Cleft Palate Velopharyngeal Musculature in a Five-Month-Old Infant

Home , Levator veli palatini, Palatine aponeurosis, Palatoglossus muscle, Palatopharyngeus muscle, Pterygoid hamulus, Stylopharyngeus muscle

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, lamina perpendicularis 42. Os hyoideum, cornu majus 18. Os palatinum, lamina horizontalis 43. One of anterior drill holes 19. Tuber maxillae (tuberosity) 44. Posterior drill hole 20. Uvula (hemi) 45. Superior drill hole 21. Lingua 46. Medial drill hole 22. Concha nasalis 47. Lateral drill hole

FIGURE 1. Medial view of oronasopharyngeal specimen re- moved from right side for histological study showing, from above down, cranial base, lateral nasopharyngeal wall, cleft palate, and tongue.

quate visibility. It was necessary to divide horizontal reconstruction was split into six both reconstructions into a number of parts parts on anatomical levels and the coronal of about 20 sheets each in which visibility was reconstruction into eleven levels. The levels good, individual structures isolated, and con- photographed quite well to provide a record cealment of detail due to superimposition of of the entire reconstructions in detail. The one structure upon another minimal. The artist's drawing involved an element of inter-

4 Cleft Palate Journal, January 1980, Vol. 17 No. 1 pretation and repeated separation of the hor- the posterolateral pharyngeal region. These izontal reconstruction into levels for clarifi- included the levator veli palatini, the palato- cation of deeper relationships. Photographs of pharyngeus, the constrictor pharyngis supe- all the levels in both reconstructions are in- rior, and the tensor veli palatini (Figures 2 cluded in the figures to convey both a record and 3). Their identity within and related to of the factual material and to provide a sense the cleft velum could be established by re- of continuity for specific relationships within moving overlying layers of the reconstruction the whole region. so that each muscle could be followed. Smaller muscles readily identified were the Findings hemiuvular, the palatoglossus and the salpin- In viewing the entire horizontal reconstruc- gopharyngeus. tion, four large muscles stood out clearly in Looking at the cleft soft palate itself the

Tensor

SaTpingopharyngetts

Constrictor

Patatophargngeus Nov Ric«ARD (79

FIGURE 2. Drawing of reconstruction of horizontal sections, right side, from an antero-medial and superior viewpoint. Figure 3 gives some indication of how the complete reconstruction actually appeared illuminated from below.

FIGURE 3. Photograph of horizontal reconstruction from approximate viewpoint when drawn by artist for Figure 2. Muscles represented by black ink stand out; bones outlined in red ink do not reproduce well.

Latham et al., cLEFT vELOPHARYNGEAL MUSCULATURE 3 striking feature was the general anterior di- Level H1, Hard Palate and Auditory Tube (Sec- rection in which all the muscle fibers were tions 256-301). Anteriorly, the horizontal oriented. The velar muscle fibers converged process of the palatine bone showed a pro- towards the medial border of the cleft hard nounced posterior nasal hemispine curving a palate and extended within it in medial rela- little laterally. Posteriorly, most of the right tion to the posterior nasal hemispine and auditory tube cartilage (dotted) was seen deep medial border of the palatine bone to just to the torus tubarius and the pharyngeal re- short of the transverse palato-maxillary su- cess (Figure 5). A group of muscle fibers, ture. The anterior muscle, known as the cleft medial to the posterior nasal hemispine, in- muscle of Veau, was seen to consist of a muscle serted both onto the medial edge of the pala- triad including the hemiuvular and parts of tine bone and into fibrous tissue anteriorly the palatopharyngeus and the levator veli close to the edge of the cleft. The muscle fibers palatini muscles. The abnormal anterior pre- inserting onto the palatine bone were mainly ponderance of the soft palate musculature of the palatopharyngeus, while those inserting generally was vividly demonstrated. The into the medial fibrous tissue appeared to be hemiuvular muscle was far anterior to its the hemiuvular. Levator's insertion lay infe- normal position which is in the posterior two rior to these and showed predominantly in thirds of the velum; it accunted for a substan- the next level. tial amount of the cleft muscle of Veau. The outlines of the medial and lateral pterygoid plates were distinct features left of SEction RrconstRucTION or center in Figure RicHut Vrrar RrEcion. 5. The tensor veli palatini originated at the scaphoid fossa between the pter- The horizontal reconstruction was divided ygoid plates. At this level, it lay against and into six parts, each selected to show main took origin from the membranous wall of the structures at successive levels as examined auditory tube. superoinferiorly (Figure 4). Level H2. Anterior Muscle Triad and Origins of

