bone....help

[Amy]

I read a small paragraph about 'Appositional Growth' which i do not
understand:

'As new bone tissue is deposited on the outer surface of bone, the bone tissue
lining the medullary cavity is destroyed by osteoclasts in the endosteum. In
this way, the medullary cavity enlarges as the bone increases in thickness'.

I thought that the bone tissue lining of the medullary cavity was the endosteum?

[Dr.Stein]

Yes, it is. Inside, endosteum or internal periosteum is 'eaten' by osteoclast to enlarge the bone cavity. Meanwhile, deposistion happens outside to make a tought bone wall.