ON
HARELIP AND CLEFT PALATE.

ON
HARELIP AND CLEFT
PALATE.

BY
WILLIAM ROSE, M.B., B.S.Lond., F.R.C.S.,
PROFESSOR OF SURGERY IN KING’S COLLEGE, LONDON, AND SURGEON TO
KING’S COLLEGE HOSPITAL, ETC.

LONDON:
H. K. LEWIS, 136 GOWER STREET, W.C.
1891.

To the Memory
OF
SIR WILLIAM FERGUSSON, Bart., F.R.S., LL.D.,
SERGEANT-SURGEON TO THE QUEEN; PROFESSOR OF CLINICAL SURGERY IN KING’S
COLLEGE, LONDON, AND SENIOR SURGEON TO KING’S COLLEGE HOSPITAL, ETC.
In Grateful Remembrance
OF HIS
EXCEPTIONAL KINDNESS FOR MANY YEARS
BOTH AS A TEACHER AND PERSONAL FRIEND,
AND
In Humble Recognition
OF HIS
MASTERLY SKILL AS A SURGEON,
THIS SMALL VOLUME IS
AFFECTIONATELY DEDICATED.

PREFACE.

In bringing this book before the notice of the profession I have given the results of my experience, which has now been considerable, in a department of surgery always of special interest to me, and to which I have devoted particular attention. The privilege enjoyed for many years of assisting the late Sir William Fergusson gave me an early insight into these operations, and an unusual opportunity of learning their details at the hands of so distinguished a surgeon. I have endeavoured to make the work as complete as possible, and to bring its contents up to date, and in this am greatly indebted to the assistance of my colleague Mr. Albert Carless, who has not only revised the whole work, indexed it, and seen it through the press, but has also written the chapter on Development. I gratefully acknowledge the kindness I have received from various sources in permitting the use of blocks for illustrations, notably from Mrs. Mason, the widow of the late Mr. Francis Mason, whose work on the subject is well known, from Mr. Oakley Coles, and many others, whose names will be found in the list of illustrations.

17, Harley Street, W.; 1891.

CONTENTS.

LIST OF ILLUSTRATIONS.

ON HARELIP AND CLEFT PALATE.

CHAPTER I.
GENERAL INTRODUCTION.

Harelip—Cleft palate—Frequency—Occurrence in animals—Associated deformities—Median harelip—Facial clefts—Macrostoma—Mandibular clefts—Causes of these deformities.

The congenital fissures and deformities of the mouth and lips form a group which is considerably larger than might be imagined from the scanty notice given them in ordinary text-books; and although many are extremely rare, yet possibly if more attention were drawn to them, fresh cases would be noted and recorded, and the somewhat scanty materials from which we have to work out their development and characteristics would be increased. In order to facilitate subsequent description, I append a classified list of the deformities which we shall pass under notice, premising that the more practical part of this work will be occupied exclusively with two of them.

Six different classes may be described:—

(1) Median harelip (inter-intermaxillary).

(2) Ordinary harelip (intermaxillary).

(3) Facial cleft (maxillo-intermaxillary).

(4) Buccal cleft, or macrostoma (maxillo-mandibular).

(5) Mandibular cleft, or median fissure of the lower lip.

(6) Cleft palate.

Inasmuch as ordinary harelip and cleft palate are the conditions most commonly met with, it will be convenient to describe them first, alluding subsequently to the others.

Harelip.

French, bec-de-lièvre. German, Hasenscharte—or if with complete cleft palate, Wolfsrachen (wolf-jaw).

Fig. 1.—Hare’s lip to show the median cleft in the lower part prolonged upwards into either nostril. (Sutton.)

Harelip is a congenital deformity of the upper lip, characterised by a cleft extending for a variable depth, either through the soft tissues of the lip only, or implicating in addition the alveolus, floor of the nose, and palate. No mention of this condition is made by Hippocrates, Galen, or any of the fathers of medicine; and so far as I can discover the name is first used by Ambrose Paré, who probably initiated the treatment by pin and figure-of-8 suture. The name is really a misnomer, in that the condition (as has been many times pointed out, but notably by Fergusson) does not simulate a hare’s lip except in the fact of being cleft, for the natural cleft in the animal’s lip is always in the median line below, bifurcating above to reach either nostril ([Fig. 1]), whereas in the abnormal human lip the cleft lies to one or the other side. Instances of median defect are known, but they are extremely uncommon, and consist often of more than a simple fissure.

Fig. 2. Fig. 3. Fig. 4.

Fig. 5. Fig. 6.

The deformity may exist as a simple notch in the soft tissues of the lip, unilateral ([Figs. 2 and 3]) or bilateral ([Fig. 4]); when more decided, it may implicate one or both nostrils ([Figs. 5, 6, and 7]). In mild cases the alveolus is intact; in others, cleft, constituting the variety known as alveolar harelip, and the line of fissure may, or may not, extend backwards into the palate. In all cases of double alveolar cleft, the palate is also involved, and the central parts of the lip and intermaxilla tend to project forwards; in the severest forms these portions are completely isolated from the maxillæ, and, supported by the vomer and septum nasi, form a proboscis-like appendage to the end of the nose, which is excessively disfiguring. ([Figs. 7 and 8] illustrate this deformity as seen from the front and in profile.)

The shape of the nose in unilateral harelip is very characteristic, being broad and flattened out from the deficiency of the floor and posterior wall of the anterior nares.

Figs. 7 and 8.—Double harelip with projection of the os incisivum, as seen from the front and in profile. (Fergusson.)

Harelip seems to occur more commonly in boys than in girls. According to Müller, out of 270 cases, 170 were boys, and 100 girls.

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.)

Fig. 10.

Fig. 10.—Complete cleft palate without alveolar or labial deformity; the vomer is separate from the lateral segments. (Mason.)

Fig. 11.—Complete unilateral cleft palate without alveolar deficiency; the vomer is attached to the left palatal segment. (Mason.)

Figs. 12, 13, 14.—Various degrees of simple fissure of the palate. (Mason.)

Not unfrequently the vomer is attached to one of the margins of the cleft, this condition being usually associated with unilateral alveolar harelip. Such attachment always occurs on the side opposite to the fissure in the alveolus; that is to say, since unilateral harelip is more common on the left, the vomer is usually attached to the right side of the cleft. [Fig. 11] indicates the less common condition of attachment of the vomer to the left palatal segment. Rouge[2] and Oakley Coles[3] fully confirm this statement. The cleft may, however, merely implicate the soft and hard palate, leaving the alveolus and lip perfect, and does not then extend further forward than the site of the anterior palatine canal, and is strictly median ([Fig. 12]); or it may be still more limited, involving more or less of the velum, perhaps only the uvula, or extending a variable distance into the hard palate ([Figs. 13 and 14]).

Fig. 15.—Unusual form of cleft involving the alveolar arch, and the anterior portion of the palate only. (Mason.)

Other less common congenital deformities have been recorded, and amongst them may be noted a case lately seen by myself in a girl of four years, in whom there existed an oval opening at the junction of the hard and soft palate, separated by a narrow bridge of normal palatal tissue from a cleft of the posterior half of the velum and uvula, showing intermissions of development; a congenital aperture in the soft palate at its junction with the hard, or in any part of the velum, but with no defect of either uvula or palate bones (Dieffenbach[4]); a defective development of the palate bones alone, the mucous membrane remaining intact from side to side, and hence no cleft resulting (Trélat, Notta, Langenbeck); or again, as in [Fig. 15], a cleft only of the anterior portion of the palate, extending through the alveolus, and for a short distance behind it (Mason[5]). Inasmuch as the union of the two halves of the velum occurs subsequently to that of the alveolar arch, it appears that this last rare defect must have been due to an intermission of development, which was felt only at the anterior portion, whilst that of the posterior part proceeded normally at a later date.

Mason[6] records a curious case worth mentioning of a girl under his care in 1877, who had a fissure extending through the velum, and for a short distance into the hard palate, but there was no trace of uvula on either side, and the soft palate was continuous on both sides with the pharyngeal wall.

The width of the cleft varies as much as the extent, and is a matter of great importance prognostically, as the broader clefts are much more difficult to close. The direction or slope of the segments of the bony palate also differs considerably, in some instances being more or less horizontal and following the normal curve; in others one or both of the segments is much more nearly vertical, a condition which is not at all unsatisfactory, for, as will be explained hereafter, the more horizontal the palatal processes, the more difficult is it to gain satisfactory closure by operation ([p. 65]).

The frequency of the occurrence of harelip and cleft palate cannot accurately be ascertained, inasmuch as statistics are not readily to be found. In the ‘St. Thomas’s Hospital Reports’ the number of malformations of the children born is noted in some of the years. Thus the aggregate number of living children born in their maternity department in the years 1875, 1877-1880, and 1883 was 10,653, and of this number there was only one case of harelip, with two cases of cleft palate, and three of the combined deformity, i. e. about one case in every 1800 infants born; but if the silence of the reports for subsequent years means absence of deformity, then this proportion may be much too great.

On the Continent some old records are obtainable. Thus, according to Grenser, of 14,466 infants born living at the Maternity at Dresden from 1816 to 1864 there were sixteen cases of simple harelip, and nine with fissures of the palate. Credé states that amongst 2044 infants examined at birth, only one case of simple harelip was observed, and one of complete division of the hard and soft palate.

Occurrence in Animals.

These conditions obtain not only in the human subject, but also in animals, though not so commonly.

