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Sesamoid bone

Medically Reviewed by Anatomy Team

  • Last updated on January 17, 2025

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Sesamoid bones are small, round bones that are embedded within tendons or ligaments.[7] These bones are found in various locations throughout the body, but they are most commonly found in the hands and feet. Sesamoid bones serve a number of important functions, and they can be of clinical significance in certain situations.

Structure

Sesamoid bones are small, usually less than one centimeter in size. They are round or oval in shape and are composed of spongy bone surrounded by a thin layer of cortical bone. They have a smooth surface and are surrounded by a thin layer of connective tissue called the periosteum.

Sesamoid bones are not attached to any other bones and are free-floating within the tissue in which they are located.[5] They are held in place by the surrounding tendons or ligaments, which provide support and stability.

Location

Sesamoid bones are found in various locations throughout the body, but they are most commonly found in the hands and feet.[2] In the hands, sesamoid bones are found in the thumb and the fingers, and in the feet, they are found in the big toe and the heel.

Other common locations for sesamoid bones include the knees, the wrists, and the elbows.[1] However, sesamoid bones can also be found in less common locations, such as the shoulder, the hip, and the pelvis.[4]

Function

Sesamoid bones serve a number of important functions in the body. They are thought to act as pulleys, helping to change the direction of force and allowing for greater movement and flexibility.[3] They also help to distribute weight and reduce stress on the surrounding joint.

In the hands and feet, sesamoid bones help to improve the grip and stability of the joints. They also help to absorb shock and protect the surrounding joint from excessive wear and tear.[6]

Clinical Significance

Sesamoid bones can be of clinical significance in certain situations. One common condition affecting sesamoid bones is sesamoiditis, which is inflammation of the sesamoid bones. This condition is often caused by overuse or injury and can lead to pain and swelling in the affected area.[8]

Another condition affecting sesamoid bones is fractures, which can occur as a result of trauma or overuse. Sesamoid fractures can be difficult to diagnose because they are small and often not visible on x-rays. Symptoms of a sesamoid fracture may include pain, swelling, and difficulty moving the affected joint.

In some cases, sesamoid bones may need to be surgically removed if they are causing pain or other problems. This procedure, called a sesamoidectomy, is generally considered a last resort and is only performed if other treatment options have been unsuccessful.

References

  1. Gray, H., & Standring, S. (2020). Gray’s Anatomy: The Anatomical Basis of Clinical Practice (42nd ed.). Elsevier. ISBN 978-0702077050.
  2. Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2017). Clinically Oriented Anatomy (8th ed.). Wolters Kluwer. ISBN 978-1496347213.
  3. Drake, R. L., Vogl, A. W., & Mitchell, A. W. M. (2020). Gray’s Anatomy for Students (4th ed.). Elsevier. ISBN 978-0323393041.
  4. Marieb, E. N., & Hoehn, K. (2018). Human Anatomy & Physiology (11th ed.). Pearson. ISBN 978-0134580999.
  5. Netter, F. H. (2018). Atlas of Human Anatomy (7th ed.). Elsevier. ISBN 978-0323393225.
  6. Tortora, G. J., & Derrickson, B. (2020). Principles of Anatomy and Physiology (16th ed.). Wiley. ISBN 978-1119662686.
  7. Palastanga, N., & Soames, R. (2011). Anatomy and Human Movement: Structure and Function (6th ed.). Elsevier. ISBN 978-0702035531.
  8. Rohen, J. W., Yokochi, C., & Lütjen-Drecoll, E. (2015). Color Atlas of Anatomy: A Photographic Study of the Human Body (8th ed.). Lippincott Williams & Wilkins. ISBN 978-1451193183.