The Longitudinal Fibromuscular Component of the Soft in the Fifteen-Week Human Fetus:

Musculus Uvulae and Palatine Raphe

HERBERT L. LANGDON, Ph.D. KATHLEEN KLUEBER, M.S. Pittsburgh, Pennsylvania 15261

The structural relationships of the longitudinal fibromuscular component of the (musculus uvulae and raphe) were studied using histologic sections from 19 early human fetal specimens. Musculus uvulae arises in association with the palatine aponeurosis near the beginning of the second quadrant of the velum, follows a sigmoid course, and terminates near the base of the uvula. In addition, an occasional muscular loop may arise from the bony palate, arch downwards, and then recur into the uvular muscle. A complex relationship exists between the raphe in the velum and several palatal muscles. With regard to musculus uvulae, small muscular bundles arise from the raphe to embrace the muscle near its crest. These branches may aid in contouring the dorsal surface of the velum in the region of the levator eminence to complement the surface of the posterior pharyngeal wall and thus enhance the efficiency of the velopharyngeal seal.

Introduction received considerable attention in the litera- ture from the perspectives of comparative In the early human fetus, as well as in the (Kuenzel et al., 1966), prenatal de- adult, musculus uvulae and the palatine velopment (Doménech-Ratto, 1977; Peter, raphe form a longitudinally-oriented fibro- 1913; Futamura, 1906), and the gross anat- muscular complex running the length of the omy of the muscle in the adult (Azzam and soft palate. The uvular muscle overrides the Kuehn, 1977; Kriens, 1975; Voth, 1961; Rue- other palatal musculature in the dorsal mid- dinger, 1879; Henle, 1873). Nevertheless, line of the velum, while the raphe, situated areas of disagreement and uncertainty con- ventrally, runs a parallel course immediately tinue to exist concerning aspects of this mus- deep to the . cle's structure and relationships within the _- The 15-week fetus was selected for this velum. study on the morphology of the velopharyn- The palatine raphe is a landmark easily geal musculature primarily because it serves visualized from the ventral surface of both the as a model of convenient size for examining hard and soft . The anterior half of the the structure of this mechanism at the micro- raphe, related to the , has been scopic level. While fetal anatomy differs con- examined extensively because of its associa- siderably from adult structure in size and, to tion with the epithelial pearls found there a much lesser extent, in spatial relationships, during fetal and neonatal life (Burdi and if used judiciously, this model nevertheless Faist, 1967; Wood and Krause, 1962; Peter, provides an excellent means for surveying 1924; Bergengruen, 1909). However, since basic velopharyngeal fibromuscular arrange- pearls have not been observed to form within ment. : the soft palate to any extent, the relationships The morphology of musculus uvulae has and attachments of the raphe in the velum This research has been supported in part by the U. S. have tended to be overlooked. __ Public Health Service Grant DE-1697, National Institute Jonnesco (1912), describes the raphe as at- of Dental Research, and Health Research and Services taching anteriorly in the region of the palatine Foundation Grant 0-85. papilla and then passing caudally in midline The authors are affiliated with The Cleft Palate Cen- ter and Department of Anatomy (Dental Medicine), to become continuous with a corresponding University of Pittsburgh, Pittsburgh, PA 15261. structure in the soft palate. In addition, the 337 338 Cleft Palate Journal, October 1978, Vol. 15 No. 4 The objective of the present study is to Legend for Identification of Figures describe the morphologies of musculus uvulae MU M. uvulae and the palatine raphe, emphasizing their A Arches of raphe structural inter-relationships, which, in turn, R Axis of raphe suggest possible functional implications in the TM Transverse