Final answer:
Cancellous bone is made up of trabeculae, which provide a supportive, lightweight structure and house osteocytes in lacunae; it supports red marrow for hematopoiesis and is crucial for bone remodeling.
Step-by-step explanation:
Cancellous bone, also known as spongy bone, is composed of thin trabeculae that form a three-dimensional network designed to withstand stresses. This lattice-like structure provides strength and lightness to the bone. It contains osteocytes housed in lacunae but does not arrange these in concentric rings as found in compact bone. The trabeculae align along lines of stress to contribute to the bone's robustness. Unlike compact bone, it lacks a system of concentric layers of Haversian canals.
Spongy bone functionally supports and protects the red marrow, where hematopoiesis, the process of blood cell formation, occurs. The presence of osteocytes indicates that bone remodeling can take place as needed. The spaces in the trabeculated network make bones lighter and contain red marrow where hematopoiesis occurs. Unlike compact bone, spongy bone does not contain osteons and has a less dense structure.