Thus Sutton figures a right-sided harelip in a slink calf, and mentions a specimen of a harelip in a lamb in the museum of the Odontological Society; and in our museum at King’s College there is a specimen of a right-sided harelip in a kitten with a cleft alveolus, but the palate is intact.

Cleft palate occurs more frequently in animals, particularly in those born in a state of captivity. Thus it appears that from statistics taken ten years ago 99 per cent. of the lion cubs born in the London Zoological Gardens had cleft palates, indicating that either the food-supply of these animals was not all that was requisite for perfect development, or that enforced confinement has a deleterious effect upon the multiplication of the species. It is a curious fact that in the Dublin Zoological Gardens the deformity was rarely noticed amongst the lion cubs, and the reason for this was supposed to be the supply of such food that the mother could eat both flesh and bone. Since the same practice has been followed in London, viz. giving the lions twice a week a young goat which they can eat, bones and all, the proportion of cleft palates in the young subsequently born has become considerably diminished.

Association with other Deformities.

Occasionally, besides the fissured palate or lip, other deformities are noted in the same patient, but not so often as one might be led to expect. Mason records two or three cases as having come under his notice, the coincident deformities being respectively fistulous openings of buccal glands in an everted lower lip, congenital fissure of the lobe of the right ear, congenital talipes calcaneus and hypospadias. Dr. F. Warner records in the ‘Medical Times and Gazette,’ January, 1882, some cases of cleft palate associated with congenital defects of the heart and smallness of head, and also notes in his more recent report[7] that in 117 cases of malformations of the palate, other than cleft, only 42 were not in combination with other defects. Thus in 55 cases there were abnormalities in the shape of the cranium, in 16 cases defective development of the ear, in 12 the existence of an epicanthic fold, and in 15 cases other defects not tabulated.

Clutton[8] records and pictures a curious development of a flap of mucous membrane on the lower lip of a woman with a cleft palate; it was triangular in shape, and with overhanging projecting angles. The teeth in this case were likewise badly developed, and were all extracted at the age of nineteen.

Binet[9] reports a case of an old cured right-sided harelip in a man dead from apoplexy (æt. 53 years) with infantile genital organs.

Broca[10] describes a much deformed fœtus, stillborn at seven months, which he dissected, showing a double harelip and cleft palate, but the os incisivum retained its usual position, thanks to its mucous covering. The dentition,[11] as noticed elsewhere, was also interesting, and the buccal deformity was associated with a congenital diaphragmatic hernia, and an abnormal condition of the heart and great vessels.

Other associated malformations are on record, e. g. an extra thumb on each hand; and Sir Morell Mackenzie has reported a case in which there was a congenital fissure between the arytænoid cartilages with a trilobate epiglottis, occurring in conjunction with harelip and cleft palate.[12]

The remaining deformities to be noticed here are much less common, but demand attention by their rarity and interest, and on account of the light they throw on the embryology of the lip and mouth.

Median Harelip.

This is an exceedingly rare phenomenon, and for long the possibility of the existence of such a condition was doubted. Supposed cases were explained by imagining that from some unknown cause a lateral fissure had been drawn over to the median line. But at the present time there are records of several, mainly, however, in German works; in our own literature there are but few references to the subject. Two varieties of median defect have been described; and the distinction between these has been carefully and thoroughly made by Trendelenburg.[13]

1. Double cleft of the upper lip with failure of development of the intermaxilla. Some half-dozen cases of this are indicated in his work; but perhaps one of the best descriptions is that recently given by Bland Sutton,[14] and from whose paper the accompanying picture is obtained ([Fig. 16]). It occurred in the practice of Mr. Treves, and died within a few weeks of birth. There was a broad median defect, flanked laterally by the curved convex borders of the maxillary processes; the intermaxillæ were entirely absent, and the nose quite flat. In addition to this the eyes were affected with coloboma, the right eye presenting other serious defects. “On examining the child before its death,” the author states, “I felt convinced that there was no ethmo-vomerine plate, and this conviction was strengthened by the peculiar shape of its forehead. When the child died, this opinion was fully confirmed; there was no ethmo-vomerine plate, consequently no nasal septum, and what is more important, the premaxillary bones were absent.”

Fig. 16.—Median harelip showing total absence of the central portion of the upper lip and of the intermaxillæ, and flattening of the nose from absence of the ethmo-vomerine plate. (Bland Sutton.)

But according to the cases reported by Trendelenburg the defects do not stop here. There is usually in addition a broad median palatal cleft, and an absence of nasal bones and muscles; but Kundrat records two cases where the palatal processes of the superior maxillæ and palate bones were well developed, and united in the middle line. The skull itself has been found defective occasionally, the whole cranial portion being small, and the lamina cribrosa and crista galli of the ethmoid absent; in place of these was a fossa between the orbital plates of the frontal bone with no bony basis, but only dura mater covered with mucous membrane. No openings for the passage of the olfactory nerves were found.

Hadlich has also described changes in the brain in two cases occurring in Langenbeck’s clinique, consisting mainly in the amalgamation, more or less, of the two hemispheres; the corpora striata and optic thalami were united in the middle line, and the third ventricle, fornix, corpus callosum and olfactory nerves were absent. It is interesting to note the association of such an abnormal fusion of the lateral parts of the brain in the median line with the defective development of the median parts in the skull and face.

But the separation of the facial elements is not always maintained; sometimes they fall or are drawn together by the united palate, resulting in the so-called congenital atresia of the nose (“angeborene Atresia der Choanen”), cases of which have been recorded by Luschka, Bitot and Engel. The latter states that in an infant’s skull examined, only 2 or 3 mm. of space existed between the orbits, and 4 mm. between the optic foramina.

2. True median cleft of the upper lip with development of the intermaxilla is an excessively rare occurrence, but a few cases have been now recorded.

The simplest type consists of a cleft in the soft portions of the upper lip with no other deformity, but a more complete variety of the defect includes a median division of the nose.

Mr. Pitts, in the Medical Society’s ‘Proceedings’ (vol. xii, p. 304), reported a case in a boy aged five months ([Fig. 17]). The cleft was median, extending halfway up to the columna. The premaxilla was centrally grooved but otherwise perfect. The palate was normal.

Fig. 17.—Median harelip, showing a mesial cleft in the soft structures of the upper lip. (Pitts.)

A more aggravated condition has been dissected by Witzel (in the Rostock Collection). Behind the cleft in the upper lip was found a median division of the premaxilla, each half of which was firmly united to the adjacent superior maxilla. The vomer was single, but broader than usual, and the palate cleft throughout; the two halves of the nose were bounded internally by separated plates of the divided cartilaginous nasal septum. There was also a defect of the frontal bone giving rise to a meningocele. This flattening of the nose, combined with separation of the anterior nares, gave such an appearance to the face as seemed to warrant the term “dog’s nose” (Doggennase) which has been applied to it.[15]

Facial Clefts (German, “Schräge Gesichtsspalte”).

Fig. 18.—Oblique facial cleft, or rather cicatricial deformity of face along the line usually traversed by such a cleft. (Tillmanns, after Kraske.)

Fig. 19.—Facial cleft in a child, implicating the lower lid and eye, and with a development of accessory teeth along the cleft margins. (Tillmanns, after Hasellmann.)

Fig. 20.—Double facial cleft with macrostoma. (Tillmanns, after Guersant.)

These are seldom seen, but a sufficient number are now recorded and figured to enable us to study the nature of the defect. Sir W. Fergusson seems the only English surgeon who has observed this rare condition, the majority of recorded cases hailing from Germany or France. As we shall see hereafter, this defect is due to the non-closure of the cleft between the outermost part of the intermaxilla and the maxilla itself, and occupies the position which was claimed up to recent years as that of an ordinary harelip.

In several of the cases noted red cicatrices ([Fig. 18]) rather than actual clefts ([Figs. 19 and 20]) were present. The defect begins at the free margin of the upper lip, and usually at the spot whence starts the ordinary harelip cleft; but occasionally from the angle of the mouth. It then trends upwards and outwards, leaving the nose entire, and skirts round the ala nasi to reach its upper limit at the middle of the lower eyelid which is cleft, or at the inner canthus. The eye itself may show a coloboma iridis, usually downwards and inwards. The facial skeleton may be divided or not; sometimes a large opening into the antrum exists (Hasellmann,[16] Kraske[17]). No incisor teeth are developed on the outer side of the cleft, the first tooth seen being the canine. On the inner border of the cleft lip there is usually a marked frænulum, often smaller, however, than the normal median frænum.

This deformity may be unilateral or bilateral (Guersant, Meckel), more frequently the former; and is not uncommonly associated with macrostoma of the same or opposite side of the face (Guersant, Pelvet[18]), as seen in [Fig. 20].

Albrecht[19] records a most interesting case in a newly born pup ([Fig. 21]) of double clefts extending from the lip margin upwards not only into the nostril, but also towards the eye on either side, i. e. a double associated harelip and facial cleft. The specimen is taken from the Royal Veterinary College of Brussels.

Fig. 21.—Front view of a young puppy’s head from a preparation in the Veterinary College of Brussels, showing double harelip with double partial facial cleft. (After Albrecht.)

a. Central portion of upper lip, corresponding to internal nasal process. b. Ala nasi, corresponding to external nasal process. c. Outer portion of upper lip, from superior maxillary process. d. Harelip cleft. e. Facial cleft.

Fig. 22.—Macrostoma, showing the cleft in the cheek prolonged upwards and backwards by a reddish cicatrix to a lateral loss of substance of the cranial wall. (Sutton.)

