Bones consist of two types of tissue: compact bone and spongy, or cancellous, bone. According to class notes from St. Petersburg College, compact bone is the dense, smooth tissue on the outside of the bone. Spongy bone is porous tissue found on the inside of the bone.
According to class notes from Pennsylvania State University, although compact bone appears solid, it actually consists of tightly packed, concentric rings. Blood vessels flow through the center canal. Other spaces within the compact bone, called lacunae, contain osteocytes, a type of cell that assists in bone remodeling. Compact bone tissue provides the strength and structure necessary to prevent bones from breaking, states St. Petersburg College.
Unlike the dense structure of compact bone, spongy bone contains spaces throughout its structure. According to Pennsylvania State University, these spaces contain bone marrow that produces red blood cells for the body. Spongy bone helps to strengthen and support compact bone. SEER training models from the National Cancer Institute state that when stress is placed on the bone, the structures that make up the spongy tissue can realign to provide support.
Together, these tissues make up the bones that provide structure and support to the body, allow muscles to attach and move and protect the body's vital organs and nervous system, according to class notes from Augusta Technical College.