Morphological association between the muscles and bones in the craniofacial region.

The strains of inbred laboratory mice are isogenic and homogeneous for over 98.6% of their genomes. However, geometric morphometric studies have demonstrated clear differences among the skull shapes of various mice strains. The question now arises: why are skull shapes different among the mice strains? Epigenetic processes, such as morphological interaction between the muscles and bones, may cause differences in the skull shapes among various mice strains. To test these predictions, the objective of this study is to examine the morphological association between a specific part of the skull and its adjacent muscle. We examined C57BL6J, BALB/cA, and ICR mice on embryonic days (E) 12.5 and 16.5 as well as on postnatal days (P) 0, 10, and 90. As a result, we found morphological differences between C57BL6J and BALB/cA mice with respect to the inferior spine of the hypophyseal cartilage or basisphenoid (SP) and the tensor veli palatini muscle (TVP) during the prenatal and postnatal periods. There was a morphological correlation between the SP and the TVP in the C57BL6J, BALB/cA, and ICR mice during E15 and P0. However, there were not correlation between the TVP and the SP during P10. After discectomy, bone deformation was associated with a change in the shape of the adjacent muscle. Therefore, epigenetic modifications linked to the interaction between the muscles and bones might occur easily during the prenatal period, and inflammation seems to allow epigenetic modifications between the two to occur.

Effect of cleft palate repair on the susceptibility to contraction-induced injury of single permeabilized muscle fibers from congenitally-clefted goat palates.

OBJECTIVE: Despite cleft palate repair, velopharyngeal competence is not achieved in approximately 15% of patients, often necessitating secondary surgical correction. Velopharyngeal competence postrepair may require the conversion of levator veli palatini muscle fibers from injury-susceptible type 2 fibers to injury-resistant type 1 fibers. As an initial step to determining the validity of this theory, we tested the hypothesis that, in most cases, repair induces the transformation to type 1 fibers, thus diminishing susceptibility to injury. INTERVENTIONS: Single permeabilized levator veli palatini muscle fibers were obtained from normal palates and nonrepaired congenitally-clefted palates of young (2 months old) and adult (14 to 15 months old) goats and from repaired palates of adult goats (8 months old). Repair was done at 2 months of age using a modified von Langenbeck technique. MAIN OUTCOME MEASURES: Fiber type was determined by contractile properties and susceptibility to injury was assessed by force deficit, the decrease in maximum force following a lengthening contraction protocol expressed as a percentage of initial force. RESULTS: For normal palates and cleft palates of young goats, the majority of the fibers were type 2 with force deficits of approximately 40%. Following repair, 80% of the fibers were type 1 with force deficits of 20% +/- 2%; these deficits were 45% of those for nonrepaired cleft palates of adult goats (p < .0001). CONCLUSION: The decrease in the percentage of type 2 fibers and susceptibility to injury may be important for the development of a functional levator veli palatini muscle postrepair.

Histological analysis of palatopharyngeal muscle from children with snoring and obstructive sleep apnea syndrome.

Obstructive sleep apnea syndrome (OSAS) is an upper airway obstruction that occurs during the sleep. One of the suggested mechanisms involved in this process is a neuromuscular abnormality of the palatal muscles. Whether children with OSAS develop into OSAS adults, or children and adult OSAS are two distinct disorders occurring at different ages are questions to be answered. Here, we made the histological analysis of palatophryngeal muscle in 34 oral-breathing children of both genders, aged 5-12 years old, with hypertrophic tonsils and adenoids. According to the polysomnographic study the participants were divided into children without sleeping disorders (group I) and children with primary snoring (group II) or apnea (group III). The main histological findings were fiber size variability in 70% cases from groups II and III and in 71% from group I; perimysial connective tissue infiltration in 48% children from groups II and III and in 71% from group I; intracytoplasmatic mitochondrial proliferation in 63% cases from groups II and III and in 57% cases from group I. Muscle necrosis was only observed in one case, in association with subglandular inflammation. Others findings observed in all groups included fibers with internal architecture alteration, such as moth-eaten and lobulated fibers, type 2 fiber predominance, and small areas of fiber type grouping. The presence of similar histological findings in the palatopharyngeal muscle in children with primary snoring or apnea but also in children without sleeping disorders indicate that such changes could be a normal histological feature of this muscle rather than a neurogenic or myopathic pathology.