Macrostoma

Or commissural harelip (French, bec-de-lièvre genien; German, Quere Gesichtsspalte, Wangenspalte, or Grossmaul) is a less uncommon condition, evidenced by an increased transverse diameter of the mouth. The oral aperture extends into one or both cheeks, and, if unilateral, is more frequently on the right side. The cleft extends upwards and backwards towards the auditory meatus, and sometimes towards the temple to a variable extent. It may merely be manifested by a slight increase in the breadth of the mouth, or may extend to a considerable distance, as in a case reported by Rynd,[20] where the mouth-opening extended as far as the first molar on the right side, and to the last molar on the left. Sutton[21] has published drawings of a child ([Fig. 22]) in which a very large cleft existed, the angles of which gradually passed into a red cicatrix. This scar ended in a gaping recent wound over the temporal region, extending to the dura mater, and through this, after death, the convolutions of the brain were visible. The condition was symmetrical, and he suggests that the wound in the skull was probably brought about during parturition. The same author records a condition the very opposite of this, where the defective closure of maxillary and mandibular processes was reduced to a minimum, the deformity amounting to nothing more than a fistulous opening through the cheek, with a small tumour representing an accessory auricle just in front of the tragus.

Roulland[22] has recently reported an instructive case in which double macrostoma existed with accessory auricular appendages, but this was also complicated with an entire absence of the middle ear and of the Eustachian tube, with defective development and absence of the temporo-maxillary joint on the left side. Such a deformity is probably to be explained by an excessive obliteration or partial development of the maxillo-mandibular cleft at its posterior extremity, and a defective obliteration of the same anteriorly.

Fig. 23.—Double macrostoma, showing the presence of auricular appendages. (Tillmanns.)

Fig. 24.—Macrostoma with auricular appendages. (Fergusson.)

Associated with macrostoma is often to be noticed some abnormal condition of the external ear, either defective development or the production of accessory auricles ([Figs. 23 and 24]). In a case of bilateral macrostoma recently under my own care, there was a well-marked accessory auricle. This complication was first pointed out by M. Debout.

One or two observers (Morgan, Colson[23]) have noticed a small papillary projection on the red margin of the cleft, indicating the position where the true mouth ended, and due to the insertion thereat of the divided orbicularis oris.

For long the very existence of this macrostomatous deformity was doubted, but cases have been recognised more or less since 1715, when Muralt pictured it for the first time. A résumé of all the earlier cases has been made by M. Debout,[24] whilst Roulland[25] and Pilz[26] have gathered together some of the later.

Macrostoma is not only attended by great disfigurement, but is also troublesome from the impossibility of the child retaining its saliva, and the food escaping during mastication. Suckling can be performed if the nurse’s nipple be long, but is difficult otherwise. This deformity is, perhaps, more frequently associated with defective cerebral power than any other of the facial clefts, a large proportion of the subjects having been idiots.

Mandibular Cleft.

This condition is one of the rarest that we have had to describe, so much so that Roux and Cruveilhier denied its existence, and Fergusson had seen but one case. Bouisson[27] in 1840 mentions some three or four earlier cases, and records one that he had seen post mortem himself. Since that date some six or eight instances have been noted, and the latest, with some excellent pictures, is described by Wölfler[28] ([Fig. 25]).

The cleft extends in different cases to a variable extent. Thus Nicati, Couronue, F. Petit, and Ammon saw clefts implicating the lower lip alone. Ribell[29] operated on a cleft extending to the chin, through which the saliva was continuously dribbling. Faucon (1868) and Lannelongue (1879) recorded clefts of the lip and mandible conjoined, and in both cystic swellings (presumably of the dermoid type) were found between the segments. Parisé’s (1862)[30] and Wölfler’s cases were also associated with cleft of the tongue, through its whole thickness in the former, and only at its tip in the latter.

Fig. 25.—Mandibular cleft, showing the divided lower lip, the segments being held together by cicatricial bands. (Wölfler.)

In Parisé’s case the child was fourteen days old. The lower lip was cleft through its whole thickness in the median line. The free edges were rounded as in harelip, and the cleft was continued below as a cicatricial band in the middle line of the neck as far as the sternal notch. The mandible was in two portions, which were separated from one another by a distance of two or three millimetres, bridged across by connective tissue. The tongue was entirely divided, the cleft extending back to the glosso-epiglottic ligament, and downwards between the genio-hyo-glossi muscles; each half was covered throughout with mucous membrane, and was bound to the corresponding side of the jaw by a mucous ligament or frænulum.

As to the ætiology of these defects, but little is known.

Heredity is an undoubted factor in their production, and an investigation of the family history will in many cases elicit a confirmation of such an idea. Thus in two instances in my own practice I have been able to determine that the father, grandmother, and great-grandfather had all suffered from harelip to a greater or less extent. Mason in his book mentions several other illustrations of this fact. Liston operated on four members of one family for harelip. M. Demarquay[31] related a case in the Surgical Society of Paris, in which, from the grandparents downwards, eleven children had been born with harelip. In the ‘British Medical Journal’[32] a correspondent related his own family history, stating that it had occurred in some branch or other for the past hundred years.

An examination of the parents’ mouths should always be made when possible, and very commonly it will be found that one or both possess a short upper lip, and a high arched narrow palate. In others there is a slight groove in the alveolar process between the central and lateral incisors. I have also observed a small symmetrical crease on either side of the median line in the upper lip, indicating a tendency to, if not a natural intra-uterine cure of, a double harelip.

In some instances the deformity dies out of families, possibly from the fact that the defective condition in one parent is remedied by a more perfect development in the other; whilst in others the tendency distinctly increases, and a father or a mother with harelip will beget a family where three out of the four or five children will be similarly affected. By a proper selection of mates this deformity could probably be bred out, as well as bred up to.

The so-called Maternal Impression is looked on, especially by the laity, as another common cause of these deformities. Medical men will usually receive histories of such with a smile of incredulity, and rightly so; but some recorded cases, if true, are so definite that to condemn such an explanation too dogmatically seems scarcely to indicate a scientific spirit. The usual type of history given is that after the mother has seen the defect in the newly-born infant, she looks back over the preceding nine months to see if there were any apparent cause for the trouble, and seeking out particularly some shock or fright produced by seeing something resembling the defect in her infant often selects something trivial and irrelevant. The following authentic case is worthy of mention:[33]

A child was born deformed by a left unilateral harelip. The mother immediately asked to see the infant, declaring she was afraid it was marked, and on seeing it manifested no surprise at the appearance of its lip, stating that when about four months pregnant she received a fright, from the shock of which she had not yet fully recovered. Startled by a boy running almost into her arms, from whose face blood was streaming, she had seen a cut in the left side of the upper lip, extending through its substance into the nostril, laying bare the gums and teeth. She turned faint with fright, and could not banish the thought even after reaching home. The lad was subsequently examined, and the scar of a cut was found in that position.

In spite of such facts, however, one hesitates somewhat in accepting the antecedent alarm and the subsequent deformity in the relationship of cause and effect. The imaginary “maternal impression” probably in nine cases out of ten has nothing to do with the defect; whilst a real “maternal shock” which possibly led to the production of the deformity passes unnoticed. Mr. Carless tells me of a case recently seen by him of a cleft of the soft palate in a child, whose mother, without asking any leading questions, gave a history of a sharp attack of febrile disturbance keeping her in bed two or three weeks at a period when the fœtus could not have been more than two months old. This is the type of maternal shock we should possibly look for, rather than the more out-of-the-way maternal impressions commonly suggested.

The union of the parts entering into the formation of the palate, alveolus, and lip is normally completed by the eighth to the tenth week, and when once this has occurred in these parts no maternal impression (such as seeing a gashed lip) could, as far as we know, bring about a retrogressive change. Should some shock occur to the mother prior to that period, we can fully appreciate the possibility of its interfering with the typical growth of the parts then being produced; and the fact that the due adjustment and union of so many component parts is requisite for the normal development of the mouth and face explains why these defects are relatively so common. That a severe shock to an infant may produce coincidently a lamellar cataract and defective development of dentine is well recognised; that a similar type of shock acting on the mother should result in defective union of parts developing at that period in the fœtus is not strange; but that the real shock and the so-called “Maternal Impression” are one and the same is more than doubtful.

CHAPTER II.
ANATOMY AND PHYSIOLOGY OF THE NORMAL PALATE.

The hard palate—The velum and its muscles—The mucous membrane—The blood supply—The shape and size of the hard palate—Functions.

The palate is a more or less horizontal partition dividing the month from the nasal cavity, and consists of a firm bony plate in front (the hard palate) with a freely moveable membrano-muscular velum behind (the soft palate), which under varying conditions of muscular action can either open or close the communication between the nose and pharynx.

