The two types of bone tissue, also known as osseous tissue, are spongy and compact. Compact bone is dense, smooth and defines the exterior shapes of bones. Spongy bone has an asymmetrical, honeycomb-like structure that lines the longer bones and fills the bulky areas of bones.
Spongy bone, also known as cancellous bone, contains trabeculae, which are the open areas that contain red bone marrow. Compact bone is also known as cortical bone. Its primary structures are osteons, cylindrical layers of bone matrix that enclose and protect nerves and blood vessels.
The term "bone tissue" refers to the mineralized structure that makes up the immobile part of the bone. However, bones contain additional structures, such as blood vessels and nerves, which makes them organs.