Hallux sesamoid

Assoc Prof Craig Hacking and Dr Henry Knipe et al.

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

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 and are embedded within the substance of the medial and lateral slips of the tendon of the flexor hallucis brevis muscle respectively 1. They are usually 1.3 cm long x 0.3 cm wide 2. The medial sesamoid is generally larger than the lateral seasmoid. 

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

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

  • cartilaginous dorsal surface articulates with the grooved undersurface of the first metatarsal head
  • intersesamoid ligament:
    • connects the two hallux sesamoids strongly to form one functional unit 2

    • 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
  • plantar digital nerves
  • occurs between 8-10 years of age 1
Anatomy: Lower limb

Anatomy: Lower limb

Article information

rID: 26894
Section: Anatomy
Synonyms or Alternate Spellings:
  • Hallux sesamoid bone
  • Hallux sesamoid bones
  • Hallux sesamoids
  • First metatarsal sesamoid
  • Sesamoid of flexor hallucis brevis

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Cases and figures

  • Case 1: bipartite lateral and normal medial
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  • Case 2: hallucal and lesser metatarsal sesamoids
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  • Case 3: fractured lateral and bipartite medial hallux sesamoid bones
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