Second Metacarpal

What Constitutes the Second Metacarpal Bone

The 2nd metacarpal is the elongated bone linked with the index finger, participating in the formation of the human palm with the other four metacarpals [1]. It holds the distinction of being the longest among the metacarpals [7] and is comprised of a head, shaft/body, and a base [2].

Where is its Position

Situated between the distal carpal row and the second proximal phalanx, it is flanked by the first and third metacarpals [6].

Second Metacarpal

Growth and Ossification Process

The metacarpal bone of the index finger has two ossification centers, one for the shaft and another for the head. It is the first among the metacarpals to commence ossification, which begins at the middle of its shaft around the 8th or 9th week of fetal development. The head ossification typically begins around the third year of life [3].

X-Ray Image of the Second Metacarpal

Structure of the Index Finger’s Metacarpal Bone: Surfaces and Articulations

The proximal end of this bone has a convex, notch-shaped surface, forming articular facets for the distal carpal bones trapezium, trapezoid, capitate, and, laterally, the second metacarpal. At its distal end, it articulates with the proximal phalanx of the index finger (second proximal phalanx) [4].

Fractures of metacarpals are among the most prevalent types of bone fractures, although fractures of the second metacarpal are infrequent. Palm bone fractures can be categorized into base, shaft, and head fractures (comparatively rare), with the head fracture of the second metacarpal being one of the most common sites [5].

Carpometacarpal arthritis is a condition likely to impact the joint between the second metacarpal and the bones of the distal carpal row. Nonetheless, it is not as prevalent as arthritis in the thumb CMC joint.


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