Answer: The correct answer for the fill in the blank is - inferior; superior.
Diphragm is a thin muscular and membranous sheet like structure that separates thoracic cavity ( chest cavity) from abdominal cavity. It is present below lungs and heart and therefore lies inferior to the thoracic cavity ( chest). It is a primary muscle involved in respiration.
As it separates chest from abdomen, therefore it lies superior or above the pelvic cavity ( present in the pelvic region that lies between abdomen and thighs).
Thus, diaphragm is inferior to the thoracic cavity and superior to the pelvic cavity.
