Cage, thoracic means: An enclosure of open work that houses animals is called a cage. Although the thoracic enclosure is a type of animal cage, the biggest “animals” that it can hold are the heart or lungs.
(in Medical Dictionary)

What else does Cage, thoracic mean?

Cage, Thoracic: A structure made up of the thoracic vertebrae, ribs and the sternum breastbone. Costal cartilages attach the ribs and the sternum to it.
(in Medical Dictionary)