accessory ossicles

 Os Intermetatarseum

- an accessory bone located between the bases of 2 adjacent metatarsal bones

- most common are os intermetatarseum I (between the bases of the 1st and 2nd

metatarsal bones) and os intermetatarseum IV (between the bases of the 4th and

5th metatarsal bones)

 Os Intercuneiforme

- an accessory bone located dorsally between adjacent cuneiforms

- usually between the medial and intermediate cuneiform bones;

os intercuneiforme I

Os Vesalianum

- an accessory sesamoid located within the tendon of peroneus brevis at its

insertion on the 5th metatarsal tuberosity

- often is a secondary ossification center of the 5th metatarsal tuberosity that did

not fuse

- most easily viewed on anteroposterior or medial oblique radiographic views of

the foot

Os Tibiale Externum

- an accessory sesamoid located within the tibialis posterior tendon at the plantar

aspect of the navicular tuberosity

- best viewed on a lateral oblique radiograph of the foot

- generally also seen on a lateral radiograph of the foot

Accessory Navicular

- an accessory bone located near the navicular tuberosity, usually large and often

a visible prominence clinically

- when present it replaces the navicular tuberosity

- may appear to articulate with the navicular bone as if it was a secondary

center of ossification

- distinguished from the os tibiale externum by larger size

- easily viewed on anteroposterior, lateral and lateral oblique radiographic views

of the foot

Os Supratalare

- an accessory bone located dorsal to the talar neck

 Os Trigonum

- an accessory bone located at the posterior aspect of the talus

- often a secondary ossification center of the lateral tubercle of the talar posterior

process that did not fuse212

- most easily viewed on a lateral view radiograph of the foot or ankle

Secondary Calcaneus / Os Calcaneus Secondarium

an accessory bone located dorsally at the anterior process of the calcaneus

Accessory Sesamoids

- can be found at any or all of the metatarsophalangeal or interphalangeal joints

- rarely a problem except the one located at the interphalangeal joint of the hallux

- often get callous formation and creates pain

- may need to surgically remove it

 Os Peroneum / Os Fibularis

- an accessory sesamoid located within the tendon of peroneus longus muscle

- usually at the peroneal groove of the cuboid (more proximal than os

Vesalianum)

- more easily seen on lateral or medial oblique radiographic views of the foot

Sesamoid of Tibialis Anterior Muscle

located within the tendon of tibialis anterior muscle at the distoplantar edge of

the medial aspect of the medial cuneiform

Sesamoid of Tibialis Posterior Tendon

located plantar to the navicular within the tibialis posterior tendon

Secondary Cuboid / Os Cuboides Secondarium

an accessory bone located plantarly at the calcaneal process of the cuboid