The bony palate forms the vaulted roof of the mouth, the central and posterior parts of which are nearly horizontal; and on all sides, except at the back, it is bounded by the alveolar ridge. Into its formation several bones enter; in the adult skull one usually sees posteriorly a cruciform suture indicating the limits of the superior maxillæ and palate bones; but even in the adult, evidence is forthcoming in the existence of traces of sutures to indicate that the anterior part of the palate is formed independently of the part immediately behind it. Thus Mr. Carless tells me that a cursory examination by him of a few dozen adult skulls picked up at random in the Museum of the College of Surgeons revealed the fact that in quite one half of them traces of sutures could be seen extending outwards from the posterior part of the anterior palatine canal; and a similar examination by him of 40 skulls from the Museum of King’s College of many nations and various ages showed a similar result. In almost all there was distinct evidence of the suture in the median line; in 21, the maxillo-intermaxillary suture was indicated; whilst in 10 skulls, representing the period from infancy to young adult life, both the above were seen in all, and 7 showed traces in addition of a suture placed between them on either side, and which we shall describe hereafter as the endo-mesognathic. Kölliker[34] similarly records that out of 325 adult skulls examined, 96 of them showed definite traces of the maxillo-intermaxillary suture. Albrecht[35] declares that nine tenths of the skulls in the Königsberg and Kiel Museums from children under five years of age reveal the existence of five intermaxillary sutures, proving that there are four separate portions to the so-called intermaxilla. Each portion carries an incisor tooth, and the canine is developed immediately at the junction between the outer portion and the maxilla. Occasionally there are three incisors on each side, the jaw being then called hexaprodontous; the extra tooth is developed from the inner segment of the intermaxilla (or endognathion), the outer segment (or mesognathion) carrying as usual only the lateral incisor. The accompanying illustrations well indicate this arrangement of sutures and teeth ([Figs. 26 and 27]); the importance of these facts will be emphasized later. All traces of the facial aspect of these sutures disappear quite early in life.

Figs. 26 and 27.—Diagrams to represent the normal human upper jaw of a child, with four and six incisors respectively, and also indicating the five intermaxillary sutures. (After Albrecht.)

EG, MG, XG. Endo-, meso-, and exo-gnathion. e. Inter-endognathic suture. f. Endo-mesognathic suture. g. Exo-mesognathic suture. i₁. Central incisor. i₂. Lateral incisor. iₐ. Accessory incisor. c. Canine. m₁. First temporary molar. m₂. Second temporary molar.

The bony surface of the roof of the mouth is perforated by numerous small foramina for the transmission of the nutrient vessels to the body of the bone, pitted for the lodgment of mucous glands, and grooved longitudinally for the transit of vessels. At the postero-external corners the posterior and accessory palatine canals give entrance to the posterior palatine vessels, and nerves; and anteriorly in the median line is the anterior palatine canal transmitting the naso-palatine vessels and nerves.

The soft palate is a moveable curtain, consisting of a membranous expansion or aponeurosis attached to the posterior extremity of the hard palate by firm fibrous tissue. Incorporated with it are five pairs of muscles, controlling its movements; it is covered by a smooth thin mucous membrane, and terminates posteriorly in the uvula. The arrangement of these muscles is important, not only from their normal physiological functions, but also from their irregular action and effects in cases of cleft palate ([Fig. 28]). They may be arranged in groups: two, the levator and tensor palati, form a superior group; the azygos uvulæ is intermediate; and the palato-glossus and palato-pharyngeus form an inferior set. Arising from the extremity of the petrous bone, the levator passes downwards, and spreading out below unites with its fellow in the whole length of the median raphe. The tensor arises from the navicular fossa of the internal pterygoid plate, and after being reflected around the hamular process, its action there being assisted by the interposition of a bursa, is attached to the anterior portion of the aponeurosis and to the hinder part of the bony palate. The combined action of these muscles raises and makes tense the velum, and in addition influences the Eustachian tube; but the levator is by far the more important. The azygoi uvulæ muscles arising from the median raphe and spine of the hard palate descend to the tip of that process, and are thus able to regulate its length.

Fig. 28.—Muscles of palate dissected. The cut represents the posterior nares and upper surface of the soft palate.

a. The levator palati. b. The inner bundle of fibres of the palato-pharyngeus, forming the posterior pillar of the fauces, c. The palato-glossus. d. The tensor palati; the cartilaginous extremity of the Eustachian tube is seen in front of this latter. e. The posterior extremity of the inferior turbinated bone. f. The septum. g g. The uvula on each side stretched apart. (Fergusson.)

The two descending muscles are placed in the pillars of the fauces, forming the lateral prolongations of the velum, and the tonsils lie in a recess between them. The palato-glossi arising from the tongue ascend in the anterior pillars of the fauces, and spreading out on the anterior surface of the velum unite in the median raphe. The palato-pharyngei start from the median raphe in two lamellæ enclosing the termination of the levator muscle; they descend in the posterior pillars of the fauces, and being attached to the pharyngeal wall between the superior and middle constrictors, by their contraction assist in raising the pharynx during deglutition.

The nervous supply of these muscles requires little notice here; suffice it that the superior set and the azygos are supplied by the facial nerve, the inferior set from the pharyngeal plexus.

The mucous membrane of the hard palate is of the usual oral type, and only differs from that of the rest of the mouth in its close attachment to the periosteum, from which in fact it is almost impossible to separate it. It is thick, dense, rather pale and much corrugated, especially in front and at the sides, whilst behind over the velum it is smoother and thinner. In it are many small glands (palatine glands) which extend down to the periosteum. In the median line is a well-marked raphe, extending anteriorly to a prominence indicating the position of the anterior palatine canal. The rugose condition of the membrane over the hard palate is not seen in young children; it supervenes later in life.

The vascular supply of the palate is free and abundant, a circumstance which is of the greatest surgical importance in that it permits of the free detachment of the soft structures from the hard by long lateral incisions, and the necessary manipulation of these in uranoplastic operations without any fear of loss of vitality, provided that the patient’s health and constitution are tolerably sound, and that sufficient pedicle is left in front and behind.

The mucous membrane of the hard palate derives its blood supply from two of the terminal branches of the internal maxillary artery. The naso-palatine descend through the anterior palatine canal, and entering the palate at the incisive foramen (foramina of Stenson) assist in supplying the anterior portion, anastomosing with the terminations of the more important posterior or descending palatine, which find their way to the palate from the spheno-maxillary fossæ through the posterior palatine canals. Each of the latter arteries on reaching the palate sends branches to the velum and tonsils, and its main twig runs onwards in a groove of the bone to supply the mucous membrane and glands of the hard palate and gums. Its usual position is parallel to the alveolar border, and about three quarters of an inch from it; but this varies considerably. The artery can often be felt pulsating as it emerges from the bone, and is very likely to be divided in the lateral incisions made during the operation of uranoplasty; but the knife should be carried external to it, if possible, so that the trunk of the vessel may be preserved in the flap. The bony palate derives its blood supply not only from its lower surface but also from its upper, and hence detachment of the inferior periosteal covering does not lead to death of the bone. The soft palate derives its blood from three sources, viz. the ascending palatine of the facial, the ascending pharyngeal, and the posterior palatine of the internal maxillary. The two former reach it through the sinus of Morgagni, i. e. over the upper border of the superior constrictor muscle, forming loops of anastomosis on its posterior aspect with similar branches on the opposite side; the last supplies the anterior palatal surface.

The normal shape of the palate is a regular arch, bounded laterally by the gums and alveoli into which the teeth are implanted so as to describe a parabolic curve, being normally uninterrupted at any spot by spaces or diastemata. The height and curvature of the palate vary considerably in different individuals, not only from inherited peculiarities, but also from acquired conditions dependent on the teeth. A person with a good set of sound teeth will probably own a regular well-formed palate; whilst if sundry of the upper permanent teeth are lost during the stage of adolescence, the palate is likely to become high and narrow from the falling in of the jaw. This is especially the case if the incisor teeth are lost.

The shape of the palate in a child of two years does not differ so markedly as one would at first expect from that of an adult except in length, and the reason for this is plainly the existence in the latter of three additional teeth on each side. Its increase in length is from 20 to 30 millimetres, whilst its breadth is only augmented by 10 to 15 mm., and this mainly posteriorly. When once the permanent incisors, canines, and premolars are developed, the anterior portion of the palate alters but little in shape, unless any of these teeth be lost, and the gaps not artificially maintained.

Dr. Ehrmann[36] states that the alveolar border in front of the canine teeth forms a nearly regular semicircle, with a posterior transverse diameter of 22-26 mm.; thence the alveoli diverge regularly, adding to the diameter about 2-4 mm. for each tooth. He gives the following measurements as the mean of many observations:

Oakley Coles[37] has carefully investigated the size of the palate in several series of skulls in the Museum of the College of Surgeons, and gives the results as follows:

Of 34 adult skulls of European origin, the average length was 49 mm., the average width at the second bicuspid was 35 mm., and the average height from the margins of the alveoli 9 mm.

Of 32 adult skulls of mixed races, the average length was 54 mm., the width 35 mm., and the height 12 mm.

The frequent association of inherited mental and nervous weakness with a high arched palate is now a well-established clinical fact. Thus Savage states that in “Genetous Idiocy” (i. e. idiocy which starts in fœtal life, and cannot be traced to any specific disease) the palate is usually keel-shaped, the molar teeth being closely approximated; they are also late in appearing and deficient in number. “Although this kind of palate may be present in healthy individuals or in those suffering from ordinary insanity, if it be associated with weak-mindedness or moral peculiarities in youth I believe one is justified in saying that the tendency to moral or intellectual deficiency is congenital.”[38] Only recently Dr. F. Warner has reported[39] to the Psychological Section of the British Medical Association the results of an investigation as to the occurrence of deformities amongst school children, and their relationship to defective vital and mental conditions. Out of 5344 children examined, physical deformity was noted in 399 cases, and of these 274 were boys and 125 girls, i. e. in the proportion 9·8 per cent. and 5 per cent. respectively. It was found that of these 25 per cent. exhibited evidences of low nutrition, 36 per cent. evidences of nervous weakness, and 31 per cent. of mental dulness. 117 cases were noted of deformity of the palate, 77 boys and 40 girls; and of these 35 per cent. gave signs of low nutrition, 39 per cent. of nerve weakness, and 35 per cent. of mental dulness. These defects were more marked and more frequent in the pauper than in the elementary public schools, in the proportion of 4·2 to 2·2. As to the character of the malformations, the following are the numerical statistics: In 105 cases, the palate was arched, narrow, high or vaulted; in 8, it was 𝖵-shaped; in 4 it was of the flat type.

