Os sesamoideum hallucis

Geteiltes
Sesambein am Metakarpale-1-Köpfchen: Keine Fraktur.
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Ankylose
zwischen Sesambein und Metatarsale 1 Köpfchen. Die Häufigkeit einer solchen Verschmelzung wird mit ca. 4 % angegeben.
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Multipartite
hallux sesamoid • Fractured lateral and bipartite medial hallux sesamoid bones - Ganzer Fall bei Radiopaedia
Hacking C, Fractured lateral and bipartite medial hallux sesamoid bones. Case study, Radiopaedia.org (Accessed on 21 Jan 2023) https://doi.org/10.53347/rID-75507 • CC by-nc-sa 3.0 (modified)
Radiopaedia • CC-by-nc-sa 3.0 • de

The hallux sesamoid bones are paired ossicles of the foot. They function as a fulcrum to increase the leverage of both flexor hallucis brevis and longus.

Gross anatomy

The hallux sesamoids are ovoid-shaped ossicles, separated from each other by the intersesamoidal ridge. There is a medial (tibial) and lateral (fibular) hallux sesamoid, which are embedded within the substance of the medial and lateral slips of the tendon of the flexor hallucis brevis muscle respectively . They are usually 1.3 cm long x 0.3 cm wide . The medial sesamoid is generally larger than the lateral seasmoid and it also occupies a more distal and superficial (plantar) position.

During dorsiflexion of the hallux, the sesamoids lie below the first metatarsal head, offering protection to the otherwise exposed plantar aspect of the first metatarsal head.

Along with the tendons and ligaments listed below, the sesamoid bones form the hallux sesamoid complex.

Articulations
  • cartilaginous dorsal surface articulates with the grooved undersurface of the first metatarsal head
Attachments
  • intersesamoid ligament
    • connects the two hallux sesamoids strongly to form one functional unit
    • forms the floor of the tendinous canal for the tendon of flexor hallucis longus
  • medial and lateral collateral ligaments
  • abductor hallucis tendon: medial aspect of hallux sesamoid complex
  • adductor hallucis tendon: lateral aspect of hallux sesamoid complex

Arterial supply

  • considerable variation but mostly branches from the medial plantar artery but often additional branches from the lateral plantar artery as well as a perforating branch of dorsalis pedis
  • each sesamoid receives a single artery at its proximal pole and there is a general lack of collateralisation, this increases the risk of osteonecrosis and poor fracture healing

Venous drainage

  • veins correspond to the supplying arteries

Innervation

  • plantar digital nerves

Development

Ossification
  • occurs between 8-10 years of age

Variant anatomy

Related pathology

Siehe auch:
Assoziationen und Differentialdiagnosen zu Os sesamoideum hallucis:
geteiltes
Sesambein am Hallux
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