musculature mechanism of velopharyngeal closure. PA Palatine aponeurosis BP Bony palate Materials and Methods RM Recurrent muscle Gestational ages of the 19 human fetuses (lateral) used were determined according to estab- B Branches of raphe lished criteria (Streeter, 1920) to be 15 t 2 T Termination of raphe weeks. All specimens appeared typical-for-age MT M. tensor veli palatini as determined by gross inspection. Following PNS Posterior nasal spine routine histologic processing, ten of the heads G Glandular tissue and ducts were sectioned (30 micra) in the coronal plane TG while the remainder were sectioned sagittally. | C.T. Inclusion All even-numbered sections were stained ac- H Hamulus cording to a modified Masson trichrome tech- nique. raphe has been reported to take supplemental Pilot work suggested the use of tracings attachment to the posterior nasal spine (Jon- made from every fourth section for the com- nesco, 1912; Henle, 1886), although Luschka prehensive analysis of musculus uvulae and (1868) describes it more precisely as being the raphe, although intervening sections were continuous with the median palatine suture. included when warranted. Following a de- Fibers of musculi levator veli palatini tailed light microscopic examination of each (Todd and Fowler, 1927-28; Ruedinger, stained section of a specimen, tracings were 1879) and palatopharyngeus (Fara and Dvor made at optical enlargements of either 25 % ak, 1970; Jonnesco, 1912) have been observed (sagittal series) or 100 X (coronal series). to attach to the raphe, although this relation- Results ship has been questioned (Podvenic, 1952). In addition, an intrinsic muscular component In mid-sagittal plane, fibers of musculus (musculus uvulae inferior or minor) has been uvulae appear most anteriorly in the velum observed within the anterior one third of the near the beginning of its second quadrant velar raphe where it is described as being with the muscle characteristically having a sharply outline in its perimeter and as existing sigmoid profile or course when viewed lat- separately and distinctly from musculus uvu- erally (Figure 1a). It passes first over and then lae (proper) (Ruedinger, 1879). However, nei- downward and around the posterior bound- ther the number of specimens examined nor ary of the large muscular mass comprised of the frequency with which this muscle arrange- musculi palatopharyngeus, palatoglossus, and ment :was found to occur was reported by levator veli palatini. Upon reaching the lower Ruedinger. Finally, as the raphe approaches half of the palate, the uvular muscle joins its termination, near the base of the uvula, it with fibers of the palatine raphe before resum- is said to become deflected to the left of center ing a posterior course toward the base of the (Piersol, 1911). However, Piersol does not uvula. In this plane of section, the muscle comment further on the nature of its posterior appears to be spindle-shaped, expanding into attachment. a belly near the crest of its slope. The course The raphe itself has been described as a of the individual muscle fibers generally fol- "sharp white line," appearing shortly after lows the axis of the muscle except at its junc- fusion of the palatal shelves in the fetus (Peter, - tion with the raphe, where fiber orientation 1913). Although the term "raphe" suggests may become quite irregular. The sites of ori- this structure to be a product of shelf-fusion, gin of musculus uvulae vary considerably no description of actual raphe-formation has among the specimens examined, and their been found. ‘ attachments may be visualized as arising from Langdon and Klueber, ronctruomat rimromuscurar component mn verum 339

FIGURE la. Sagittal section through velum illustrating the course and relationships of M. uvulae (32 % , specimen 3-1546, section 516).

FIGURE 1b. Schematic diagram of the sagittal section shown in Figure la, demonstrating the points at which coronal sections illustrated in Figures 4 through 11 were taken.

