[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Lower limb](https://durgical.com/en/anatomy/region/lower-limb/) › Sesamoids [Skeletal system](https://durgical.com/en/anatomy/system/skeletal-system/) · [Lower limb](https://durgical.com/en/anatomy/region/lower-limb/) # Sesamoids The foot sesamoids are two pea-sized bones under the big toe joint, inside a tendon; they work like pulleys and take weight. Official name: Sesamoid bones of foot [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=lower_limb&select=sesamoids_foot&side=r) Opens in the Durgical app, no sign-up needed. ## What it is Two small, pea-shaped bones under the head of the first metatarsal, inside the tendons of the flexor hallucis brevis. ## What it does Work like pulleys for the tendons that bend the big toe, and take weight under the ball of the foot. ## Key points - The medial (tibial) sesamoid is larger, takes more load and is injured more often - Bipartite sesamoid vs fracture: bipartite pieces have smooth rounded edges and together are larger than a normal sesamoid; a fracture has sharp, irregular edges - In hallux valgus the sesamoids stay in place while the metatarsal head drifts medially, so they look displaced laterally ## Key facts **Joints with** Plantar surface of first metatarsal head (two grooves) **Landmarks** Medial (tibial) and lateral (fibular) sesamoids in flexor hallucis brevis tendons; FHL tendon runs between them; medial larger, may be bipartite ## Relations **Above** Plantar facets of the [first metatarsal](https://durgical.com/en/anatomy/first/) head, separated by a central ridge **Below** Fat pad and [skin](https://durgical.com/en/anatomy/skin/) of the ball of the foot; the plantar [digital nerves](https://durgical.com/en/anatomy/palmar-digital-nerves/) of the [big toe](https://durgical.com/en/anatomy/great-toe/) close to each sesamoid **Medial** [Abductor hallucis](https://durgical.com/en/anatomy/abductor-hallucis/) joins the medial head of [flexor hallucis brevis](https://durgical.com/en/anatomy/flexor-hallucis-brevis/) at the medial sesamoid **Lateral** [Adductor hallucis](https://durgical.com/en/anatomy/adductor-hallucis/) joins the lateral head of flexor hallucis brevis at the lateral sesamoid; deep transverse metatarsal ligament **In front** Plantar plate and sesamoid–phalangeal ligaments to the base of the proximal phalanx ## How to find it Felt under the first metatarsal head; dorsiflexing the big toe pulls them forward. Tenderness over one sesamoid that moves with the toe helps tell sesamoid pain from MTP joint pain. ## Examination - Passive dorsiflexion of the big toe while pressing on a sesamoid increases the pain of sesamoiditis or fracture ## On imaging The axial (skyline) sesamoid view shows each sesamoid against the metatarsal head; views of the other foot help tell a bipartite sesamoid from a fracture. MRI shows stress reaction and osteonecrosis; CT or bone scan for hidden fractures. ## Common problems - Sesamoiditis: pain under the big toe joint from overuse, common in dancers and runners. - Fractures, including stress fractures. Some people are born with a sesamoid in two pieces, which can look like a fracture. - Pain after turf toe injuries. ## How it is diagnosed A physical exam; X-rays, including special views and a comparison with the other foot; MRI or CT. ## Treatment - Rest, padding to take pressure off, stiff-soled shoes or a boot. - Physical therapy and a gradual return to activity. - Surgery to remove or fix a sesamoid that does not heal (uncommon). ## Clinical notes - Removing one sesamoid can unbalance the toe: removing the medial one favours hallux valgus, the lateral one hallux varus - After turf toe, sesamoids drawn back towards the heel on X-ray suggest a plantar plate rupture - Osteonecrosis shows as fragmentation and sclerosis of one sesamoid, usually in young women ## Anatomical variants - Sesamoids are also often found at the big toe's interphalangeal joint and under other metatarsal heads, most commonly the fifth - The os peroneum in the [fibularis longus tendon](https://durgical.com/en/anatomy/tendon-of-fibularis-longus/) is another foot sesamoid; its frequency varies between populations ## Development Ossify in late childhood, often from more than one centre, which explains bipartite and multipartite sesamoids. ## Related conditions - [Hallux valgus (bunion)](https://durgical.com/en/conditions/hallux-valgus/) ## Test yourself Think of the answer, then tap the question to see it. ## In which tendons do the sesamoids of the big toe lie, and which tendon runs between them? In the tendons of flexor hallucis brevis; the flexor hallucis longus tendon runs between them. ## Which sesamoid of the big toe is injured more often? The medial (tibial) sesamoid: it is larger and takes more load. ## How is a bipartite sesamoid told apart from a fracture on X-ray? Bipartite pieces have smooth rounded edges and together are larger than normal; a fracture has sharp, irregular edges. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/anatomy/sesamoid-bones-of-foot/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** ossa sesamoidea pedis TA2 1514 **Official Spanish (DeCS)** Huesos sesamoideos del pie DeCS D012716 **English (TA2)** Sesamoid bones of foot ## Related - [First metatarsal](https://durgical.com/en/anatomy/first/) - [MTP ligaments and plantar plate](https://durgical.com/en/anatomy/collateral-metatarsophalangeal-ligaments/) - [Flexor hallucis brevis](https://durgical.com/en/anatomy/flexor-hallucis-brevis/) - [Big toe flexor tendon](https://durgical.com/en/anatomy/tendon-of-flexor-hallucis-longus/) - [Big toe](https://durgical.com/en/anatomy/great-toe/) - [Adductor hallucis](https://durgical.com/en/anatomy/adductor-hallucis/) - [Lumbricals](https://durgical.com/en/anatomy/lumbrical-muscles-of-foot/) Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=13097&filter=ths_termall&q=Huesos%20Sesamoideos); [Anatomy, Sesamoid Bones](https://www.ncbi.nlm.nih.gov/books/NBK578171/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/sesamoid-bones-of-foot/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/sesamoid-bones-of-foot/