What type of bone is characterized by lower density tissue that fills the ends of long bones?

Spongy bone, also known as trabecular or cancellous bone, is characterized by its lower density and is found filling the ends of long bones as well as the interiors of others. This type of bone has a porous structure, which consists of a lattice-like arrangement of bony struts and trabeculae. The presence of this spongy arrangement allows for the distribution of forces and the reduction of weight, while still providing support.

The role of spongy bone extends beyond structure; it also houses bone marrow and plays a crucial role in the production of blood cells. The lower density of spongy bone compared to cortical bone (the dense outer layer) makes it lighter and more efficient for the overall functionality of the skeletal system. This adaptation is particularly important for facilitating movement and reducing the energy cost of locomotion.

In contrast, cortical bone is the denser, outer layer of bones, providing strength and structure, while dense bone is often a term used synonymously with cortical bone but does not specifically refer to the lighter, internal composition characterized by spongy bone. Yellow bone refers to a type of bone marrow rather than a type of bone structure.