Final answer:
The shaft of a long bone is called the diaphysis. It is composed of dense and hard compact bone, and it contains the medullary cavity, which is filled with yellow marrow.
Step-by-step explanation:
The shaft of a long bone is called the diaphysis. It is the tubular part that runs between the proximal and distal ends of the bone. The diaphysis is made up of dense and hard compact bone, and it contains the medullary cavity, which is a hollow region filled with yellow marrow.