diaphysisének
The diaphysis is the shaft or central part of a long bone. It is primarily composed of compact bone, with a hollow, cylindrical cavity called the medullary cavity in the center. This medullary cavity is filled with bone marrow, which in adults is typically yellow marrow, consisting mainly of fat. In children, the medullary cavity contains red marrow, responsible for hematopoiesis (the production of blood cells). The diaphysis provides strength and leverage for the bone and is crucial for locomotion. Its outer layer is covered by a membrane called the periosteum, which contains blood vessels, nerves, and osteoblasts involved in bone growth and repair. The diaphysis develops from the primary ossification center during fetal development. It is characterized by its tubular shape, which is adapted to withstand mechanical stress. The length of the diaphysis is a significant determinant of the overall length of a long bone.