Dr. Langdon Down[40] had previously noticed and pointed out this frequent relationship, remarking that as the result of a large number of careful measurements of the mouths of the congenitally feeble-minded and of intelligent persons of the same age, he found with few exceptions a marked diminution in the transverse measurement between the posterior bicuspids, resulting in an inordinate vaulting of the palate. There was often noticed an actual deficiency in the bony structures of the posterior part of the hard palate, causing the velum to hang down abnormally, interfering with phonation.

The function of the hard palate is mainly mechanical. Acting as a partition between the nasal and buccal cavities, it prevents nasal mucus from falling into the mouth, and, by presenting an opposing surface to the tongue, allows of the production by the latter of the vacuum necessary for suction, and enables the tongue to direct the food towards the alveoli, and to disintegrate soft particles, thus assisting mastication. It is also an accessory to the development of taste by enabling particles to be evenly spread over the back of the tongue. For the production of articulate speech the hard palate is an indispensable factor, and the quality of the voice is much influenced by its contour.

The functions of the soft palate are mainly related to the acts of respiration, deglutition, phonation, and articulation.

1. In respiration.—If the mouth is closed, and the respiration purely nasal, the velum hangs loosely, and allows free passage of air through the posterior nares. If the mouth is open, the velum is raised, and air passes freely through the fauces to or from the larynx. When air passes simultaneously through nose and mouth, the velum hangs in a more or less flaccid condition midway between the two extremes, and sometimes, when absolutely relaxed, vibrates, giving rise to snoring or stertor.

2. In deglutition.—The passage of food into the nose is prevented by the closure of the posterior nares. This is effected by elevation and tension of the velum, the levator and tensor muscles acting in unison, so that its position becomes almost horizontal. The raised velum meets the posterior wall of the pharynx, which advances as the result of the action of the upper horizontal fibres of the superior constrictor, and the closure is completed on either side by the approximation towards the median line of the posterior pillars of the fauces from the action of the palato-pharyngei muscles contained therein. These, acting from the soft palate as a fixed point, and raising the pharynx to grasp the bolus of food, straighten the walls of the sphincter-like isthmus faucium, and so guide the food as down an inclined plane. The tension of the velum also assists in this guidance. That the above is the action of the palatal structures is proved by the results of their imperfect development or paralysis, e. g. in post-diphtheritic paralysis, where the naso-pharyngeal cavities remaining unclosed, food (especially if fluid) regurgitates into the nose.

3. In phonation and articulation.—The soft palate is here of considerable importance, inasmuch as it is needed to cut off the naso-pharynx and nasal cavities from the oral pharynx. When defective or paralysed, a certain amount of nasal resonance is imparted to the voice, which, however, is less noticeable during vocalisation than in articulation. For the production of clear normal voice-sounds it is essential that the separation between nose and mouth should be absolute, except for the sounds m, n, and ng. The American twang is probably due to a slight relaxation of the soft palate, permitting a small percentage of voice-sounds to pass through the nose. Dr. N. W. Kingsley[41] has recently published some excellent diagrams illustrating the position of these parts during the production of definite sounds, and for all, except those mentioned above, the velum is horizontal, and in contact with the posterior pharyngeal wall.

CHAPTER III.
DEVELOPMENT.[42]

Normal development of mouth, face, nose, and teeth—Ossification—Development of intermaxilla; old ideas (Goethe’s, &c.); Albrecht’s theory—Harelip; position of cleft in alveolus, and in lip—Dentition; accessory teeth—Development of other deformities.

Before discussing from an embryological standpoint the various deformities which we have already described, it is essential for us to consider the normal process of development of the parts entering into their formation.

About the end of the third week of intra-uterine life, the anterior cerebral vesicle becomes acutely bent over the end of the notochord, and a marked depression is seen on the ventral aspect of this, constituting what is known as the Stomodæum, or primary buccal cavity. This, however, is formed rather by the outgrowth of surrounding processes entering into the formation of the facial elements than by any definite or distinct involution of epiblast. The cavity is bounded posteriorly and superiorly by the cephalic flexure of the cerebral vesicles, and inferiorly is separated from the cephalic portion of the intestine by a septum. This becomes perforated at a slightly later date (eighth or ninth week), and communication is thus established between the stomodæum and intestine. Anteriorly, the opening is at first stellate in shape ([Fig. 29]), but soon assumes the form of a transverse cleft by the union in the middle line of the first pair of post-oral branchial arches, in which are developed the primary cartilaginous bars on either side, known as Meckel’s cartilage, the anterior part of which goes to form the inferior maxilla, and the posterior part the malleus. The soft parts around develop into the lower portion of the cheek, the lower lip and chin ([Fig. 30]).

Fig. 29.—Head of fœtus, of about 5 weeks, from ventral aspect (after His), showing the primitive stomodæum bounded above by the undivided fronto-nasal process, laterally by the maxillary, and below by the still separate mandibular processes. The quinqueradiate appearance is well represented. (Sutton.)

Fig. 30.—Head of fœtus from ventral aspect of a little later date (6-7 weeks). The mandibular processes have now united; the orbito-nasal fissure has come in contact with the ocular vesicle, and the fronto-nasal process has developed into external and internal nasal (or globular) processes around the nasal fossæ (after His). (Sutton.)

At the same time that this mandibular arch is being developed, other changes are occurring around the upper part of the stomodæum, viz. the shutting off of sacs lined with epiblast to assist in the formation of the organs of special sense, and the outgrowth between them of fleshy processes which by their later amalgamation form the facial skeleton and coverings. Three of these involutions of epiblast occur, two communicating more or less with the stomodæum, viz. the nasal and ocular; whilst the third, or auditory, is separate. Expansions from the cerebral vesicles meet them, and by further changes, unnecessary to particularize here, the organs of special sense are elaborated.

Fig. 31A.—Head of fœtus at a somewhat later date (8 weeks) as seen from the front, showing the nasal and maxillary processes in close apposition, and the clefts between them diminishing in size.

Fig. 31B.—The same, seen from below, the mandibular process having been removed.

i.m. Central portion of fronto-nasal process, m.n.pr. Internal nasal process. pr.gl. Globular process, or the lower rounded extremity of the former. l.n.pr. External nasal process. m.x. Maxillary process. m.n. Mandibular process.

The most anterior of these depressions are the primary Olfactory pits which appear on either side on the lower surface of the wall of the anterior cerebral vesicle at a very early date. They are at first merely depressions surrounded by a raised margin; but subsequently they become pyriform by the extension of the lower end as a groove into the stomodæum. Each pit and groove is bounded laterally by thickened rounded outgrowths developed from a broad median fleshy protrusion from the same part of the cerebral vesicle, the fronto-nasal process; these are termed respectively the external and internal nasal processes, the latter being also named by His the globular processes ([Fig. 30]).

These Globular processes are separated in the median line by a groove which is subsequently obliterated by their amalgamation to form the central portion of the upper lip (“Philtrum” of German authors), and from their deep aspect the inner segments of the intermaxilla (endognathia). Above this groove is a central flattened median portion of the fronto-nasal process, from which subsequently the prominence of the nose is developed ([Figs. 31A, 32, and 33]), a result of the continued growth from its deeper aspect of the ethmo-vomerine plate.

The external nasal process forms the ala nasi and the soft parts in its immediate neighbourhood, extending downwards a little distance, but probably not so far as the red margin of the lip. From its deeper aspect the outer portion of the intermaxilla (mesognathion) is developed, and in it appears the germ of the lateral incisor. It also serves to separate the nasal pit from the second epiblastic intrusion which assists in the formation of the eye. The lower boundary of the naso-orbital fissure which passes from the primary ocular involution to the stomodæum is formed by the maxillary process, which is usually described as an upward extension of the mandibular process, but which probably arises separately as a pre-oral branchial outgrowth. From this is developed the whole of the superior maxilla, except that portion which is intermaxillary, and also the greater part of the cheek.

Figs. 32 and 33.—Later stages of development of fœtal head.

About the sixth week the stomodæum shows signs of division into upper and lower segments by the outgrowth from the deep aspect of each maxillary process of horizontal palatal plates, which by their junction in the median line form the rudiments of the hard and soft palate, separating thus the nasal and buccal cavities. The anterior portion of these unite with the lateral aspects of the deeper parts of the fronto-nasal process, leaving a space of greater or less dimensions in the median line, known as the anterior palatine canal, which serves subsequently for the passage of nerves and vessels, and for the lodgment of the “organ of Jacobson” in animals in which it occurs.

The upper or nasal cavity is again subdivided into lateral halves by the growth downwards from the under surface of the fronto-nasal process of a central vertical septum, to become in time the cartilaginous septum nasi and the bony ethmo-vomerine plate, uniting at its lower border with the primary fleshy palatine processes ([Fig. 34]).

The tongue grows as a fleshy protuberance from the floor of the stomodæum; antero-lateral segments on either side from the conjoined second and third branchial arches unite with a central posterior growth from the tuberculum impar in an inverted 𝖸-shaped manner. At the point of junction of the segments is a depression from which the thyroid gland develops, indicated in later life by the foramen cæcum.

