vary in their proportions of compact and cancellous (spongy) bone; compact bone is dense and solid in appearance, whereas cancellous bone is characterized by open space partially filled with needle-like structures

vary in their proportions of compact and cancellous (spongy) bone; compact bone is dense and solid in appearance, whereas cancellous bone is characterized by open space partially filled with needle-like structures.

You find cancellous bone in a number of places: the medullary cavity of long bones. And inside short, flat (as pictured above) and irregular bones. Long bone examples are the femur , tibia and humerus. The bones of the skull are flat as well as the sternum. Often marrow taps are done on the sternum.