Cleft Palate Velopharyngeal Musculature In A Five-Month-Old Infant: A Three Dimensional Histological Reconstruction R. A. LATHAM, B.D.S., PH.D. R. E. LONG, JR., D.M.D., M.S. E. A. LATHAM, M.S. London, Ontario, Canada The structure of the velar muscles in a five-month-old infant with a cleft of the secondary palate was studied using the Plexiglas reconstruction method based on serial histological sections. The right side was sectioned horizontally and the left side in the coronal plane. Sections were projected at a magnification of 18, and muscle fibers and bone and mucosal surfaces were drawn on Plexiglas sheets. Each reconstruction was divided into represent- ative levels which were described in detail. The three-dimensional reconstructions vividly demonstrated the anterior insertion of the levator, palatopharyngeus, and uvular muscles, and the abnormal anterior position of the velar muscles generally. The levator muscle appeared to be in a position to obstruct the auditory tube during muscle contraction. The palatoglossus muscle evidently received a substantial contribution of muscle fibers from levator as well as from some fibers originating from the pterygoid hamulus. A bundle of muscle fibers from the tersor muscle did not pass around the pterygoid hamulus but coursed anteriorly to insert on the maxillary tuberosity. The results provided fresh support for the case of intravelar surgical reorientation of the abnormally inserted muscles. Introduction originally by Veau (1931) who derived the The surgical trend toward intravelar velo- procedure for reconstructing the levator sling plasty reflects a growing awareness of the from his studies of the abnormal anterior abnormality of the velar muscles in the cleft insertions of the velar muscles and his descrip- palate condition (Ruding, 1964; Braithwaite tion of what has come to be known as Veau's and Maurice, 1968; Kriens, 1969). Histori- cleft muscle. However, there is less consensus cally, as reviewed by Kriens (1975), the ana- on the role of the velar muscles in normal tomical velar abnormality was first described eustachian tube function than there is in from dissection studies in the nineteenth cen- speech and velopharyngeal competence. As tury. The outstanding case for striving for an pointed out by Dickson et al. (1974), many anatomically normal palate repair was made details of the intricate structure of the soft palate musculature are still not clear. Some uncertainty is attributable to the techniques Dr. Latham is Professor of Paediatric Dentistry, Fac- of gross and surgical dissection from which ulty of Dentistry, Department of Paediatric & Commu- nity Dentistry, The University of Western Ontario, Lon- most of our knowledge has been derived don, Canada. (Townshend, 1940; Ruding, 1964; Braith- Dr. Long is a Research Fellow at Hershey University waite and Maurice, 1968; Kriens, 1969, 1975; Medical Center and Chief of Orthodontics and President Fara and Dvorak, 1970). Increasing use of of the Lancaster Cleft Palate Clinic, Lancaster, Pennsyl- histological methods may be noted over the vania. ' Mrs. Elizabeth Ann Latham isa speech pathologist at past 20 years (Deuschle et al., 1960; Dickson, St. Mary's Hospital, London, Canada. 1972; Langdon and Kleuber, 1978; Kuehm This paper was read at the 34th Annual Meeting of and Azzam, 1978). the American Cleft Palate Association, San Francisco, The value of preparing three-dimensional California, May 12-16, 1976. Supported in part by NLH. reconstructions from serial histological sec- Grant number DFE 02668 from N.LD.R., by N.LH. Grant number RR 05333 from the Division of Research Facili- tions has been demonstrated recently by Seif ties and Resources, and by Grant number D. G. 133 from and Dellon (1978) in a study of the auditory the Medical Research Council of Canada. tube and related muscles. Within the velum 2 Cleft Palate Journal, January 1980, Vol. 17 No. 1 itself a limitation is placed on this method by at 15 microns. The right half was sectioned the interweaving nature of the velar muscles. horizontally, and the left half was sectioned However, by reconstruction in Plexiglas, this in the coronal plane. Alternate sections were problem was to some extent overcome in a mounted on slides and stained using the Mas- study of the musculature related to the phil- son Trichrome method. trum of the upper lip (Latham and Deaton, RrEconstrRuction Every third sec- 1976). A specimen of the velopharyngeal re- tion was projected onto a white table top at gion of a five-month-old infant with cleft a magnification of 18. Plexiglas sheets of an palate was particularly valuable because of its average thickness of 1.6 mm provided a depth age, being close to the normal age for surgical dimension proportional to the size of the