A - E:

Variations of the processus styloideus of the third metacarpal bone. The third metacarpal (M.C.3) styloid process (black) is an integral part of the metacarpal in 94% of cases (A). It may be found, however, as (B) a portion of the capitate in 3.5%; as (C) a portion of the trapezoid (T) in 0.5%; or (D) as a free ossicle (os styloideum) in 2%. In some cases a separate ossicle may occur together with a distinct process (on the third metacarpal, for example, as in E) in the one hand.

F - K:

Variations at the site of the calceneonavicular bar (modified from Seddon). On the left side the calceneum and navicular are represented as united respectively by F, figrous; G, cartilaginous; and H, bony tissue. On the right side are shown I, a prominent process o nthe calceneum; J a prominent process on the navicular; and K, a separate calcaneonavicular ossicle (calceneum scundarium).

In a similar way a tolacalceneal bridge or a free ossicle (os sestentaculi) may occure between the talus and the sustentaculum tali of the calcaneum.