PREDISPOSING CAUSES OF CLEFT PALATE.
Heredity.—The factor of heredity is so well recognized that reference to it here might seem unnecessary. In many cases the physical char acteristics of the parents, normal or abnormal, may be observed in their children. The shape of the head, nose, eyes and other features often resemble those of a parent. The parents may have normal palates while a grandparent or even a great grandparent (and, no doubt, pro genitors further back of whose physical con ditions the parents know nothing), having had the defect, transmitted it to grandchildren or to generations even more distant.
It is thus the law of atavism, or reversion to type, asserts itself. The statement often made by parents, that no ancestor ever had a cleft palate or harelip, applies usually only to their grandparents whom they have known.. As to those further back, as a rule, they know nothing.
Maternal Pre-natal Impressions.— Maternal pre-natal impressions are firmly believed in by many mothers, but proof that cleft palate has been due to such impressions has never been established. At the ninth week of embryonal life, or about the close of the second month, the fissures about the orbit and bones of the palate have been effaced the bones are united. The fright or shock which the mother sustained, to which she ascribes her child's defect, as a rule, occurred subsequent to the time when nature completes the union of the various bony elements which form the palate. After the bones are united no shock, however severe, could separate them.
Defective Defective nutrition or general debility of the mother during the early months of gestation, from any cause, may de lay imion of the palatal plates. Nature does not, as a rule, fail to develop the necessary bone and soft parts to form a normal palate, but it does fail to bring the parts in apposition and urtite them.
Mothers who have suffered from a severe illness during the first 10 weeks of gestation may be so poorly nourished as to bear a child with cleft palate or other deformities. A preg
nancy shortly following the birth of a child often draws heavily upon a mother's vitality, especially if she is not strong, and the enfeebled condition may be followed by deformity of her child.
Intervening Mucosa in Tooth Formation and Supernumerary Dental Rudiments as Factors.— Prof essor Warnekros holds that cleft palate is always due to the rudiments of supernumerary teeth. Among the many causes that have been assigned for failure of union of the palate within the first two months of embryonal life, the one advanced by the late Dr. C F. W. BOdecker is, I believe, most to be relied upon. It is based upon anatomical and physiological grounds. He believed that the membrane from which supernumerary teeth, or any other teeth, were developed prevented union of the bone.
We know that in the formation of the teeth, the mucosa dips deep down into the submucous tissue and forms the epithelial lamina, which contracts into the epithelial cord at the distal end of which the enamel organ is formed. It is too well known to adrnit of discussion that a layer of epithelium, under certain conditions, will form an obstruction to union of the tissues between which it intervenes.
It seems that BOdecker's conclusion, namely, that this epithelial cord delays union of the parts forming the maxillm; and the force ex erted by the tongue and mandible from the beginning of the third month until birth and several months later, would account for the broad separation of the maxillary bones and the cre-ation of the cleft.
Venereal Disease and Uterine inflammation. —The influence of venereal disease on the de veloping child unquestionably causes many physical defects. Likewise, inflammation of the uterus might easily affect the development of the palate as well as other parts.