Fig. 34.—Diagrammatic representation of the development of the palatal processes and of the ethmo-vomerine plate, seen in vertical section. (After Gegenbaur.)

a. Ethmo-vomerine plate. b. Palate processes. c. Tongue. d. Buccal cavity. e. Nasal cavity.

Each of these primary epiblastic pits is at a later date almost entirely cut off from its connection with the buccal cavity. The external and internal nasal processes of the fronto-nasal outgrowth unite below the anterior olfactory pits, and thus surround the anterior nasal apertures, and separate the nares from the mouth. The external nasal and superior maxillary processes are also freely amalgamated except along one small deep track, which remains patent to form the nasal duct and lachrymal passages; and probably the internal nasal and maxillary processes unite below the external nasal process to establish the continuity of the red margin of the upper lip. The union of all these various parts has been completed by the sixth to the tenth week of normal fœtal life; the external nasal and superior maxillary processes unite first, and by the sixth week are becoming closely approximated to the central portion of the fronto-nasal process, a time when the palatal processes are only indicated as slight ridges. By the ninth week the alveolus and upper lip are complete, and union of the palate is commencing from before backwards, being usually completed even to an indication of the uvula by the tenth week.

Whilst the later stages of these developmental processes are in progress, points of ossification have been appearing in many places to form the cranial and facial skeleton. A full knowledge of this subject is still unattained, but the researches of Goodsir, His, and others have thrown much light on hitherto dark passages. There are two main sources of origin of the bones of the skull, viz. from cartilage and from membrane, and it is important to appreciate the portions of the skull which originate from each of these sources respectively. The bones laid down primarily in cartilage are mainly those forming the base of the skull and their anterior prolongations. Thus about the fourth week of intra-uterine life the basis cranii consists of a cartilaginous mass surrounding the upper end of the notochord, and prolonged anteriorly around the pituitary fossa as two cartilaginous bars, the trabeculæ cranii, into the fronto-nasal process. From the anterior extremity of this the nasal bones and cartilages are developed, and from the under surface the ethmo-vomerine plate. The transformation of the primordial mesoblastic undifferentiated tissue into recognisable cartilage is occurring from about the fourth or fifth week until the eighth, when ossification at different centres is apparent. To the development of the intermaxilla we shall refer in detail later; suffice it to say here that the ossifying centres appear about the eighth week, and by the twelfth to the fourteenth the whole process is ossified, and the space between the maxillæ closed except posteriorly, where the anterior palatine canal remains permanently patent; the component parts of the bone, however, are not united until a later date. There are two other cartilaginous foci from which ossification ensues, viz. the pterygo-palatine cartilage in the superior maxillary process, a delicate bar from which arise in part the pterygoid and palatine plates; and Meckel’s cartilage in the mandibular process for the production of the mandible and malleus. All the other facial bones are developed from membrane, more or less in connection with these bars. The vomer is ossified from a single nucleus appearing in the upper part of the ethmo-vomerine plate, about the ninth week; from this two laminæ are developed, which, passing downwards and forwards on either side of the middle line, embrace the septal cartilage. The amount of the osseous material increases from behind forwards, until at maturity a median osseous lamina remains which is grooved only anteriorly.

The palate bone develops from a single centre appearing about the eighth week at the junction of the horizontal and perpendicular portions. The superior maxilla is supposed to arise from four separate foci of ossification, viz. for the alveolar arch, for the palate, for the orbito-malar portion, and for the naso-facial segment. All these are united together by the third month.

It is unnecessary here to discuss the development of the teeth beyond stating that the thickening of the epiblast covering the gums, which occurs as the earliest sign of the production of the milk teeth, is to be seen about the forty-fifth day, when as yet there are no signs of ossification of the maxilla, and by two and a half months a distinct involution filled with cells is evident. Calcification commences about the eighteenth week of intra-uterine life, and extending from crown to fang is usually not completed until from twelve to twenty months after birth.

By the fifteenth week of embryonic life preparation is being made for the development of the first four permanent molars, and soon afterwards in the sixteenth week occur the inflections of the mucous membrane giving rise to the enamel organs for the twenty anterior permanent teeth; and from this period until the birth of the infant the germs of the twenty-four permanent teeth are passing through the various stages preparatory to calcification, so that at birth the child has not only twenty milk teeth with calcification nearly complete, but also the germs of twenty-four permanent teeth. Calcification commences in twelve of these latter during the first year of life, viz. in the first molars and the incisors, and spreads from the crown in which it starts to the fang. In the case of the incisors this process is not completed until the tenth year.[43]

The question as to the ossification of the intermaxilla has been purposely omitted hitherto, that the subject and its morphological relationship to congenital deformities might be more fully discussed.

In the time of Galen[44] the presence of the intermaxilla as a separate bone had been demonstrated in apes and lower animals, and its existence in man inferred, although probably not actually seen. This opinion held its ground till the sixteenth century, when Vesalius attacked it, maintaining that no such bone existed in man, and its absence was even claimed as a distinguishing feature from the lower animals. The first to actually discover and notify the separate existence of the bone in the human skull was Dr. Robert Nesbitt,[45] who, in a lecture before the Royal College of Surgeons in 1736, described and figured the suture crossing the anterior part of the palate at all times of life, and maintained that during intra-uterine life each superior maxilla “is generally divided into two distinct parts, the sutural line running from between the dentes canini and incisivi up to the bottom of the nose.” But the merit of appreciating the importance of this fact belongs to Goethe[46] and Vicq d’Azyr,[47] the former of whom, in the year 1779, demonstrated the existence of the intermaxilla in the human fœtus, and, as the outcome of this discovery, promulgated in 1819 the theory that in alveolar harelip the cleft in the alveolus occurs at the maxillo-intermaxillary suture, i. e. between the lateral incisor tooth and the canine. This opinion has been believed and handed down through successive generations of surgeons until the present day, but more recent and exact research has so increased our knowledge that it cannot now be considered correct. Many painstaking embryologists have, during the last ten years, been investigating this subject; but the honour of raising the question as to the morphological position of the cleft in harelip lies with Professor Albrecht of Brussels, who in a masterly series of papers has fully established the fact, observed also by others, that the intermaxilla is not developed en masse, but is formed by the coalescence of four segments, two on either side; and he maintains that the cleft in alveolar harelip lies not between the maxilla and intermaxilla, but between the inner and outer intermaxillary segments. These have been named respectively the endo- and meso-gnathion, whilst the maxilla proper is called the exognathion. According to Albrecht, therefore, the cleft is not situated along the exo-mesognathic, but along the endo-mesognathic suture.

Much controversy has been lighted up by this pronouncement, but here only a few of the points of interest and importance will be discussed.

The development of the intermaxilla from two centres on each side may be accepted as a proven fact. It was first maintained by the late Mr. Callender,[48] who stated that these bones have a lateral wedge-shaped sutural surface, fitting into a groove in either superior maxilla, and that the alveolar processes of the latter extend forwards, forming the anterior walls of the sockets of the central incisors, and so fix the bones in position. A confirmation of the idea that the anterior alveolar walls of the incisor teeth are formed in this way was sought in the well-established fact that these particular parts are very imperfectly developed in those cases of alveolar harelip in which the os incisivum is isolated from the superior maxillæ; but such is probably due to the abnormal condition and position in which the bone is developed, rather than to the loss of the maxillary “clip.” And certainly the most recent researches tend to prove that the maxillæ have no share in the formation of the alveoli of the incisor teeth.

Sir William Turner and other anatomists have fully confirmed this method of development from four ossific centres, and important additions to our knowledge of the subject have been made recently. Thus M. Gilis[49] describes and figures the condition of the palate as seen in a six-months fœtus, where it was clearly demonstrated that the intermaxillary portion formed a sort of lozenge-shaped prism fitting in between the two maxillæ, and consisting of four portions of bone, the sutures between these being perfectly clear and distinct ([Fig. 35]). The posterior extremity of the short axis of the intermaxillary segment corresponds to the anterior palatine canal, and the anterior surface forms the median anterior alveolar border, no process of the superior maxilla closing in the alveoli in front. The upper border of the bone forms the floor of the nasal apertures.

Fig. 35.—Bony palate of a fœtus of six months, showing the development of the intermaxilla in four portions.

a. Endognathion. b. Mesognathion. c. Exognathion. d. Anterior palatine canal. e. Endo-mesognathic suture.[50] f. Exo-mesognathic suture. (After Gilis.)

Biondi, of Breslau,[51] has completed the observations necessary for the establishment of this fact by demonstrating the four actual points of ossification in many fœtal skulls of different dates, which had been specially prepared for the purpose. Moreover, as mentioned before ([p. 27]), traces of the five intermaxillary sutures, when looked for, may be found in many adult and in the majority of young skulls.

The fourfold division of the intermaxilla being granted, it is obvious that a cleft through the alveolus such as that occurring in alveolar harelip happens at one of the two following situations, either along the endo-mesognathic, or through the exo-mesognathic suture, i. e. between the component elements of the intermaxilla, as Albrecht declares, or between the maxilla and intermaxilla, as Goethe suggested—a claim which has been vigorously defended by Kölliker against its newer rival.

The relative position of the clefts is indicated in the diagrams appended ([Figs. 36, 37, and 38]).

Fig. 36.—Diagram representing the old or “Goethe” theory of alveolar harelip, indicating both central and lateral incisors as developed from one intermaxilla on either side, and the alveolar cleft between the maxilla and intermaxilla.

M. Maxilla. IM. Intermaxilla. i₁. Central incisor. i₂. Lateral incisor. c. Canine. m₁. First molar. m₂. Second molar.

Figs. 37 and 38.—Diagrams to represent the “Albrecht” theory of harelip, in conditions where the alveolus contained four or six incisors respectively.

