Flat bones are made up of a layer of spongy bone between two thin layers of compact bone. They have a flat shape, not rounded. Examples include the skull and rib bones. Flat bones have marrow, but they do not have a bone marrow cavity.
Silverstein JA, Moeller JL, Hutchinson MR. Common issues in orthopedics. In: Rakel RE, Rakel DP eds. Textbook of Family Medicine. 8th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 30.
Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.