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Metatarsal 3


Type

long

Description

The five metatarsal bones are each a little different, but they share features of their anatomy in common. They have long slender shafts, the first being more stocky than the others. The shafts have a prismatic shape in cross-section. They are convex dorsally and concave on their plantar surfaces. The shafts expand into somewhat rectangular bases at their proximal ends and rounded heads at their distal ends. The first and fifth metatarsal bases are marked by the presence of tubercles placed in a proximolateral position. The third metatarsal is a little shorter than the second metatarsal.

Etymology

Metatarsal comes from the Greek prefix meta- denoting over or beyond and tarsos. The term tarsos is directly translated as a flat wicker basket. It later referred to any broad, flat surface. Early Greek physicians applied the term to the flat of the foot, to which we still apply it today. Therefore, metatarsus is the region just beyond the flat of the foot.

Articulations

The third metatarsal articulates with four bones: the lateral cuneiform bone, the second metatarsal, the fourth metatarsal, and the proximal phalanx. It forms a triangular surface for articulation with the lateral cuneiform proximally. On either side of its proximal base it forms small articular facets for the neighboring metatarsal bones. Distally it forms a smooth, rounded head for articulation with the third proximal phalanx.

Ossification

The third metatarsal bone emerges from a primary center that arises during the ninth to tenth week of uterine life. This center progresses to define a base and shaft at birth. A second center arises at the distal end forming a head sometime during the fifth to eighth year. The two centers unite between the eighteenth and twentieth year.

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