label: Abnormal metacarpal ossification
label_lc: abnormal metacarpal ossification
description: "Any abnormal process of ossification of the metacarpal bones, which normally are each ossified from two centers: one for the body, and one for the head (metacarpal II,III,IV, and V) and one for the body and one for the base (metacarpal I). At the eighth to ninth week of fetal life, ossification commences in the middle of the body. At the third year the distal extremities of the metacarpals of the fingers and the base of the metacarpal of the thumb begin to ossify; they unite with the bodies at about the twentieth year."