Final answer:
The trabeculae are spicules in cancellous bone that form a network filled with bone marrow and contain osteocytes, making bones lighter and facilitating blood cell formation.
Step-by-step explanation:
The body spicules in cancellous bone that form a meshwork of intercommunicating spaces filled with bone marrow are known as trabeculae.
These trabeculae appear as a lattice-like network of matrix spikes within spongy bone, which not only provides structural support but also makes the bone lighter, thereby facilitating movement. They also contain osteocytes housed in spaces called lacunae, and in some bones, the spaces within this network are filled with red marrow where hematopoiesis (blood cell formation) occurs.