Third Metacarpal

What is the Third Metacarpal Bone?

The third metacarpal (3rd metacarpal) is the bone associated with the middle finger, and it comprises the palm of the human hand in conjunction with the other four metacarpals [1]. It is the second-longest metacarpal [7] and, like the others, has a head, body, or shaft, and base [2].

Where is it Situated?

It is positioned between the distal carpal row and the third proximal phalanx, with the metacarpals of the index finger and ring finger situated on its two sides [6].

Third Metacarpal

Development and Ossification Process

Similar to the other metacarpals (except for the thumb), this one also has an ossification center for its head and another for the shaft [3]. The second and third metacarpals are the first to initiate ossification, with the ossification centers for their shaft starting to appear around the 8th-9th week of fetal development. The head begins to ossify when a child is around 3 years old [4].

X-Ray Image of the Third Metacarpal

Anatomy of the Metacarpal of the Middle Finger: Surfaces and Joints

This metacarpal has multiple articular facets on its base, which is shaped somewhat like a styloid process with an articular facet on the radial-dorsal surface, for articulating with the distal carpal bone capitate. Besides, one articular facet on the medial surface communicates with the metacarpal of the index finger, and another facet on the medial side articulates with the fourth metacarpal [5].

At its distal end, the head of the third metacarpal articulates with the third proximal phalanx [5].

Fracture and dislocation are among the commonplace injuries of the third metacarpal, usually accompanied by other hand bone injuries, resulting from an accident [6]. Arthritis of the third carpometacarpal joint is also relatively uncommon.


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