A J - h eny \_] \ \ _- YT -| N \.

OND AN_\/

B SJ

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FIGURE 4. Diagram to show H 7 3R described in text. location of layers of horizontal reconstruction illustrated in Figures 5-10 and

6 Cleft Palate Journal, January 1980, Vol. 17 No. 1

PA lateral to the posterior drill hole. This was close to its origin on the infero-medial border of the auditory tube cartilage. The tensor palati at its widest part was also represented at this level just below the auditory tube where it lay lateral to the levator veli palatini. Level H3. Through Belly of the Levator Veli Palatini Sections (355-415). Almost the entire length of the levator veli palatini was dis- played at this level since it lay mainly in the horizontal plane (Figure 7). From its origin on the temporal bone, it made a shallow curve under the auditory tube and cartilage and then rose slightly. Its muscle fibers began to insert into fibrous strands which, with some muscle fibers, converged toward the medial aspect of the palatine bone. The hemiuvular muscle descended on the medial aspect of levator just a little posterior to the hard palate. The superior division of the lateral part of the palatopharyngeus appeared as some small bundles that ascended around the medial aspect of levator and showed between the two anterior drill holes. The main division of the lateral part of the palatopharyngeus rose FIGURE 5. Right horizontal reconstruction, Level H1. Hard Palate and Auditory Tube. Three drill holes show in posterior region, one at torus tubarius; other two straddle auditory tube cartilage. Sections 256-301.

Levator Veli Palatini and Salpingopharyngeus (Sec- tions 304-353). Three muscles could be distin- guished converging anteriorly, passing medial to the posterior nasal hemispine to constitute the cleft muscle of Veau (Figure 6). The small bundle of muscle fibers next to the cleft border was the hemiuvular. Its muscle fibers were cut in cross-section and appeared as dots. Lat- erally in the triad was the palatopharyngeus; in the center was the levator veli palatini, which could be followed beneath the orifice of the auditory tube to its origin posteriorly. Levator was crossed diagonally by a small superior division of the lateral part of the palatopharyngeus which continued to an insertion in the palatine aponeurosis antero-laterally (Figures 2, 3, and 6). The cross-over occurred inferior to the orifice of the auditory tube, indicated here by the mucosal depres- sion. Immediately posteriorly was the auditory tube cartilage centered between the drill holes and underlying the torus tubarius. The FIGURE 6. Right horizontal reconstruction, Level salpingopharyngeus muscle was distinctly H2. Anterior muscle triad and levator, salpingopharyn- seen on the medial border of the levator, just geus origins. Sections 304-352. Latham et al., CLEFT VELOPHARYNGEAL MUSCULATURE 7 » (Sections 418-477). From the posterior pharyngeal wall, the superior pharyngeal constrictor turned in a right angle to course anteriorly and to insert on the medial aspect of the pterygoid hamulus. Most of the muscle fibers that lay medial to it belonged to the palatopharyngeus, which was between the three drill holes and the tongue at this level (Figure 8). The muscle on the medial velar border next to the tongue was uvular muscle. The palatopharyngeus lay directly over the tonsil and divided into lateral and medial parts. The lateral part passed antero-superiorly close to the superior constrictor toward the hard palate and palatal aponeurosis. The medial part passed forward in the velum and inserted into fibrous strands which were attached to the medial velar border. The tensor veli palatini hooked around the lateral aspect of the pterygoid hamulus and the superior pharyngeal constrictor attached to the medial hamular aspect. A considerable number of tensor muscle fibers in the pterygoid notch continued in an anterior direction