Primary closure of cleft palate: a functional approach.

The role of the different zones of palatal mucosa in maxillary growth are considered and their relevance in surgery of cleft palate discussed. A method of cleft palate repair is described, based on a functional repair of the soft palate, followed by later closure of the hard palate taking into account the anatomy and physiology of the palatal mucosa.

[The eustachian tube in HR computerized tomography. Imaging in the fetus, newborn infant and infant]. / Die Eustachische Röhre in der HR-Computertomographie. Darstellung beim Fetus, Neugeborenen und Säugling.

The lumen of the eustachian tube in foetuses, neonates and infants was demonstrated in cadaver temporal bones immediately after death by air and contrast medium using high-resolution computed tomography with axial and coronal projections. Special consideration was given to the deviation of the tube from the sagittal and horizontal plane and the functional unit consisting of the processes of tensor palatini muscle. At this stage of development the lumen of the cartilaginous portion shows a constant almost circular form, quite unlike the shape in adults. A well developed isthmus between the bony and cartilaginous part is absent. In a 6-month-old foetus the tube is horizontal to the base of the skull, whereas in a 6-month-old infant it forms an angle of approximately 10 degrees. The angle to the sagittal plane changes in the same period from approximately 37 degrees to 40 degrees. In a 6-month-old foetus the fibres of the tensor palatini muscle also run in an almost horizontal line because of the tiny processus pterygoideus and are forced into a steeper direction as a result of its gradual growth. As there is almost no fulcrum function, a tubal opening effect or mechanism of the muscle fibres at this stage of development seems extremely doubtful.

Postnatal development of the eustachian tube and its surrounding structures. Preliminary study.

The postnatal development of the eustachian tube and its surrounding structures (tubal cartilage, tubal gland, tensor veli palatini muscle, and levator veli palatini muscle) was investigated in serial vertical histologic sections from 12 normal temporal bones of individuals whose ages ranged from 39 weeks' gestation to 19 years of age. After projecting tissue sections onto paper and tracing the structures, several measurements were made in order to analyze this development. Findings revealed that the eustachian tube and its accessory structures developed postnatally up to the age of 19 years. The lumen area in a 19-year-old specimen was 4.7 times that of the 1-day-old infant. The development of the tube was greatest in the pharyngeal part. Postnatal development of the eustachian tube appears to be related to growth of the face. The cartilage area in the 19-year-old specimen was 3.6 times that of the 1-day-old infant. The mucosal acinar cells were predominant in infants but no greater than the number of serous acinar cells by the age of 19 years. The areas of the tensor and levator veli palatini muscles in a 19-year-old specimen were 5.1 and 11.1 times, respectively, those of the 1-day-old infant. This preliminary study reports the postnatal development of the eustachian tube and its accessory structures, a subject never thoroughly investigated to date. However, because of the limited number of cases available, further investigation of a greater number of cases should be performed so that the relationship between tubal development and alterations in function that occur with age can be understood clearly.

Anatomic relationshiphs between the human levator and tensor veli palatini and the eustachian tube.

To define the interrelationships of the human levator and tensor veli palatini muscles and the Eustachian tube, fetal heads were serially sectioned and anatomic reconstruction done. Cephalometric points on fetal and adult skulls were compared to evaluate the effect of growth and development on these interrelationships. Based on the results of this study, we propose a mechanism for Eustachian tube function in the normal and in the cleft palate patient. This mechanism offers some explanations for many previously unexplained and paradoxical clinical observations.