Bone tissue is classified as compact or spongy according to the size and distribution of the open spaces in the bone tissue. Compact bone tissue is hard or dense with few open spaces. Compact bone tissue provides protection and support. Most long bones consist of compact bone tissue. In contrast, spongy bone tissue is porous with many open spaces. Spongy bone tissue consists of an irregular latticework of thin needlelike threads of bone called trabeculae (from the Latin trabs, meaning “beam”). Most flat, short, and irregular shaped bones are made up of spongy bone tissue.