FIGURE 7. Right horizontal reconstruction, Level H3. Through belly of levator veli palatini. Sections 355- 415.

from beneath levator on its lateral aspect just medial to the medial pterygoid plate and inserted into the whole width of the palatal aponeurosis as well as onto the medial border of the palatine bone (as seen in Level H2, Figure 6). The palatal aponeurosis was best seen in the coronal sections (Figures 13 and 14). The tensor veli palatini muscle at this third level was at its thickest, still lying lateral to the levator (Figure 7). Its tendonous portion grooved the medial pterygoid plate just above the hamulus. The salpingopharyngeus was adapted to the medial aspect of levator and seen just lateral to the posterior registration hole. The stippled structures anterior and posterior to that registration hole were part of the auditory tube cartilage. In the posterior pharyngeal wall the transversely orientated muscle was the superior pharyngeal constrictor. It was joined by an accessory muscle that

originated in common with levator from the FIGURE 8. Right horizontal reconstruction, Level temporal bone. H4. Palatopharyngeus, superior pharyngeal constrictor, Level H4. Palatopharyngeus, Superior Pharyngeal and tensor veli palatini at the hamulus. Sections 418- Constrictor, and Tensor Veli Palatint at the Hamulus 477. 8 Cleft Palate Journal, January 1980, Vol. 17 No. 1 and inserted onto the posterior maxillary tu- muscle rising in the posterior pillar from the berosity, instead of entering the palate around palatoglossus muscle in the anterior faucial the hamulus. pillar (Figure 10). Some fibers from the pala- Level H5. Vertex of Faucial Pillars, Top of toglossus passed anteriorly and joined with Tonsil, and Superior Pharyngeal Constrictor (Sec- the superior constrictor muscle just below the tions 480-522). The anterior registration hole pterygoid hamulus last seen in Level H5 (Fig- passed through the top of the tonsil. The ure 9). The tonsil and faucial pillars were tonsillar bed was bounded laterally by the flanked by the superior pharyngeal constrictor superior pharyngeal constrictor muscle and muscle. posteromedially by the palatopharyngeus muscle (Figure 9). The palatopharyngeus lay Coronat Section ReconstRuction or Lert within the posterior faucial pillar, The dis- Verar REcroxn. crete group of muscle fibers anterior to the The coronal reconstruction was divided tonsil was the palatoglossus muscle lying into eleven levels antero-posteriorly (Figure within the anterior faucial pillar. Constrictor 11). inserted onto both the medial and posterior Level C1. The Hard Palate-Velar Muscle aspects of the pterygoid hamulus. The ante- Overlap (Sections 257-302). A cross-sectional riorly coursing fibers of the tensor veli palatini view of the hard palate with medially related passed between the hamulus and the lateral velar musculature, nasal conchae, and nasal pterygoid plate. The soft palate was closely septum were shown at this level (Figure 12). applied to the surface of the tongue. The hard palate was formed by the horizontal Level H6. Tonsil, Faucial Pillars, and Hemiu- process of the palatine bone. The muscle lying vular Muscle (Sections 522-549). The lobulated at its flattened medial border included fibers tonsil was the distinctive feature at this level of the palatopharyngeus muscle inserting onto and clearly demarcated the palatopharyngeus the bone, of the levator veli palatini muscle,

FIGURE 9. Right horizontal reconstruction, Level FIGURE 10. Right horizontal reconstruction, level H5. Vertex of faucial pillars, top of tonsil and superior H6. Tonsil, faucial pillars and hemiuvula. Sections 525- pharyngeal constrictor muscle. Sections 480-522. 549. Latham et al., cLEFT VELOPHARYNGEAL MUSCULATURE

