The shaft of a long bone is known as the diaphysis. The diaphysis is the central, elongated part of the bone, which is primarily composed of compact bone and surrounds the medullary cavity. In contrast, the epiphysis refers to the rounded ends of the bone, which are typically covered with articular cartilage and are involved in the formation of joints with other bones.
The diaphysis plays a crucial role in the strength and support of the bone, allowing it to withstand weight and stress during movement. Understanding the structure of bones, including the difference between diaphysis and epiphysis, is essential in fields like anatomy, medicine, and sports science.