Sesamoids, also known as sesamoid bones, are focal areas of ossification within tendons as they pass over joints 1. They can also occur in ligaments and usually measure a few millimeters in diameter. Their function is purported to be to alter the direction of the tendon and modify pressure, thereby reducing friction 2.
Sesamoid bones of the lower limb include:
See the article on ossicles of the lower limb.
Sesamoid bones of the upper limb are usually found in the hand at the following joints 3:
1st metacarpophalangeal joint sesamoid (two)
- reported incidence of 100% 4
- 1st interphalangeal joint sesamoid
- 2nd metacarpophalangeal joint sesamoid
- 5th metacarpophalangeal joint sesamoid
Less commonly, they may also occur at the 3rd and 4th metacarpophalangeal joints 4.
History and etymology
Sesamoids get their name because the smallest bones resemble sesame seeds in size 1,3.
- 1. Gray's Anatomy: The Anatomical Basis of Clinical Practice. Edinburgh; Elsevier Churchill Livingstone, c2005. ISBN:0443071691. Read it at Google Books - Find it at Amazon
- 2. Rosse C, Gaddum-Rosse P, Hollinshead WH. Hollinshead's textbook of anatomy. Lippincott Williams & Wilkins. (1997) ISBN:0397512562. Read it at Google Books - Find it at Amazon
- 3. Kalantari BN, Seeger LL, Motamedi K, Chow K. Accessory ossicles and sesamoid bones: Spectrum of pathology and imaging evaluation. Appl Radiol. 2007;36(10):28-37. Appl Radiol (full text)
- 4. Chen W, Cheng J, Sun R, Zhang Z, Zhu Y, Ipaktchi K, Zhang Y. Prevalence and variation of sesamoid bones in the hand: a multi-center radiographic study. (2015) International journal of clinical and experimental medicine. 8 (7): 11721-6. Pubmed
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