yoga book / bones / sesamoid bones of the hallux

A medial and a lateral sesamoid bone lie under the head of the metatarsal 1 bone. The flexor hallucis brevis is connected to both sesamoid bones, as well as to the base of the proximal phalanx only slightly further distally. The two sesamoid bones are ovoid and measure approx. 1.3 cm x 0.3 cm. The medial sesamoid bone is also connected to the abductor hallucis (which also inserts a little further at two points on the plantar proximal phalanx, medially and laterally), the lateral sesamoid bone to the adductor hallucis (both heads).

The flexor hallucis longus, on the other hand, runs through the tunnel that the two sesamoid bones pass through to the distal phalanx. This tunnel is connected by a tight ligament (intersesamoideal ligament), which also forms the plantar border of the canal for the tendon of the flexor hallucis longus. They are also connected in a longitudinal direction by collateral ligaments.

The sesamoid bones usually ossify around the 8-10th year of life. They are only supplied proximally with an artery without collaterals, which increases the risk of osteonecrosis. As a normal variant, one or both sesamoid bones may be multipartite.

In addition to fractures, subluxations and dislocations, osteonecrosis, bone inflammation (sesamoiditis) and arthrosis of the joints with the Os metatarsale 1 also occur.

Images

Foot of plantar: Insertions (Linkmap)

Foot from plantar, muscles, superficial (link to linkmap)

Plantar foot bones (link to linkmap)