two- repair. In a majority of the works cited above, dimensional projected image. either fetal or adult material was used. For a The projected image of each section was detailed study of the velar musculature, it was then overlaid by a rectangular piece of clear decided to use the Plexiglas reconstructive Plexiglas positioned in a standard orientation method based on histological sections rather and traced using colored, felt-tipped pens as than destroy features of the specimen by dis- follows: muscle fibers (black), tendons (blue), section. To a certain extent, the advantages bone (red) and cartilage (blue stippled). The of dissection and histology were combined in course of muscle, tendon, or ligament fibers that an enlarged transparent view of the velo- was portrayed as accurately as possible using pharyngeal musculature represented the mus- pen strokes ranging from stippling (fiber cross- cles both three-dimensionally and in their section) to long lines (longitudinal). While undisturbed relationships. tracing a particular section, adjacent sections The velopharyngeal muscles are described were simultaneously examined microscopi- as seen in the reconstructions of both sides of cally to obtain accuracy. Consecutive sections the cleft specimen at selected progressive to be traced were oriented relative to the levels in the horizontal and coronal planes of registration holes marked on the Plexiglas histological section. from the previously traced section. In this manner, 99 horizontal tracings were Materials and Methods made on 60 X 35 cm. sheets, depicting the The velopharyngeal region of a five-month- right velopharyngeal area from the auditory old female infant with cleft palate was ob- tube superiorly, to the tip of the uvula infe- tained at autopsy. The cleft involved only the riorly. Coronally, 167 tracings were made secondary palate and was complete in the soft onto 50 X 33 cm. Plexiglas sheets, covering palate and incomplete in the hard palate the left velopharyngeal area from transverse (type II of Veau's classification, incomplete). palatal suture anteriorly, to posterior pharyn- Death was caused by asphyxiation resulting geal wall, posteriorly. from neuromuscular impairment. The speci- The three-dimensional reconstruction was men included the right and left velopharyn- then produced by stacking the serial tracings, geal regions and adjacent bony structures. It superimposed on the registration holes, on an was divided in the midsagittal plane in prep- illuminated screen. Using this reconstruction, aration for histological processing (Figure 1). and constant reference to the histological sec- Hmsrorocicar MrtHon. The tissues were tions for finer detail, the musculature of the fixed in 10% formalin, decalcified in 7% velopharyngeal region was studied and de- formic acid, dehydrated and double-embed- scribed, with special attention to paths, inser- ded using a 2% low-viscosity nitrocellulose tion, and relations to adjacent structures. Vis- solution and histological embedding wax (Tis- ibility of structures within the reconstructions sue Prep)." Three small holes were drilled into from vertically above was poor, and this was each specimen at right angles to the plane of related to the number of Plexiglas sheets sectioning for later registration of drawings: that were superimposed. However, looking derived from sections. Each half was then obliquely downwards through the horizontal sectioned serially on a sliding microtome set reconstruction (99 sheets), excellent views were obtained. The complete coronal recon- ' Fisher Scientific Co., New Jersey. struction (167 sheets) was too deep for ade- Latham et al., CLEFT vELOPHARYNGEAL MUSCULATURE 3 KEY TO ANATOMICAL STRUCTURES IN FIGURES M. levator veli palatini 23. Septum nasi Nor- M. palatopharyngeus 24. Os palatinum, processus pyramidalis t M. palatopharyngeus (lateral part) 25. Lamina medialis processus pterygoidei Ja. M. palatopharyngeus (lateral part, superior di- 26. Lamina lateralis processus pterygoidei vision) 27. Fossa scaphoidea 4. M. palatopharyngeus (medial part) 28. Hamulus pterygoideus 5. M. constrictor pharyngis superior 29. Tuba auditiva 6. M. constrictor pharyngis superior (accessory 30. Ostium pharyngeum tubae auditivae part) 31. Cartilago tubae auditiave 7. M. tensor veli palatini 32. M. buccinator 8. Tendo tensor veli palatini 33. Torus tubarius 9. M. uvulae 34. Tonsilla palatina 10. M. palatoglossus 35. Lateral pharyngeal wall 11. M. salpingopharyngeus 36. Arteria maxillaris 12. M. stylopharyngeus 37. Recessus pharyngeus 13. M. styloglossus 38. Arteria phenopalatina 14. Aponeurosis palati 39. Posterior pharyngeal wall 15. Spina nasalis posterior 40. Arteria palatina descendens 16. Sutura palatina transversa 41. Os sphenoidale 17. Os palatinum,