Chap, viii.] THE PALATE. 109 



has been said that the arch is particularly narrow and 

 high in congenital idiots. The outline of this arch is 

 of some moment in operations upon the palate. 



Cleft palate. The palate is often the seat of a 

 congenital cleft. The cleft is precisely in the middle 

 line. It may involve the uvula or the soft palate 

 alone, or may extend forwards and involve the hard 

 palate as far as the alveolus. If it extend beyond the 

 alveolus, the cleft will leave the middle line and will 

 follow the "suture between the superior maxillary bone 

 and the os incisivum, appearing therefore between the 

 incisor and canine teeth. Sometimes at the end of 

 the cleft the upper lip is fissured (hare-lip). Hare-lip 

 is never in the middle line, but corresponds to the 

 suture just named, and is therefore opposite the interval 

 between the lateral incisor and canine teeth. Some- 

 times the cleft in the palate on reaching the alveolus 

 will run on either side of the os incisivum, so that that 

 bone is entirely separated from the superior maxilla. 

 Such cases are associated with double hare-lip, and the 

 os incisivum appears as a nodule attached to the nose 

 and suspended in the centre of the gap. The bone in 

 these cases contains, as a rule, the germs only of the 

 central incisors, the lateral incisors having been lost in 

 the cleft. Hare-lip very commonly exists without any 

 cleft of the palate. Except in very rare instances, a 

 cleft of the hard palate will not exist without a cleft 

 of ' the soft. In some cases the os incisivum may be 

 entirely absent, and then the double hare-lip that 

 exists may appear as a large median gap in the lip. 

 When the hard palate is entirely cleft the edges of the 

 cleft are more or less perpendicular, whereas when 

 the cleft is very slight as regards its antero-posterior 

 length, the palate tends to preserve more or less of its 

 normal curve. 



The buccal cavity, when first formed in the foetus, 

 exists as a wide cleft in the face bounded above by the 