340 Cleft Palate Journal, October 1978, Vol. 15 No. 4 positions anterior, superior, and/or inferior to showed no obvious connection with the raphe. the muscle per se. When present, this recurrent muscle contrib- The principal anterior attachment of the utes significantly to the bulk of musculus muscle is to the posterior edge of the bony uvulae. A second group of inferiorly-related palate via an intermediate zone of fibrous fibers is observed to traverse, singly or in small connective tissue. This origin may be well bundles, the boundary between the uvulae defined as consisting of one or more tendons, muscle. and the underlying musculature (Fig- or it may be diffuse, losing its identity within ures 5 and 6). the substance of the palatine aponeurosis. In In Figure 3, musculus uvulae is depicted in two specimens (n = 10) a limited number of a coronal section through the velum at the muscle fibers originated anteriorly in the level of the pterygoid hamuli. Subsequent transverse plane, sharing this orientation with illustrations (Figures 4 through 11) character- most of the connective tissue fibers of the ize changes in the morphology of musculus aponeurosis as well as with those fibers of uvulae at points along its posterior course in musculus palatopharyngeus attaching in this the velum (see Figure 1b). part of the velum. Subsequently, these fibers In cross-section, the anterior part of the bend through a 90-degree are to join with uvular muscle typically has a lentiform shape those of the uvular muscle. and a predominantly longitudinal fiber ori- Superiorly, some fibers in all specimens entation (Figure 4). Although the muscle is were found to arise from the inferior surface bounded dorsally by fascia throughout its of the overlying aponeurosis. In 33 percent of course in the velum, it is overlapped by the the specimens, a fiber origin is seen inferiorly palatine aponeurosis only slightly at its ante- as a muscular component having a variable rior end. The posterior-most extent of the relationship to the raphe. This attachment aponeurosis is seen as the dense investment may be characterized as originating from the located immediately above the muscle in Fig- posterior edge of the bony palate and as tak- ure 4. Musculus uvulae generally overrides ing a "U"-shaped course, running first infe- the large transversely-oriented muscle mass at riorly toward the raphe and then recurring midline until it begins its downward course in into musculus uvulae (Figure 2). The depth the posterior one-third of the velum. of the "U" differed markedly among the spec- More posteriorly (Figure 5), obliquely-ori- imens having this muscular component, rang- ented muscle fibers entering musculus uvulae ing from a deep bend touching the raphe on its ventral surface tend to separate the inferiorly to a more horizontal structure which longitudinal component of this muscle into

FIGURE 2. Parasagittal section through velum illustrating the course of the recurrent muscle from the bony palate into M. uvulae (70 % , specimen 3-1546, section 502).

Langdon and Klueber, ronerrupmar rreRomuscuLar comPonENT N vEruy 341

bilateral "bundles." While differing in extent (Table 1), this bundled appearance has been encountered frequently (in 90 per cent of the ten coronally-sectioned specimens) in the cen- tral one-third of the velum. Likewise, muscle fibers joining the uvular muscle from below are also shown in Figure 6. Perhaps more striking here, however, is the presence of a midline connective tissue inclusion partially separating the bundles on either side. Inclu- sions similar to this were seen occasionally in all of the coronally-sectioned specimens. The belly of musculus uvulae, when visu- &A alized in sagittal profile (Figure 1), occurs FIGURE 3. Coronal section through the anterior where the muscle crests over the posterior velum. Brackets outline the area occupied by M. uvulae, as shown in greater detail in Figure 4 (15X, specimen 3- surface of the underlying musculature. In 1004, section 464). TABLE 1. Organization of fibers of M. uvulae (bifid or non-bifid) within the anterior, central and posterior thirds of the velum

Plane of Section: Coronal n = 10

1. Nature of M. uvulae within the anterior one-third of the velum a) single 7 b) bifid 2. Nature of M. uvulae within the central one third of the velum a) slightly "bundled"

co b) moderately to prominently "bundled"

o c) bifid

O d) unknown *

- FIGURE 4. Section 464 located at 5 percent of the 3. Nature of M. uvulae within the posterior muscle's length. Note: Figures 4 through 11 are enlarged one-third of velum coronal sections through M. uvulae at points along its a) single course which demonstrate significant anatomic relation- b) bifid 2 ships (120 X , specimen 3-1004). * Incomplete specimen

s w- FIGURE 5. Section 484 located at 31 percent of the _ : a m see wa marae " muscle's length. Arrows indicate the obliquely-running FIGURE 6. Section 492 located at 42 percent of the fibers entering the ventral aspect of the muscle. muscle's length.

