The mid-region of the body, regarded here as equivalent to the metasome, when this is taken to comprise the four anterior leg-bearing segments in cyclopoid copepods, but including the fifth leg-bearing segment in others.

Th1-Th5: 1-5-thoracic segments

Alternative forms for thorax : Th1, Th2, Th3, Th4, Th5, thoracic.