Unilateral harelip is more commonly met with on the left side than on the right; probably 60-70 per cent. of the cases are left-sided. Thus Müller reports 142 left-sided against 62 right-sided clefts; Mason, out of 65 cases, found 54 to be unilateral, and of these 35 left-sided to 19 on the right; Kölliker mentions that in 165 unilateral clefts, 113 were on the left side, and 62 on the right. My own experience quite coincides with these figures. At present, no satisfactory explanation of this preponderance of left-sided clefts has been given. One solution suggests itself, but we have no facts of importance to support it, viz. that, inasmuch as the majority of people are from heredity or education right-handed, Nature devotes more energy to completing her developmental processes on that side than on the left, and any check to this would be more likely to happen on the left side. It would be valuable and interesting to know in what proportions other unilateral deformities occur on the left and right sides respectively.
Occasionally one sees in the upper lips of children a congenital red line apparently cicatricial, occupying the position of the normal harelip fissure, and which has been supposed to indicate a natural cure of a temporary defect of development. My colleague, Mr. Carless, has recently shown me a case of this character under his care in a child a few weeks old. There was a well-marked red line extending from the lip margin to the nostril; but there was no irregularity in the red border, and no evidence of cicatricial contraction; the tissue of the lip, moreover, seemed quite soft and normal, not fibrous or hard. These points seem to bear out fully Trendelenburg’s opinion[1] that the name “intra-uterine cicatrisation or cure of a harelip” is incorrect, and that such cases are simply due to the raphe of union remaining evident instead of disappearing as usual; and he quotes the normal appearance of the raphes in the scrotum and perinæum as similar conditions. In this child there was no evidence of any groove or depression in the alveolus; but other deformities were present, viz. a very definite post-anal dimple, the cicatrix being adherent to the tip of the coccyx, a slight condition of hypospadias, and a congenital hydrocele. There was no history of deformity in the family, nor of maternal impression.
Cleft Palate.
This is a congenital deformity due to non-closure of the horizontal palatine outgrowths extending inwards from the maxillary processes. The name must not be applied to acquired fissures or defects of the palate due to injury or to disease of the bones later in life. (See [Chap. IX.])
As with harelip, so with cleft palate, the extent of the defect varies greatly in different cases. Thus in the most severe forms, there is a total mesial longitudinal cleft, extending forwards from the tip of the uvula to the level of the anterior palatine canal, thence bifurcating to communicate anteriorly with a double alveolar harelip, the os incisivum or central portions of the intermaxilla being usually displaced forward ([Fig. 9]). Such a condition is known by German authors as “Wolfsrachen,” or wolf-jaw. The vomer descends in the median line usually into close quarters with, but separate from the margins of the cleft, and the os incisivum is attached to its anterior extremity. When the vomer comes far down and is well developed and prominent, and the palatal outgrowths small, the cleft appears to be double, but is not so in reality ([Figs. 9 and 10]).
Fig. 9.
Fig. 9.—Complete cleft palate and double alveolar harelip; simulating a double lateral cleft, due to the vomer being seen free between the palatal segments. (Mason.)
