the same subject. [WP,unvetted]. Every claim on this page comes from the Leumas anatomy graph and carries its source.

What the transversus thoracis is

The tranversus thoracis lies internal to the thoracic cage, anteriorly. It is a thin plane of muscular and tendinous fibers, situated upon the inner surface of the front wall of the chest. It is in the same layer as the subcostal muscles. It arises on either side from the lower third of the posterior surface of the body of the sternum, from the posterior surface of the xiphoid process, and from the sternal ends of the costal cartilages of the lower three or four true ribs. Its fibers diverge upward and lateralward, to be inserted by slips into the lower borders and inner surfaces of the costal cartilages of the second, third, fourth, fifth, and sixth ribs. The lowest fibers of this muscle are horizontal in their direction, and are continuous with those of the Transversus abdominis; the intermediate fibers are oblique, while the highest are almost vertical. This muscle varies in its attachments, not only in different subjects, but on opposite sides of the same subject. [WP,unvetted]. The atlas records it as a muscle at the organ scale in the human body.

Where the transversus thoracis is

It sits in the thorax and trunk, within the muscular system. Positioned deliberately as part of this species body plan.

What the transversus thoracis connects to

The atlas records 3 typed relationships for it, across 3 kinds of connection. a kind of chest muscle.

Supply and innervation

Innervation: intercostal nerve.

Source

Uberon multi-species anatomy ontology (Mungall et al.), CC BY 4.0. Term UBERON:0002404, version 2026-06-19, retrieved 2026-08-24. Licence: CC-BY-4.0.

• A kind of: chest muscle.
• Innervated by: intercostal nerve.
• contains: skeletal muscle tissue of transversus thoracis.

Questions

Where is the transversus thoracis?

It sits in the thorax and trunk, within the muscular system. Positioned deliberately as part of this species body plan.

What does the transversus thoracis connect to?

A kind of: chest muscle.

Is the transversus thoracis the same in other species?

Leumas holds the same relationship vocabulary for every species it carries, so where another dataset records this structure you can put the two side by side on /compare.