342 Cleft Palate Journal, October 1978, Vol. 15 No. 4 cross section at this point, the muscle is large for example, the plane of section is passing and nearly round (Figure 7). Note that several through the posterior-most tips of a bifid-end- of its fibers have already assumed an oblique ing muscle, although the uvula in this speci- orientation. A condensation comprised of men remains single. Connective tissue stroma musculus palatopharyngeus and connective tissue can be seen arching transversely over the uvular muscle, along with a few fibers of musculus palatoglossus approaching it on its lateral aspect. In all specimens in this or a slightly more posterior region, muscle fi- bers from the raphe and its branches can be seen ascending nearly perpendicularly both through and around musculus uvulae, often forming a "V" configuration such as the one seen in Figure 8. In Figure 9, musculus uvulae is shown midway in its descent. Its bulk ap- pears to be concentrated into two lateral bun- dles separated by obvious intermediate or interconnecting muscle fibers. Upon reaching the bottom of its slope, musculus uvulae resumes a posterior course towards the uvula. In so doing, it exhibits three features common to all specimens at this point (Figure 10): the cross-sectional diameter diminishes as the muscle tapers posteriorly; its fiber pattern (primarily linear in orienta- tion) becomes less regular at its intersection with the raphe; and the ducts of palatine FIGURE 8. glands can be seen weaving among the muscle muscle's length. fibers. In the same region, a few fibers of the palatopharyngeal muscle frequently form an arch over musculus uvulae. The nature of termination of musculus uvulae, i.e., whether single or bifid (occurring with a frequency of 80 and 20 per cent respectively in the ten coronally-sectioned specimens), appears to be independent of uvular shape. In Figure 11,

p Si usu en FIGURE 7. Section 504 located at 57 percent of the muscle's length. Arrows indicate the palatoglessal fibers FIGURE 9. Section 320 located at 78 percent of the entering the muscle laterally. muscles length.

Langdon and Klueber, LonctTupmNat FBROMUSCULAR COMPONENT IN vELUM 343 and gland ducts can be seen here radiating straight course, at least following histologic outwards towards the surface. processing, is evident also in Figure 12. The palatine raphe was present in the In summarizing the nature of the anterior velum in each of the specimens surveyed in relationships of the velar raphe (Table 2), the present study, although returning, for ex- teac ample, to Figure 1a, only isolated segments of the raphe may be seen in the median plane. If adjacent sections are superimposed upon one another, however, the continuity of these segments becomes readily apparent. That the raphe frequently does not appear to have a

FIGURE 12. Transverse section through the anterior velum demonstrating a supplementary attachment of the raphe to the hard palate in the region of the PNS. Arrows indicate palatopharyngeal fibers attaching to the raphe. (60 x , specimen 3-297, section 470).

TABLE 2. Anterior attachments and muscular relationships of the palatine raphe in the velum

