Final answer:
The enlargement of the medullary cavity during bone growth is achieved through modeling, involving osteoclasts resorbing bone on the inner surface and osteoblasts forming new bone beneath the periosteum. This balanced action allows the bone to increase in thickness without becoming unduly heavy.
Step-by-step explanation:
How the Medullary Cavity Enlarges During Bone Growth
The medullary cavity enlarges during growth in thickness via a process known as modeling. This involves the actions of two types of bone cells: osteoclasts resorb old bone from the inner lining of the medullary cavity, while osteoblasts add new bone tissue beneath the periosteum. Appositional growth, the increase in bone diameter, is facilitated by osteoblasts secreting bone matrix at the bone's surface, while osteoclasts break down bone on the inner surface, balancing out the bone's thickening without adding excessive weight.
The remodeling process is aided by the periosteum and the endosteum. The endosteum lines the medullary cavity and is important for bone growth, repair, and remodeling, whereas the periosteum covers the outer surface of bones, providing nutrients through blood vessels and serving as an attachment for tendons and ligaments.
This intricate balance of bone resorption and deposition allows for the continual renewal and enlargement of the medullary cavity, which is essential for healthy bone growth and development.