The diaphysis is primarily composed of what type of bone?

The diaphysis, or shaft of a long bone, is primarily composed of cortical bone, also known as compact bone. This type of bone is dense and forms the outer layer of the bone structure, providing strength and structural support. The compact nature of cortical bone allows it to withstand significant amounts of stress and pressure, which is crucial for the function of long bones during physical activities such as weight-bearing and movement.

Cortical bone's thick layer surrounding the medullary cavity contrasts with cancellous bone, which is found mainly in the epiphyseal ends of long bones and is characterized by a porous, spongy structure. The unique arrangement of cortical bone makes the diaphysis particularly resilient to bending and torsional forces, ensuring the integrity of the bone during various athletic and daily activities.

This composition is vital for providing the necessary leverage and support that long bones require, distinguishing the diaphysis from other types of bone, such as flat or irregular bones, which serve different functions within the skeletal system.