Final answer:
The medullary cavity is a hollow region in the shaft of long bones that is filled with yellow marrow. It plays a role in bone growth, repair, and remodeling through a process called modeling.
Step-by-step explanation:
The medullary cavity is a hollow region found in the diaphysis (shaft) of long bones. It is filled with yellow marrow, which stores fat. The function of the medullary cavity is to provide a space that allows for bone growth, repair, and remodeling. During bone growth, bone is resorbed on one surface and deposited on another, a process known as modeling.