Harelip

Harelip is the name applied (from its resemblance to the lip of the hare) to a congenital notch or cleft in the upper human lip, due to imperfect union at an early stage of development of the processes whose formation and fusion separate the mouth from the cavity of the nose. The cleft is not in the middle line, however, as in the hare; but a little to one side (single harelip), or there are two clefts, one on each side (double harelip). This deformity, especially when double, is often associated with a similar defect in the roof of the mouth (cleft palate). The cause of these arrests of development is quite unknown. Harelip is not at all dangerous, but very unsightly. It can be remedied by a surgical operation, which most surgeons prefer to perform during infancy.