EG. Endognathion. MG. Mesognathion. XG. Exognathion. i₁. Central incisor. iₐ. Accessory incisor. i₂. Lateral incisor. c. Canine. m₁, m₂. 1st and 2nd molars.

Albrecht’s papers on the subject are numerous, and contain a large amount of interesting material which space forbids us to introduce here; and one must refer readers, desirous of knowing more, to the appended list of his chief works.[52] But the arguments in favour of his theory may be briefly stated to be drawn from the following facts:

Fig. 39.—Drawing of an adult upper jaw with right-sided alveolar harelip and cleft palate, and the vomer attached to the left palatal margin. A rudimentary mesognathion bearing the stunted lateral incisor is shown on the outer side of the cleft.

i₁, i₂. Central and lateral incisors, x. Inter-endognathic suture. y. Exo-mesognathic suture. (After Albrecht.)

1. That in cases of alveolar harelip, a small portion of bone has been found in many instances on the outer side of the cleft, quite distinct from the maxilla. This is claimed to be the mesognathion, separated by the cleft from the endognathion, and by a distinct suture from the exognathion. A picture ([Fig. 39]) is appended of an adult skull taken from the museum of the Royal Anatomical Institute of Kiel, which clearly shows a small distinct flake of bone in the required position, extending back as far as the ordinary site of the anterior palatine canal. Such has been also found in children’s skulls, and very distinctly in a series of horses’ skulls with alveolar harelip. (For figures of such, v. ‘Langenbeck’s Archiv,’ xxxi, 2.) But this condition, indicating the distinct entity of the mesognathion, is not very commonly to be demonstrated in human pathology, inasmuch as the suture is early obliterated. But its existence is indicated by the dentition, to which we must now turn.

Fig. 40.—Drawing of a case of double alveolar and palatine cleft with projecting os incisivum, to show the lateral incisor on outer side of the cleft.

i₁, i₂, c, m₁, m₂, represent the alveoli of the teeth as in [Figs. 26 and 27]. v. Vomer. B. Palatal process of superior maxilla united to the meso- and exo-gnathion. A. Os incisivum, consisting of the two endognathia, and bearing the alveoli of the central incisors. (After Albrecht.)

2. That in alveolar harelip there is in a large number of cases a distinct precanine or incisor on the outer side of the cleft. This is well shown in [Figs. 39 and 40]. In the former, an adult skull, the mesognathion is distinctly seen bearing the alveolus of a precanine tooth, the lateral incisor; whilst the central bony portion (the endognathion) bears but the socket for one tooth, the central incisor. The latter is a picture of a child’s skull with double alveolar harelip and cleft palate; the os incisivum is seen separate and projecting forwards at the end of the nasal septum; it bears the sockets of the two central incisors. Outside the cleft the alveolus bears four teeth on either side, viz. two molars, one canine, and one precanine, which we cannot but recognise as the normal lateral incisor. So that the dental formula of the upper jaw might be represented thus:

In normal jaw—CI₂I₁I₁I₂C;

in double alveolar harelip—

CI₂=I₁I₁=I₂C,

where C represents the canine, I₁ and I₂ the central and lateral incisors, and the double lines indicate the position of the clefts. Careful examination of a considerable number of skulls has brought much confirmatory evidence to light, indicating the truth of the above proposition. Thus, to pick out a few facts from the mass of material available:—Sabourand[53] records two cases of unilateral harelip with cleft palate, one of which died at the age of thirty-three days. In each the dentition was typically that described by Albrecht, viz. four teeth on the side of the cleft (two molar, one canine, and one precanine), and six on the opposite (two median incisors, one lateral incisor, one canine, and two molars). Broca[54] has reported a case of a much deformed fœtus stillborn at seven months. In this there was cleft palate and double harelip with the os incisivum freely moveable, but not displaced. The bone was found to consist of two little masses, mobile on each other, and each containing two incisor germs; and on each side external to the cleft there was a precanine similar in shape to the incisors. The middle one of these three incisors was distinctly the least developed.

Again, Sir William Turner[55] has carefully investigated the dentition, as seen in casts obtained from various hospitals, of fifteen specimens of alveolar harelip, eight of which were single left-sided, four single right-sided, and three double clefts. To these he adds the records of forty-nine preparations examined and reported on by Kölliker;[56] we can here, therefore, discuss the dentition of sixty-four cases. They may be divided into two groups:

(α) In which no precanine intervened between the cleft and the canine—thirteen cases.

(β) In which a precanine existed between the cleft and the canine—fifty-one cases.

In not a few instances the os incisivum contained four teeth, and yet a precanine existed external to the cleft, i. e. in hexaprodontous jaws the cleft passed between the middle and outer precanines.

A similar condition is described by Albrecht[57] as occurring in an adult human skull in the museum of the University of Kiel. In this a cleft palate exists, with the fissure extending through the alveolus of the right side, i. e. a right-sided alveolar harelip with cleft palate. The mesognathion is plainly seen on the outer side of the cleft, bearing an incisor tooth. On the inner side of the cleft (i. e. on the left side) are the alveoli for five incisors before reaching the canine socket of the left side, so that here is a skull with six incisor teeth, and with a cleft between the alveoli of the right middle and outer precanines. And not a few similar preparations are indicated by Biondi[58] as occurring in the Berlin and Breslau collections. The condition of parts is represented diagrammatically in [Fig. 38]. Albrecht’s explanation is that the middle of the three precanines, i. e. the outer tooth in the os incisivum, is an accessory development; whilst that on the outer side of the cleft is the normal lateral incisor springing from the mesognathion.

With such facts one necessarily collates the accredited teaching respecting the number and character of the incisor teeth in man.

Normally one finds two incisors on each side, occupying the space between the canines, but it is a fact perfectly well recognised by dentists that occasionally an extra precanine or incisor is present ([Fig. 27]); and very rarely are there more than three incisors on either side. My colleague, Professor Underwood, tells me that once he has seen the cast of a jaw with at least five precanine teeth on one side only, but that was an absolute exception, and only to be explained as a vagary of nature. The more common existence of three incisors can scarcely be placed in the same category, especially when one considers that although not constant by any means throughout the series, yet amongst the mammalia one does find three incisors as an oft-repeated formula; and certainly the typical mammalian dental formula would indicate the occurrence of three incisors on each side. Hence it is possible that the occasional occurrence of three incisors in man is an illustration of the so-called “recurrence to type,” and that, under ordinary circumstances, one incisor has been suppressed; and the majority of anatomists fully concur in the belief that it is the middle one of the three which has disappeared. The occasional failure of the wisdom teeth to erupt, an occurrence which dentists tell us is increasing in frequency, is additional evidence as to the possibility of the disappearance of an incisor.

The accessory tooth in the os incisivum met with in some cases of alveolar harelip is maintained by Albrecht to be a reappearance of this lost middle incisor; and his explanation of such an occurrence seems very feasible, viz. that the existence of the alveolar cleft prevents the naso-palatine artery from anastomosing with the posterior palatine, and thus the vascular supply to the os incisivum is greater than it should be under normal circumstances; hence, there being a superabundance of nutrient material, nature uses such in the restoration of a structural unit ordinarily suppressed. The same fact (viz. the absence of the usual anastomosis) may explain why the mesognathion is (even when demonstrably present) always small and the lateral incisor not infrequently stunted or absent, and so answers the objection to this theory which has been raised on the ground that in cases of alveolar harelip an incisor external to the cleft is not invariably present.

Hence the dental formula in cases of alveolar harelip will vary as follows:

In tetraprodontous jaws—

CI₂=I₁I₁=I₂C,

or

C=I₁I₁=C;

in hexaprodontous jaws—

CI₂=IₐI₁I₁Iₐ=I₂C,

or

C=IₐI₁I₁Iₐ=C,

where Iₐ represents the accessory incisor, the other letters as on p. 51. The former of each of these pairs of formulæ represent the mesognathion and lateral incisor as present, the latter as absent.[59]

Notwithstanding the mass of positive evidence which is steadily accumulating in favour of Albrecht’s theory, there are still some careful observers who will not admit its truth. Some attack it on the ground that the intermaxilla does not consist of four portions (Kölliker, &c.); with such we have already dealt. Others object to it on the ground that any teeth existing external to the cleft are merely accessory teeth, or due to a bifidity of the canine. The arguments with which they support their opinion are derived from the following considerations:

(i) That in normal development accessory teeth do certainly occur, as in the case mentioned above ([p. 53]), whilst in a few instances of abnormality the same condition has been noted (e. g. a few cases recorded by Kölliker;[60] see also [Fig. 19], showing a facial cleft in which several accessory teeth are present along the inner margin). And the explanation given of such facts is that the involution of mucous membrane from which the teeth are developed is continuous along the alveolar ridge, and not localised to the definite spots from which the teeth subsequently erupt. This, however, is merely an opinion still sub judice, and not absolutely proven.

(ii) That in other defects accessory structures are sometimes produced in the neighbourhood, as if Nature, being baulked in her efforts of development at one spot, expends her energies in some less useful addition elsewhere. The accessory auricles and auricular appendages seen in macrostoma are cited as illustrations of this; and any precanine external to the cleft is maintained to be of a similar character. Whilst fully admitting the plausibility of such teaching, I cannot see that it explains such osseous development as occurs in Albrecht’s Kiel skulls, or such a regular appearance of an incisor external to the cleft as that indicated by the figures quoted above. The less frequent existence of an accessory tooth in the os incisivum seems much more readily explicable on such a ground.