110 9 8 7 6

N| |-- - ol <-L__| A --* -1+~- ---

| ___

-~ A lp /

Ano / HZ3L _/

FIGURE 11. Diagram to show location of layers of reconstruction in coronal plane illustrated in Figures 12-22.

inferiorly, and of the hemiuvular muscle su- the medial cleft border between the nasal periorly (compare with Figure 6). The upper mucous membrane and the muscle. Glandu- part of the muscle blended into the palatine lar tissue filled the area lateral to the muscle aponeurosis which attached along the upper group and inferior to the aponeurosis. edge of the posterior palatal border. The con- Level C3. Levator Veli Palatin: Dispersed, tours below the three marker holes lateral to Hemiuvular and Tensor Tendon (Sections 353- the palatine bone represented the tuberosity 380). In proceeding posteriorly, the anterior of the maxilla. Muscle fibers of the tensor veli muscle triad dispersed; the hemiuvular mus- palatini were related to its inferior border. cle coursed inferiorly, remaining close to the Level C2. Medial Velar Muscle Triad and Pal- medial velar border (Figure 14). The levator atine Aponeurosis (Sections 304-349). In the me- veli palatini lay under the arch of the aponeu- dial group of muscle fibers, cut here mainly rosis and wove through glandular tissue. No in cross-section, the hemiuvular muscle was distinction could be made here between le- located on the medial border beneath a thick- vator and palatopharyngeus muscle fibers. ened submucosal fibrous layer (Figure 13). Laterally, the tensor tendon had considerable Deep to the uvular muscle and comprising thickness where it lay infero-medial to the most of the inferior part of the muscle group surface of the palatine bone. was the levator veli palatini. The superior Level C4. Hemwuvular, Levator Veli Palatin, and part was the palatopharyngeus muscle lay Palatopharyngeus Rising at the Level of the Pterygord beneath the palatine aponeurosis and inserted Hamulus (Sections 383-413). The hemiuvular into it. The palatine aponeurosis was a thick muscle lay against the inferior half of the fascial structure that emerged from the ten- velar border and was separated by glandular don of the tensor veli palatini and arched into tissue from the medial part of the palatophar- 10 Cleft Palate Journal, January 1980, Vol. 17 No. 1

curtain of palatoglossus muscle fibers descending in the anterior faucial pillar just anterior to the tonsil. Surprisingly, palatoglossus muscle fibers appeared to originate from the levator muscle. Both at this level and the next (Figures 16 and 17), muscle fibers could be seen issuing from the medial border of levator and turning inferiorly in direct continuity with the palatoglossus muscle group. Some of palatoglossus muscle fibers originated laterally from the direction of the pterygoid hamulus and were seen joining, at the level of the upper border of the tonsil, those fibers descending from the palate. The tensor veli palatini muscle was shown taking origin from the scaphoid fossa at the base of the pterygoid plates. Just superior to the auditory tube orifice, the anterior end of the auditory tube cartilage had a fibrous attachment to the sphenoid bone. Level C6. Belly of Levator Beneath the Auditory Tube Orifice (Sections 482-518). The striking feature was the compact belly of the levator veli palatini muscle which lay directly inferior to the auditory tube orifice (Figure 17). Its FIGURE 12. Coronal reconstruction, Level C1. The anatomical relationship to the auditory tube velar muscle-hard palate overlap. Sections 257-302.

