Anatomy of musculus levator veli palatini in the 15-week human fetus

The morphology of musculus levator veli palatini in the 15-week fetus was analyzed using 30-micrometer subserial sections. The sample included 26 specimens, of which 9 each were sectioned coronally and sagittally while 8 were sectioned in the transverse plane. At this stage of development m. levator veli palatini takes a general attachment to the precursor of the petrous part of the temporal bone, and, in some cases, auxiliary attachments to the auditory tube complex were also observed. At its origin, the muscle is located anterior to the tube. It then runs medially, passing beneath the auditory tube prior to entering the velum. As it nears the region of the lateral pharyngeal wall, a small fascicle trails posteriorly and inferiorly to the main muscle mass and occasionally runs into the upper margin of m. constrictor pharyngis superior. The levator muscle is more localized within the velum at this stage of development than it has been reported to be in the adult, being confined here to the central third of the soft palate. Most of the fibers of the muscle appear to form a sling within the central 20% of the velum, although some were seen to take attachment to loose connective tissue and the palatine raphe. Upon its entry into the velum, m. levator veli palatini is intersected vertically by bundles of both mm. palatoglossus and palatopharyngeus.     

Rat eustachian tube synthesizes disaturated phosphatidylcholine

Otitis media results when the eustachian tube fails to adequately ventilate the middle ear. A surface tension-lowering substance may be required for normal tube opening, especially in young children with poorly developed naso-pharyngeal musculature. We report here that rat eustachian tube epithelium synthesizes disaturated phosphatidylcholine, which is recognized as the surface tension-lowering substance of pulmonary surfactant.     

Surgical anatomy of the levator veli palatini: a previously undescribed tendinous insertion of the anterolateral fibers

The purpose of this study was to describe the previously unreported tendinous insertion of the anterolateral fibers of the levator veli palatini (levator) and discuss possible implications for levator function and cleft palate repair. The velopharyngeal anatomy in normal adult cadavers was studied, with histologic confirmation of anatomical findings. These findings were compared with a more limited study of levator anatomy in cleft palates at the time of intraoperative muscle dissection. Just before entering the velum, the levator divides into two parts. The smaller bundle of muscle fibers (anterolateral part) runs anteriorly, close to the lateral pharyngeal wall, and inserts into the palatine aponeurosis through a number of fine tendons. The main part of the muscle runs medially into the velum, where it fans out and forms the levator sling with the contralateral levator. The possible function of the anterolateral part of the levator is discussed. Inadequate release of the tendinous insertions at the time of palate repair may tether the levator anteriorly and compromise muscle retropositioning or may result in splitting of the levator, so that only part of the levator is retropositioned.     

Levator muscle reconstruction: resulting velopharyngeal competence--a preliminary report

The purpose of this study was to evaluate a levator muscle reconstruction procedure on the basis of resulting velopharyngeal competence. Ages of the patients at time of surgery ranged from 5 months to 7 years. The patients were reevaluated postoperatively. If the patients were judged to have normal nasality and no nasal emission, the procedure was considered to have yielded a satisfactory result. If hypernasality and nasal emission resulted, the patients were examined utilizing nasoendoscopy and/or videofluoroscopy. If velopharyngeal incompetence was confirmed, the operative procedure was judged to be successful. Results showed that 60 percent success was achieved. The age range which yielded the best results (73 percent satisfactory) was 37 to 60 months. The data also revealed that the more severe the cleft, the less likely this operative procedure is to produce satisfactory results. The authors recommend continued evaluation of this procedure, preferably utilizing prospective studies.     

Eustachian tube surfactant is different from alveolar surfactant: determination of phospholipid composition of porcine eustachian tube lavage fluid.

Phosphatidylcholine (PC) is the main phospholipid in lung surfactant and, more specifically, dipalmitoyl PC (PC16:0/16:0) is the major surface-active component. Several studies have tentatively shown that eustachian tube lavage fluid (ETLF) contains surface-active material. The aim of the present study was to determine, using electrospray ionization mass spectrometry, whether the phospholipid molecular species composition of ETLF is similar to that of lung surfactant. PC was the main component of both ETLF and bronchoalveolar lavage fluid (BALF). The concentration of phosphatidylethanolamine was higher and phosphatidylglycerol was undetectable in ETLF compared with BALF. The molecular species composition of PC in ETLF was notably different from that of BALF, palmitoyloleoyl PC being the major component. Importantly, given its predominance in BALF PC, the concentration of PC16:0/16:0 was low in ETLF. As expected on the basis of this molecular species composition of PC, ETLF did not generate low surface tension values under dynamic compression in a pulsating bubble surfactometer.We conclude that the surfactant in ET is different from lung surfactant, and that low surface tension is not a major determinant of ETLF function.     

On sieve tube function

Summary Several theories of phloem transport are currently being considered in various laboratories on the basis of recent evidence. Proponents of the activated diffusion or protoplasmic theories claim support in the disclosure of fibrils, longitudinally arranged, in the connecting strands passing across sieve plates, and in the close connection between respiratory activity and transport. Those favoring a surface migration theory claim support in the demonstrated systems of sieve element lamellae, along whose surfaces one could imagine solute transport to occur. Proponents of the pressure flow theory point to results of exudation studies, tracer investigations, and to histochemical evidence indicating that sieve elements are relatively inactive, metabolically, as well as to the suggestion that perhaps the connecting strands are more open (tubular) than they have been considered to be up to now.Callose formation is stimulated by turgor changes, promoted by foreign chemicals, viruses, and, in the sieve element, by a relatively alkaline pH, a high sucrose concentration, and doubtless by the unique unbalanced character of sieve sap composition. The function of callose in older or wounded elements appears to be a constricting or plugging action, but its function in young mature elements is essentially obscure.Recent evidence augments the view that sieve elements display an extraordinary sensitivity towards experimental manipulation.     

Conductive hearing loss caused by eustachian tube dysfunction according to the data of functional computed tomography

The paper deals with computed tomography (CT) diagnosis of Eustachian tube dysfunction. A functional multislice spiral (MS) CT protocol has been first elaborated for the Eustachian tube. Twenty-three patients with unilateral conductive hearing loss and Eustachian tube dysfunction were examined. The normal functional anatomy of the Eustachian tube was evaluated on the side without evidence of pathology in 23 patients. Functional MSCT showed that the cartilaginous portion of the Eustachian tube opened partially and closed completely in 9 patients. Ten patients were found to have steady changes in the cartilaginous portion of the Eustachian tube. The developed method could confirm the cause of conductive hearing loss and optimally define a treatment policy.