To summarize the principal points as to the development of ordinary harelip:

1. That the intermaxilla is derived from the union of four ossific portions, two on either side of the median line, and that these are to be known respectively as the endo- and meso-gnathion, whilst the superior maxilla is termed the exognathion.

2. That these ossific portions are developed from the internal and external nasal projections of the fronto-nasal process respectively, and that ordinarily the central and lateral incisors are developed one from each segment. Occasionally an accessory incisor is developed between the other two from the endognathion.

3. That the external nasal process does not enter into the formation of the upper lip, but terminates superficially in the depression immediately below the ala nasi (see [p. 57]).

4. That simple harelip, where the cleft is limited to the soft parts, is due to the non-union of the superficial portions entering into the formation of the lip.

5. That in alveolar harelip the cleft passes between the endo- and meso-gnathion.

6. That the os incisivum consists merely of the two united endognathia, and normally carries only the two central incisors. Any additional tooth is not the normal lateral incisor, but an accessory one, probably due to the reappearance of an old suppressed member.

7. That any precanine existing on the outer side of the cleft is the normal lateral incisor, springing from the mesognathion; but that the latter portion of bone is rarely seen as a separate entity in human skulls possessing such deformity, from early obliteration of the suture between it and the maxilla, and that it is often badly developed and the lateral incisor stunted or undeveloped from defective vascular supply.

Having entered thus fully upon the question as to the situation of the cleft in alveolar harelip, we must now turn to the consideration of the morphological position of the oblique facial clefts, and their relations to the above.

It has been already pointed out that they commence at about the same spot in the lip margin as ordinary harelip, and thence run upwards and outwards clear of the ala nasi towards the centre of lower eyelid, following along the line of the naso-orbital fissure. Such a condition, coupled with the developmental facts already mentioned, viz. the existence of four segments in the intermaxilla and their relations to the internal and external nasal processes, suggests the following conclusions:

1. That the situation of the cleft in the lip margin is in all probability between the internal nasal and maxillary processes. The truth of this proposition depends on whether or not the external nasal process has any share in the formation of the lip. His, in his diagrams ([Fig. 30]), seems to indicate that it does not, whilst Biondi[61] claims that it does. The fact that these facial clefts commence at about the same spot in the lip margin as do the clefts in harelip seems distinctly to point to the conclusion that the superficial portion of the external nasal process is limited to the development of the ala nasi, and of the soft parts immediately around it. And this opinion goes far to explain the dimpling of the skin around and the consequent definition of the ala nasi.

2. That the situation of the cleft in the alveolus is between the meso- and exo-gnathion, so that the first tooth on the outer side, if developed, will be the canine.

3. That the upper extremity of the cleft should typically be located at either the inner canthus or about the middle of the lower eyelid; but this is not always the case. The association with coloboma iridis is readily explained by an imperfect closure of the choroidal cleft which normally occurs at the lower and inner segment of the globe.

Median harelip in its two forms is readily explained. The true median cleft is due to the non-union of the two globular processes developed from the median portion of the fronto-nasal outgrowth. If prolonged between the bones, it occupies the position of the median inter-intermaxillary suture, and so passes between the two endognathia.

The more serious and complete form is due to the non-development of the globular processes, and hence absence of the central portion of the lip, the endognathia, and of the ethmo-vomerine plate. The contour and size of the alæ nasi in pictures of this deformity suggest strongly that the external nasal processes are developed, but no record of the dentition of these rare cases is to be found.

Macrostoma is due to the non-union of the maxillary and mandibular processes, or possibly in some instances to the imperfect development of the former.

Mandibular clefts are due to the non-union of the separately developed lateral segments of the mandibular process—a deformity which must result from an earlier interference with the normal conditions of development than any of the others. Prof. Wölfler has pointed out that at the period when the branchial arches are being formed, the aortic bulb lies between their ventral extremities, reaching up even as high as the mandibular processes. If from any cause the retrogression of the heart and aortic bulb into the thorax is interfered with, then non-union of the visceral arches may result, and even a cleft mandible may thus be caused. This ingenious theory is stated only to apply to the more severe cases.[62]

Cleft palate is due to non-union of the palatal outgrowths of the maxillary processes. When the cleft extends beyond the anterior palatine canal it may pass along any of the intermaxillary sutures, but usually between the endo- and meso-gnathion on one or both sides. Inasmuch as the palate closes normally from before backwards, it is most common to find the deficiencies at the posterior rather than at the anterior end.

CHAPTER IV.
THE ANATOMY AND PHYSIOLOGY OF HARELIP AND CLEFT PALATE.

Harelip—Effect of labial muscles on deformity—Structure of os incisivum and labial segments.

Cleft palate—Arrangement and action of muscles—Shape of bony segments—Associated irregularity in shape of skull—Physiological effects in nutrition, articulation, &c.

The short description of these congenital conditions given in [Chapter I] must be now supplemented by a little more exact account from an anatomico-physiological point of view.

With regard to harelip, if unilateral, but little remains to be said, except to emphasize the fact that the deformity is not altogether due to loss of substance, but to a considerable extent to the unbalanced action of muscles, the equilibrium of which has been disturbed by the fissure. Thus the orbicularis oris, which should have a sphincter-like action, has its continuity interrupted, so that when contraction occurs, the effect will be to widen and evert the edges of the cleft. The muscles acting upon the corners of the mouth, moreover, will tend to exaggerate the deformity, and thus all such actions as laughing and crying will have a similar result.

The margins of the cleft are rounded, and the red mucous border of the lip passes up for a variable distance on either side, but does not extend to the apex except in very slight fissures. The upper part of the cleft in the more serious forms has its margin formed of skin, a fact which must not be overlooked in planning an operation for its cure, and which will be again alluded to in the next chapter.

The space between the segments of the lip is usually triangular in shape, and like an inverted V; it may or may not communicate with the nostril. In alveolar harelip the alveolus is cleft, as has been already described, along the endo-mesognathic suture; but the floor of the nose is not necessarily implicated.

The line of fissure in many instances passes through the maxillary attachment of the depressor alæ nasi, and the absence of the controlling influence of this muscle is an important element in the production of the broad flattened condition of nostril such a common accompaniment of this deformity, thus affording an explanation of the nasal distortion in cases where the alveolus is intact. If that structure be also implicated, then the floor of the nose will be deficient to a greater or less extent, and the tendency of the nostril to fall away increased.

On raising or making tense either segment of the cleft lip, the existence of strong reflections of the mucous membrane or frænula will become evident, in addition to the normal mesial frænum; these are sufficiently firm to limit the range but not to antagonise completely the action of the muscular contractions already alluded to. Moreover, unless freely divided by undercutting they will effectually prevent by their tension the parts being brought into a state of easy apposition, so necessary in order to gain primary union.

In bilateral or double harelip the maxillary segments on either side correspond in every particular with the outer segment in a unilateral cleft; but the central portion which is continuous with the columna nasi deserves special notice. It is usually ovoid in shape and stunted, appearing as if shrunken upwards from the absence of lateral support; its breadth and length are nearly equal, and there is a small portion of the red labial margin at the lower part. It is attached on its deep aspect to the os incisivum by firm muco-fibrous frænula, and in aggravated cases it appears to project amalgamated with the columna from the tip of the nose, forming the proboscis-like appendage already illustrated ([Fig. 8]).

Fig. 41.—Os incisivum, consisting of two lateral bony segments, each bearing an incisor. (Fergusson.)

The os incisivum has usually a larger superficial area than this “philtrum” of the upper lip, and hence protrudes beyond it in all directions. It forms a projecting tubercle, covered by smooth mucous membrane on its under side, with the central portion of the upper lip attached anteriorly. In a young child it consists of two little portions of bone, imperfectly united together, which in the fœtus are represented by two cartilaginous nodules, mobile on each other, and within each a separate ossific centre; in other words, it is formed by the two endognathia. Inside are found the rudiments of a variable number of teeth; ordinarily in a child’s os incisivum, operated on at the usual age (viz. one to three months), one finds on laying it open the rudiments of four teeth, the temporary and permanent central incisors, arranged in pairs, one above the other. Occasionally, as has been already mentioned ([p. 54]), one finds evidence of the development of another incisor on one or both sides of the projecting tubercle, and directed towards the cleft; but such is usually imperfectly developed and stunted. In fact, amongst all the ossa incisiva removed by Sir William Fergusson and now preserved in King’s College Museum, but few show any traces of the additional incisor, whilst the common arrangement is to find only the two central teeth ([Fig. 41]). In no case is there any evidence of the existence of more than two bony segments.

The anterior wall of the bone is always badly developed, and most commonly when displaced the growth of the whole projection is somewhat impeded, so that it is smaller than in the normal condition.

Its position may vary, being occasionally but little displaced anteriorly, though in consequence of its slight basis of support, viz. the antero-inferior extremity of the vomer, it is generally mobile; bands of muco-fibrous tissue are occasionally seen passing from it to the maxilla under such circumstances. Every variety of anterior displacement is met with, until the severest forms alluded to above are reached. If operative interference be delayed until late in life, the vomer becomes dense and hypertrophied, and the junction with the os incisivum much firmer, increasing the subsequent difficulties and dangers of treatment. More exact details as to the dentition in cases of alveolar harelip have been already given and discussed in a former chapter ([p. 51]). It is interesting to note here, however, that the temporary incisors, both in the intermaxilla and lower jaw, have a tendency to appear earlier than usual; I have many times seen incisors in such cases erupted at birth.