FIGURE 10. Section 524 located at 84 percent of the 1. Anterior attachment(s) of the pala- muscle's length. Arrows indicate palatopharyngeal fibers tine raphe in the velum (in sagittal arching over M. uvulae. specimens, n = 9) a) to the bony palate in the region 67 per cent of the posterior nasal spine b) continuity with the raphe pres- ent in the hard palate (1) as a sub-epithelial density 33 per cent (2) as a free bundle 67 per cent 2. Muscular relationships of the pala- tine raphe in the velum a) recurrent muscle (in sagittal specimens, n = 9) (1) single 22 per cent (2) bifid 11 per cent b) muscle fibers appearing within the raphe (sagittal + coronal specimens, n = 19) (1) present in anterior A 37 per cent (2) present in middle % 10 per cent FIGURE 11. Section 520 (of specimen 3-1503) lo- (3) present in posterior !4 5 per cent cated at 99 percent of the muscle's length. 344 Cleft Palate Journal, October 1978, Vol. 15 No. 4 - sagittally-sectioned specimens readily show In addition to its axis, the raphe character- that, in all cases, the raphe is a continuous istically also includes two major (principally entity, running the length of the entire palate. muscular) branches. These follow an oblique Usually (in 67 percent of the nine sagittally- (postero-superior) course to embrace muscu- sectioned specimens), it exists as a free bundle lus uvulae bilaterally in the region of the in the hard palate, although it was fused to muscle's crest (Figure 14). In the coronal as- the submucosa in the remainder of the sam- pect (Figure 8), these branches are seen to rise ple. Epithelial pearls generally accompany divergently from the ventral midline, in the the raphe through the hard palate, but dis- manner of a "V," to end alongside musculus appear as the raphe continues into the velum. uvulae. A few fibers may actually arch over A supplemental attachment of the raphe to the muscle at this point. the posterior median aspect of the palatine In addition to the muscle tissue already bones was frequently noted (67 percent, n = described as being associated with the termi- 9). nations of the arches and with the lateral More caudally in the velum, characteristi- branches of the raphe, an additional muscular cally in its posterior one-half, connective tissue component may be found running within the arches may be seen arising from the upper axial raphe in some specimens (Table 2). In surface of the raphe to terminate within mus- these instances, the fibers traced serially culus uvulae. These arches, present in all spec- within the coronal series proved to be the imens, vary in number and density from one central extensions from musculi levator veli specimen to another (cf. Figures 1 and 13). palatini and palatopharyngeus, which run They tend to be relatively straight in mid- within the raphe for a distance before termi- velum and to become increasingly arched nating there (Figure 12). (concave anteriorly) more caudally. Occasion- In summary, the velar raphe is continuous ally, the upper extent of an otherwise collag- anteriorly with its counterpart in the hard enous arch becomes muscular in nature as it palate and frequently attaches to the bony nears the inferior aspect of the uvular muscle. palate as well. Collagenous arches arise at The raphe terminates in the velar midline intervals along its course to intersect with by intersecting with musculus uvulae as that musculus uvulae. Posteriorly, the raphe and muscle approaches the uvula (Figure 1). Al- muscle join near the base of the uvula. Also though a few fibers of the raphe may join in this region, two fibromuscular branches with those of the muscle and travel with it for leave the raphe to approach the uvular muscle a distance, most appear to pass more or less bilaterally. Of the two remaining muscle com- perpendicularly through the muscle, and of- plexes associated with the raphe, one is com- ten project slightly on its dorsal surface. prised of central ends of transverse muscle

~ kee =- _

Ain ar FIGURE 13. Sagittal section through the velum il- FIGURE 14. Parasagittal section through the poste- lateral branch lustrating a number of fibrous arches arising from the rior velum illustrating fibers (arrows) of the uvulae near its raphe and running upwards into the substance of M. (left) of the raphe running alongside M. uvulae (75 X, specimen 3-235, section 478). crest (90 % , specimen 3-1546, section 324).

