Muscular disorders represent a variety of neuromuscular abnormalities and can be of morphologic/anatomic or functional character. Various types of clefts are examples of morphologic/anatomic abnormalities. A cleft of the lip demonstrates a discontinuity of the orbicularis oris muscle that otherwise has normal fiber composition and normal innervation. Likewise, a cleft of the palate, whether overt or submucous, represents a break in the palatal musculature, but will result in impaired function both of the palate and the eustachian tube.
In individuals with hemifacial microsomia, ot her types of morphologic/anatomic abnormalities are seen. Masticatory and facial muscles may be small or even missing and may have atypical fiber/fat ratio and atypical direction of fibers and abnormal attachments. Individuals with craniosynostosis syndromes present with underdeveloped and malpositioned temporalis as well as tongue and palate tissue abnormalities. They may also have primary muscle function aberrations such as generalized hypotonia of facial and laryngeal muscle. Anatomic/morphologic muscle abnormalities may also be seen in individuals with Nager syndrome, mandibulofacial dysostosis, and Beckwith syndrome, just to mention some of the most common and severe syndromes.
Abnormal muscle function such as hypo- or h ypertonia can be seen in a variety of birth defects and also as post traumatic sequelae. Variations in patterns of muscle use may also be characterized as abnormal and may lead to undesirable morphology of craniofacial skeletal structures.
Characteristic muscular disorders in individuals with craniosynostosis syn dromes and hemifacial microsomia will be discussed.

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Two pairs of monozygotic twins with cleft lip and palate were investigated for craniofacial morphology and arch form of dentition by using cephalometric radiographs and plaster models of dentition.
The zygo sities were determined by means of DNA fingerprints, which are completely specific for use in human identification to analyze patterns of hypervariable DNA fragments. As DNA fragments in the twins were identical, they were diagnosed as monozygotic twins.
‹Twin case 1›Female twin (six years and 11 months cid)
Elder sister: normal
Younger sister: left incomplete cleft lip and palate
‹Twin case 2›
Male twin (six years and 11 months old)
Elder brother: bilateral complete cleft lip and palate
Younger brother: bilateral cleft lip and palate (right complete, left incomplete)
The marked maxillary underdevelopment and posterior displacement and collapse of the upper dental arch in the younger sister (cleft) of twin case 1 suggested an inhibitory effect of maxillary development by environmental factors such as cleft and surgical operation.
The premaxilla of the younger brother (incomplete) of twin case 2 was located slightly upper when compared to that of the elder brother (complete). The upper dental arch of the elder brother (complete) was collapsed in a V-shape. These interpair differences seemed to be due to the degree of cleft and the operation method.
The pattern and the anteroposterior po sition of the mandible were similar between twins of both cases. These results may be due to the young age of twins and no difference of number of teeth with occlusal contact in the molar region between each pair of twins.

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A 69-yearold man with unoperated complete bilateral cleft lip and palate was reported. His cephalometric roentgenograms and maxillary dental cast were analyzed. The results were as follows:
1. The size of the upper part of his face was smaller than the average, wile the width of the nasal cavity was larger.
2. The maxillary depth was great and the maxilla was located anterior to the anterior cranial base.
3. The length of the maxillary arch was longer than the average, however the anterior width of its arch was narrow and the posterior width was average.
4. Although the mandibular body length was within the normal range, the ramus height was shorter and Gonial angle was more obtuse than the average.

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Among cleft palate patients who had been treated at the orthodontic department of Tokyo Medical and Dental University Hospital between the years of 1977 and 1991, about 4.9 % of them were diagnosed as Stickler syndrome or Marshall syndrome. These two syndromes are of autosomal dominant inheritance and their major symptoms are myopia and joint and hearing disorders with characteristic facial appearance. Some cases of myopia will result in retinal detachment and blindness. Since earlier treatment may prevent the progress, clinicians who are treating cleft palate patients would be interested in these two syndromes.
This paper reports on three cases of Stickler syndrome and one case of Marshall syndrome among our own cases. Initial examinations there of were at ages of 11 years 5 months,10 years 5 months,10 years, and 9 years 2 months respectively. Three of these cases were examined before by an ophthalmologist for treatment of myopia gravis and retinal detachment. Another patient had no previous ophthalmological examination, and after being advised at the orthodontic department for ophthalmological examination, this patient was treated to prevent development of retinal detachment.
Since these syndromes have different phenotypes, accumulation of the clinical reports is vitally important.

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Congenital midline fistula of the upper lip is a rare anomaly. Only 25 cases have been reported in literature. We treated two cases with congenital midline fistula of the upper lip. The first case was an eleven-month-old girl and the second case an eight-year-old girl.
Both cases have no other anomalies. The size of the sinus openings were about imm in diameter and 4-5mm in depth. Both openings were blind. The fistula tracts were lined by squamous epithelium with hair follicles, suborificial gland, and sebaceous gland.
Surgical excisions were performed for treatment. These were excised by a vertical fusiform incision in the upper lip. Postoperative healing of both cases was good without the recurrence of the fistula.

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