yngeus muscle (Figure 15). The levator veli palatini was grouped in the superior part of the velum. The lateral part of the palatopharyngeus was ascending between levator and the pterygoid hamulus to insert on the aponeurosis. The pterygoid hamulus was a clear feature of this level with the tendon and muscular part of the tensor veli palatini passing on its lateral aspect. Level C5. Body of Soft Palate, Orifice of Auditory Tube and Anterior Faucial Pillar (Sections 416- 476). The body of the soft palate was formed by the belly of the levator veli palatini and palatopharyngeus muscles (Figure 16). Leva- tor lay directly inferior to the orifice of the auditory tube and inferior to levator lay most of the lateral part of the palatopharyngeus. About 10% of the fibers of the lateral part of palatopharyngeus crossed on the superior surface of levator medially to laterally (see also H2, Figure 6). The medial part of the velum had a core formed by the medial part of palatopharyngeus and muscle bundles

spreading from levator. The hemiuvular mus- FIGURE 13. Coronal reconstruction, Level C2. Me- cle lay within the glandular medial border of dial velar muscle triad and palatine aponeurosis. Sections the cleft velum. A noticeable feature was the 304-349.

Latham et al., cLEFT vELOPHARYNGEAL MUSCULATURE 11

itself was elongated vertically in cross-section; it was located between a drill hole in the upper part of levator and one superior to the auditory tube cartilage. This was the level of the torus tubarius. The tensor veli palatini muscle arose laterally from sphenoid bone, auditory tube cartilage, and lateral membranous wall of the auditory tube. The mainly fibrous hemiuvula had a core of glands containing hemiuvular muscle fibers (Figure 18). The part of the velum draped over the mouth of the tonsil contained the medial part of the palatopharyngeus muscle. The lateral part of the palatopharyngeus lay directly over the tonsil and beneath the levator. Level CB. Salpingopharyngeus and the Tonsil (Sections 545-596). The distinguishing feature at this level was the salpingopharyngeus muscle which originated from the inferior border of the auditory tube cartilage and descended to mingle with the palatopharyngeus muscle in the lateral wall of the pharynx (Figure 19). The levator and tensor muscles had a compact

oval form. Together with the auditory tube FIGURE 14. Coronal reconstruction, Level C3. Hemivular muscle, dispersed levator veli palatini muscle and tensor tendon. Sections 353-380. was similar to that of the next three levels posteriorly. The tubal cartilage lay superiorly and medially. Levator veli palatini was inferior, and the tensor veli palatini was in direct contact with the lateral membranous wall of the auditory tube. Most of the medial part of the velum was glandular. A diminished hemiuvular muscle lay at the base of the uvula in a central position. The larger muscle group in the velum medial to the tonsil was the medial part of the palatopharyngeus. The lateral part of the palatopharyngeus was directly over the tonsil and superiorly in contact with levator. The tensor veli palatini was straddled by the three drill holes, and the tonsil was flanked by the superior pharyngeal constrictor. Level CZ. Auditory Tube Cartilage Resting on Levator Veli Palatin (Sections 521-541). The most interesting feature was the shoe-shaped cartilage of the auditory tube as seen in cross- section with the sole of the shoe uppermost (Figure 18). It touched the levator muscle FIGURE 15. Coronal reconstruction, Level C4. inferiomedially. Mechanically speaking, ap- Hemivulvar muscle, dispersed levator veli palatini muscle pearance was much like that of a reciprocat- and palatopharyngeus at the level of the pterygoid ha- ing rocker on a cam wheel. The auditory tube mulus. 12 Cleft Palate Journal, January 1980, Vol. 17 No. 1

