Flat Bones

What are Thin Bones

Thin bones are a type of skeletal structures found in the human body, categorized based on their shape. As their name suggests, these bones are thin, flat, and curved. They primarily serve in safeguarding, generating blood cells, and facilitating body movement.

Instances of Thin Bones in the Human Body

Cranial Bones

  • Frontal bone
  • Parietal bone
  • Occipital bone
  • Nasal bone
  • Lacrimal bone
  • Vomer

Upper Limb Bones

  • Scapula

Thoracic Bones

  • Sternum
  • Ribs

Pelvic Bones

  • Ilium
  • Ischium
  • Pubis


  • Sheltering various crucial internal organs — for example, the cranial bones protect the brain, the facial bones guard the eye and nose, the ribs protect the heart and lungs, and pelvic bones protect the reproductive and urinogenital organs
  • Serving as the attachment point for several critical muscles, ligaments, and tendons, which aid in bodily movements


Thin bones consist of a layer of spongy bone enclosed between two thin layers of compact bone. These bones encompass bone marrow but lack a marrow cavity. Similar to other bones, the periosteum covers the outer surface of the bone.

Thin Bones


As previously mentioned, this is the outer membranous covering of the bone, containing blood vessels and nerves. These blood vessels nourish the bone by transporting nutrients to it.

Dense Bone

It forms the upper and lower outer layers of the bone, situated just beneath the periosteum. The dense bone is composed of very hard and compact bone tissue, thereby fortifying the bone.

Cancellous Bone

This innermost layer is lightweight and aids in absorbing sudden mechanical shock. It contains red bone marrow, from which red and white blood cells develop.

The thin bones in the skull share a characteristic feature. They articulate with each other, forming unique immovable joints called sutures. These joints do not fuse until a person reaches about 20 years of age, allowing the brain to grow until then.


  1. Thin bones — Mountsinai.org
  2. Thin bones — Medlineplus.gov
  3. Thin Bones: Structure, Function and Instances — Study.com
  4. Classification of Bones — Training.seer.cancer.gov
  5. Thin bones — Ufhealth.org/flat-bones
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