sesamoid

種子骨

関

sesamoid bone

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/09/13 21:53:14」(JST)

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Sesamoid bone
Sagittal section of right knee-joint.
Sesamoid bones at the distal end of the first metatarsal bone of the foot.
Details
Identifiers
Latin	ossa sesamoidea
TA	A02.0.00.016
FMA	32672
Anatomical terms of bone [edit on Wikidata]

In anatomy, a sesamoid bone (/ˈsɛsəmɔɪd/) is a bone embedded within a tendon or a muscle. It is derived from the Latin word "sesamum" (sesame seed), due to the small size of most sesamoids. Often, these bones form in response to strain. Sesamoids act like pulleys, providing a smooth surface for tendons to slide over increasing the tendon's ability to transmit muscular forces.

Structure

Sesamoid bones can be found on joints throughout the body, including:

• In the knee — the patella (within the quadriceps tendon). This is the largest sesamoid bone.
• In the hand — two sesamoid bones are commonly found in the distal portions of the first metacarpal bone (within the tendons of adductor pollicis and flexor pollicis brevis). There is also commonly a sesamoid bone in distal portions of the second metacarpal bone.
• In the wrist - The pisiform of the wrist is a sesamoid bone (within the tendon of flexor carpi ulnaris). It is not present at birth and generally develops in children ages 9–12.
• In the foot - the first metatarsal bone usually has two sesamoid bones at its connection to the big toe (both within the tendon of flexor hallucis brevis). One is found on the lateral side of the first metatarsal while the other is found on the medial side. In some people, only a single sesamoid is found on the first MTP.

Sesamoid bones over the metatarsophalangeal joint of the great toe of the left foot of an adult woman

• In the neck - Although the hyoid bone is free floating, it is not technically a sesamoid bone. All sesamoid bones form directly from the connective tissue found in tendons and ligaments. By contrast, the hyoid bone forms from a cartilaginous precursor like most other bones in the body.
• In the ear - the lenticular process of the incus is a sesamoid bone and therefore is considered the fourth ossicle of the middle ear.

Clinical significance

• A common foot ailment in dancers is sesamoiditis. This is a form of tendinitis which results from the tendons surrounding the sesamoid becoming inflamed or irritated.
• A bi-partite sesamoid bone is when the sesamoids are in 2 separate entities — usually congenital, but may be related to a history of trauma.
• Sesamoid bones have a very limited blood supply. They are very difficult to heal when not treated early and often lead to avascular necrosis (bone death from lack of blood supply).

Other animals

See also: The Panda's Thumb (book)

In equine anatomy, the term sesamoid bone usually refers to the two sesamoid bones found at the back of the fetlock or metacarpophalangeal/metatarsophalangeal joints in both hindlimbs and forelimbs. Strictly these should be termed the proximal sesamoid bones whereas the navicular bone should be referred to as the distal sesamoid bone. The patella is also a form of sesamoid bone in the horse.

In both the giant panda and the red panda, the radial sesamoid is larger than the same bone in counterparts such as bears. It is primarily a bony support for the pad above it, allowing the panda's other digits to grasp bamboo while eating it. The panda's thumb is often cited as a classical example of exaptation, where a trait evolved for one purpose is commandeered for another.

See also

• Fabella
• Cyamella (bone)

Footnotes

References

• Gray's Anatomy (1918) (Bartleby)

UpToDate Contents

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• 1. 足の種子骨骨折 sesamoid fractures of the foot
• 2. 下肢ランニング障害の概要 overview of running injuries of the lower extremity
• 3. Forefoot and midfoot pain in the active child or skeletally immature adolescent: Overview of causes
• 4. 成人における足の痛みの評価と一般的な原因の診断 evaluation and diagnosis of common causes of foot pain in adults
• 5. 膝蓋骨骨折 patella fractures

English Journal

• The sesamoids of the feet in humans: a systematic review and meta-analysis.

• Yammine K1.
• Anatomical science international.Anat Sci Int.2015 Jun;90(3):144-60. doi: 10.1007/s12565-014-0239-9. Epub 2014 May 7.
• The prevalence and distribution of the sesamoid bones in the feet has been reported in the literature with a high degree of variability. This systematic review aims to provide a better estimate of the frequency of the sesamoids of the foot and their association with variables such as ancestry, gende
• PMID 24801385

• Lateral soft-tissue release through a medial incision: Anatomic comparison of two techniques.

• Simons P1, Klos K2, Loracher C3, Skulev HK4, Gras F5, Hofmann GO6, Fröber R7.
• Foot and ankle surgery : official journal of the European Society of Foot and Ankle Surgeons.Foot Ankle Surg.2015 Jun;21(2):113-8. doi: 10.1016/j.fas.2014.10.004. Epub 2014 Nov 8.
• BACKGROUND: The distal soft tissue procedure is an integral part of hallux valgus surgery, providing soft tissue balance and alignment restoration of the first metatarsophalangeal joint. Various approaches have been established to this end. For techniques that do not include a separate dorsal incisi
• PMID 25937411

• On the development of the patella.

• Eyal S1, Blitz E1, Shwartz Y1, Akiyama H2, Schweitzer R3, Zelzer E4.
• Development (Cambridge, England).Development.2015 May 15;142(10):1831-9. doi: 10.1242/dev.121970. Epub 2015 Apr 29.
• The current view of skeletal patterning fails to explain the formation of sesamoid bones. These small bones, which facilitate musculoskeletal function, are exceptionally embedded within tendons. Although their structural design has long puzzled researchers, only a limited model for sesamoid bone dev
• PMID 25926361

Japanese Journal

• A retrospective study of radiographic abnormalities in the repositories of 2-year-old Thoroughbred in-training sales in Japan

• Journal of Equine Science 27(2), 67-76, 2016
• NAID 130005158520

• 超音波画像診断装置を用いた荷重時の第1中足骨骨頭下部の観察

• 理学療法学Supplement 2014(0), 0442, 2015
• NAID 130005248158

• 種子骨陥入により徒手整復困難であった母趾IP関節脱臼の1例

• 中部日本整形外科災害外科学会雑誌 57(4), 909-910, 2014
• NAID 130004699165

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