last level to show tonsil (compare with Figure 21). The superior pharyngeal constrictor showed a thick upper rim that was separated from palatopharyngeus over the tonsil by a thin fibrous tissue. The styloglossus muscle lay lateral to the tonsil and constrictor in adipose tissue. Level CLIO. Pharyngeal Recess and Muscular Wall of Palatopharyngeus and Superior Pharyngeal Constrictor (Sections 653-692). Immediately behind the tonsil, the palatopharyngeus muscle joined the superior pharyngeal constrictor in forming the muscular lateral wall of the nasopharynx just before it turned into the posterior pharyngeal wall (Figure 21). In the histological sections, the auditory tube was seen to be just medial to the foramen ovale in the skull base and the mandibular division of the trigeminal nerve (not shown in Figure 21). Tensor still took origin from the lateral membranous wall of the auditory tube, and levator took origin from a horizontal fibrous layer that extended laterally from the tubal cap- sule. The approach of stylopharyngeus to the muscular pharyngeal wall was seen in the FIGURE 16. Coronal reconstruction, Level C3. Body next level, but at this level, its fiber bundles of soft palate, orifice of auditory tube and anterior faucial pillar. Sections 416-476. cartilage and the salpingopharyngeus muscle, they enclosed the auditory tube on all four sides. The auditory tube lay beneath the sphenoid bone. The tonsil was flanked by the superior pharyngeal constrictor, and palatopharyngeus lay on it superomedially. The styloglossus muscle showed a rounded cross- section against the lateral surface of constrictor on the same level as the inferior border of the tonsil. Medially, the tip of the hemiuvula was included. The main mucosal surface feature was the posterior faucial pillar which contained the medial part of the palatopharyngeus muscle (Figure 19). Level C9. Levator over Superior Contrictor Rim in Nasopharyngeal Wall (Sections 599-650). The auditory tube coursed laterally away from the nasopharynx, and its lateral membranous wall and cartilage still gave origin to the tensor veli palatini muscle (Figure 20). Tensor touched the lateral border of levator which lay directly beneath the auditory tube. The tonsil was wedged between the palatophar- FIGURE 17. Coronal reconstruction, Level C6. Le- yngeus in the posterior faucial pillar and the vator beneath auditory tube in tubal squeeze position, superior pharyngeal constrictor. This was the velum draped over tonsil. Sections 482-518. Latham et al., CLEFT VELOPHARYNGEAL MUSCULATURE 13

serted muscles. The velopharyngeal muscles mainly affected by the cleft condition were those normally decussating in the midline with contralateral muscles from the other side. These include levator, medial palatopharyngeus, the uvular muscle, and the aponeurosis of tensor. The question of which muscles were relatively unaffected by the cleft, not having an obstacle to normal attachment, is also of great interest. Tensor may be argued to fall in this group along with lateral palatopharyngeus, palatoglossus, salpingopharyngeus, and superior constrictor. With the clarity of the Plexiglas reconstruction method, interest was focused on the relationship of the muscles to the auditory tube. The universal tendency for malfunction of the auditory tube in cleft palate patients has not so far been satisfactorily explained. The ob- vious possibility suggested by the present in- vestigation was that levator was in a position to be obstructive to the active opening of the auditory tube during muscle contraction (Fig- ure 17). This possibility will be examined in

a subsequent paper. However, much opinion FIGURE 18. Coronal reconstruction, Level C7. in the normal open- Hemiuvula, velar drape, auditory tube cartilage resting attributes the major role on levator veli palatini. Sections 521-541. coursed medially through constrictor into palatopharyngeus. This gave the impression that some muscle fibers from the stylopharyngeus muscle reached the soft palate via the posterior faucial pillar. Level C11. Posterior Nasopharyngeal Wall and Stylopharyngeus (Sections 695-756). The superior pharyngeal constrictor turned into the posterior pharyngeal wall (Figure 22). Supe- riorly, it was joined by an accessory part with an origin in common with levator from a fibrous layer beneath and lateral to the auditory tube. The stylopharyngeus muscle pen- etrated the muscular wall on its lateral aspect just behind the tonsil and above the greater cornua of hyoid bone shown in circular cross- section at the bottom of Figure 22. Its direction was mainly inferior, but many fibers coursed in an anteromedial direction to join palatopharyngeus. Discussion The abnormal patter of the velar muscles was well illustrated in the present work, which gave fresh support to the case for intravelar FIGURE 19. Coronal reconstruction, Level C8. Sal- tonsil. Sections 545-596. surgical reorientation of the abnormally in- pingopharyngeus and the 14 Cleft Palate Journal, January 1980, Vol. 17 No. 1

