Which of the following is a thoracic retractor?

The Davidson retractor is indeed a thoracic retractor specifically designed for use in procedures involving the thoracic cavity. Its structure allows for effective retraction of the ribs and surrounding tissues, thereby providing optimal visibility and access to the surgical area. The design is such that it can hold incisions open while minimizing trauma to the muscle and ribs, which is essential in thoracic surgeries.

Retractors in general serve the purpose of holding back tissues during surgical procedures, but the Davidson retractor is uniquely suited for thoracic use due to its shape and the angles at which it can be positioned. This helps surgeons to maintain a clear view of the working field in the thorax, which is crucial for the success of procedures such as lung resections or cardiac surgeries.

The other retractors listed, while being useful in their respective applications, do not have the specific design and functionality that makes the Davidson retractor a preferred choice for thoracic surgery.