Through which mechanism are the nutrients brought to the spongy bone?

if i compare compact bone, spongy bones does not contain true Haversian systems instead it  consist of an irregular lattice of thin plates of bone called trabeculae.

The spaces between trabeculae are filled with marrow. The cells of the red marrow are responsible for producing blood. Within trabeculae  lie lacunae which contain osteocytes.

 Blood vessels from the periosteum penetrate through to the spongy bone,  and osteocytes in the trabeculae are nourished directly from the blood circulating through the marrow cavities.