terial, this has been documented by Ruding (1964) and Ross (1971). On the basis of the later report, an incidence of 10% might be expected, although the cleft condition may predispose toward such an insertion. A muscle insertion on the maxillary tuberosity would not be affected by the cleft condition; and, depending upon the actual site of origin of these fibers, one may have to look for reasons other than aberration of the tensor muscle for the cleft-related middle ear problems. Tue Vrerar Patn or Paratoctossus. A surprising observation was that, in this infant, the palatoglossus muscle may represent a portion of muscle fibers from the levator muscle. However, noting that another small bundle arose from the pterygoid hamulus rather than from within the velum, furthers the thought that the name given to the muscle may be a misnomer. The uncertainty over the exact velar distribution of palatoglossus in normal material has been mentioned by Dickson (1975). The diffuse and sparse fibers within the anterior faucial pillar as well as the inter- mingling at the velar level with the lateral FIGURE 20. Coronal reconstruction, level C9. Le- vator approaching superior constrictor rim in lateral nasopharyngeal wall. Sections 599-650.

ing of the tube to the tensor muscle (Rich, 1920; Bluestone, 1971). How the cleft condition disturbs tensor function is not clear and its exact role in the etiology of tubal obstruction, if any, remains to be elucidated. Crerr Muscr® or Veav. The deviant path of levator, which inserts into the medial border of the posterior nasal hemispine and the cleft border, is a well documented finding in cleft palate (Veau, 1931; Ruding, 1964; Fara and Dvorak, 1970; Kriens, 1969, 1975; and Dickson, 1972). In fact, three muscles were seen to contribute to the muscle that extends anteriorly to within the cleft of the hard palate. One of these, the uvular muscle, is described here in the cleft condition for the first time. Of all the velar muscles the uvular muscle was the most anteriorly located and shortened anteroposteriorly. The uvular muscle is in a position to have a shortening effect on the free, mobile border of the cleft velum. Tensor VEL PaLatiNt. The insertion of FIGURE 21. Coronal reconstruction, tensor muscle fibers into the tuberosity of the Level C10. Pharyngeal recess and muscular wall of palatopharyn- maxilla has important implication when geus and superior pharyngeal constrictor. Sections 653- found in the cleft condition. In normal ma- 692. Latham et al., CLEFT VELOPHARYNGEAL MUSCULATURE 15

with a cleft of the secondary palate were studied histologically and by means of Plexi- glas reconstructions. The reconstructions, one for each side, the right sectioned horizontally and the left coronally, provided a three-dimensional, transparent view of the velar muscles with minimal disturbance of their original positions. The abnormally anterior position of the velar muscles and their insertion into the medial border of the cleft hard palate was demonstrated. The cleft muscle of Veau was comprised of three distinct muscles, namely the uvular muscle, and parts of the levator and palatopharyngeus muscles. The levator muscle was in a position relative to the auditory tube and cartilage to obstruct normal opening of the auditory tube. On both sides a substantial bundle of muscle fibers from the tensor muscle inserted onto the tuberosity of the maxilla instead of turning medially around the pterygoid hamulus. Most of the palatoglossus muscle appeared to originate in

the velum as a division of muscle fibers from levator, and some took origin from the pterygoid hamulus. These reconstructions reveal of the velar FIGURE 22. Coronal reconstruction, Level C11. the extent of the abnormality Posterior nasopharyngeal wall and stylopharyngeus mus- muscles in cleft palate and should provide cle. Sections 695-756. valuable information for those, particularly surgeons, attempting to restore normal struc- muscle fibers supports palatopharyngeus ture and function in this multihandicapping surgical contention that the Kriens' (1975) condition. A recent muscle is non-dissectable as a whole. Reprints: Dr. R. A. Latham of normal material by Kuehn and As- study Department of Paediatric & Community Dentistry sam (1978) shed no further light on the velar Faculty of Dentistry palato- path. Whillis (1930) stated that the The University of Western Ontario in- glossus muscle normally inserted onto the London, Ontario N6A 5B7 ferior surface of the palatal aponeurosis. The Canada. normality status of our finding must await definitive clarification of palatoglossus more Acknowledgment: Grateful acknowledgment in normal material. is made to Dr. Doris Bradley and Dr. C. There is insufficient information about the Calabrese for their help with this research. cleft velar musculature to show what varia- tions of muscle insertions may occur. How- References ever, enough is known to justify a strong Brursrong, C. D., Eustachian tube obstruction in the 80 emphasis upon surgical correction of the ab- infant with cleft palate, Ann. Otol. Rhinol. Laryngol., normal muscle insertions. The study of the (Suppl. 2), 1-30, 1971. BraiteewaitE, F. and Maurice, D. G., The importance of post-surgical location of the velar muscles the levator palati muscle in cleft palate closure, Brit. J. with reference to the functions of speech and Plast. Surg., 21, 60-62, 1968. of the auditory tube should become of increas- DeuseHte, F. M., DeStEFaNo, G. A., Loncacre, J. J. and ing interest. and HormstranDp, K., Soft palate musculature anatomical study of full-term cleft palate fetuses using microscope, Cleft Palate Bull., 10, Summary stereoscopic dissection 60-61, 1960. The velar musculature and related struc- Dickson, D. R., Normal and cleft palate anatomy, Cleft tures from a fivemonth-old female infant Palate J., g, 280-291, 1972. 16 Cleft Palate Journal, January 1980, Vol. 17 No. 1

Dickson, D. R., Grant, J. C. B., Sicuer, H., DuBrur, E. of the philtrum and the contour of the vermilion L., and ParTtAN, J., Status of research in cleft palate border: a study of the musculature of the upper lip, /. anatomy and physiology, July 1973-Part I, Cleft Palate Anat., 121, 150-160, 1976. J., 11, 471-486, 1974. RicH, A. R., A physiological study of the Eustachian tube Fara, M. and Dvorax, J., Abnormal anatomy of the and its related muscles, Johns Hopkns Hosp. Bull., 352, muscles of palato-pharyngeal closure in cleft palates, 206-214, 1920. Plast. Reconstr. Surg., 46, 488-497, 1970. Ross, M. E., Functional anatomy of tensor palati-its Krirns, O. B., An anatomical approach to veloplasty, relevance in cleft palate surgery, Arch. Otolaryng., 93, 1- Plast. Reconstr. Surg., 43, 20-41, 1969. 8, 1971. . Kriens, O. B., Anatomy of the velopharyngeal area in Rupinc, R., Cleft palate: anatomic and surgical consid- cleft palate, Clinica in Plastic Surg., 2, 261-284, 1975. erations, Plast. Reconstr. Surg., 33, 132-147, 1964. Kurnn, D. P. and Azzam, N. A., Anatomical character- SEIF, S., and DErroN, A. L., Anatomic relationships istics of palatoglossus and the anterior faucial pillar, between the human levator and tensor veli palatini Cleft Palate J., 15, 349-359, 1978. and Eustachian tube, Cleft Palate J., 15, 329-336, 1978. Lancpon, H. L. and KuurBER, K., The longitudinal R. H., The formation of Passavant's bar, /. fibromuscular component of the soft palate in the Laryngol. Otol., 55, 154-165, 1940. fifteen-week human fetus: musculus uvulae and pala- VEavw, V., Division Palatine, Masson et Cie, Paris, 1931. tine raphe, Cleft Palate J., 15, 337-348, 1978. Wurruts, J., A note on the muscles of the palate and the LaTHAM, R. A. and Deaton, T. G., The structural basis superior constrictor, /. Anat., 65, 92-95, 1930.