Langdon and Klueber, LONGITUDINAL FIBROMUSCULAR COMPONENT IN VELUM 345

FIGURE 15. Schematic diagram illustrating the interrelationship of M. uvulae with components of the raphe. fibers running axially within the raphe. The found in the literature. This arrangement may other is an occasional adjunct to musculus represent a phylogenetic remnant of a pala- uvulae. ‘ topharyngeal contribution to musculus uvu- lae, the anterior attachment of which remains Discussion intact. ~ ' The anatomy of musculus uvulae described Others have maintained that the uvular in the present fetal study corresponds closely muscle in the adult is enclosed within a com- on many points with the observations of Rue- partment formed either by the splitting of the dinger in his classic monograph (1879) on the palatine aponeurosis (Whillis, 1930) or by a musculature of the adult velum. Both the fibromuscular (elastic fiber and smooth mus- relevance of his work and its priority suggest cle) ensheathment (Voth, 1961). In the pres- it as a basis for comparison as the results of ent study the entire palatine aponeurosis was the current study are being discussed. observed to pass dorsal to musculus uvulae.: Although a fleshy origin for the uvular Since elastic fibers form around the 16th week muscle from the palatine bones has not been of development (Wood and Kraus, 1962), any observed in this study, the occasional presence contribution they may ultimately make in the of a direct tendinous attachment of it to the structure of the palate cannot be analyzed as hard palate may account for descriptions (e.g., part of the present study. Fara and Dvorak, 1970) which cite the muscle In the 55 mm. human fetus, Doménech- as attaching directly to bone. Instead, the Ratto (1977) describes musculus uvulae as present investigation confirms that a majority lying dorsal, rather than ventral, to the pala- of anterior fibers of musculus uvulae originate tine aponeurosis. The photograph with which from the palatine aponeurosis. Reference to he illustrates this relationship (Figure 13, occasional fibers of the uvular muscle taking Doménech-Ratto, 1977) suggests that what he attachment in line with transversely-oriented is referring to as the palatine aponeurosis is aponeurotic fibers, however, has not been more likely musculus levator veli palatini. In 346 _ Cleft Palate Journal, October 1978, Vol. 15 No. 4 the experience of the present investigators, the that a continuous connective tissue septum or fetal palatine aponeurosis does not extend a non-muscular space intervening between a appreciably beyond the anterior one-third of muscular component on either side is lacking. the velum, whereas the section in question Thus, although the possibility of eventual appears to be taken from the region of the bilaterality may be implied from the muscle's . crest of the uvular muscle. early pattern of development, a survey of the The present data confirm the descriptions specimens employed in the present study sug- by Voth (1961) and Ruedinger (1879) of mus- gests that, by this stage of development, it culus uvulae being bounded inferiorly and rarely, if ever, persists. laterally by other palatal musculature (Fig- When midline connective tissue inclusions ures 4 and 7). These investigators also re- were observed in the uvular muscle (e.g., Fig- ported the existence of fibers passing trans- ure 6), they were isolated occurrences and versely over the uvular muscle in the posterior were not found in consecutive sections. Voth one-third of the velum. A component of mus- (1961) noted the presence of collagenous sep- culus palatopharyngeus was observed to arch tation to be inconsistent but, nevertheless, a over musculus uvulae in this region in several frequent occurrence in adult palates. The cur- specimens examined in the current study. rent study suggests that the isolated points of Both in the adult (Ruedinger, 1879) and in "septation" are the upper extents of the fi- the present fetal study, musculus uvulae ex- brous arches from the raphe. panded from a flattened to a rounded profile In the present study, the location of the as seen in coronal section (Figures 4 through belly of musculus uvulae supports Dickson's 7), while being devoid in its middle one-third (1975) assertion that the muscle's greatest ver- of either palatine aponeurosis or overlying tical dimension is within its third quadrant. musculature (Figures 5 through 7). Azzam and Kuehn (1977) and Dickson (1975) A long-standing controversy spanning the suggest that the muscle at this point may last century questions whether the uvular influence to some extent both the bulk and muscle is a single midline- or paired bilateral- shape of the levator eminence. muscle mass. Ruedinger (1879) observed that, Although glandular tissue is interspersed upon removal of the mucous membrane from throughout the velum, it is found increasingly the dorsum of the adult velum, musculus around the course of musculus uvulae in its uvulae appeared to consist of two lengthy posterior one-third (Figs. 1 and 10). This ob- muscle bundles. However, sectioning this tis- servation is in accord with the suggestion of sue in the coronal plane revealed that these Ruedinger (1879) and Fara and Dvorak "two columns" actually constituted a single (1970) that such a relationship might facili- muscle mass. By contrast, gross and micro- tate glandular secretion. The density of the scopic examinations of adult palates by Az- glandular tissue and the extent to which its zam and Kuehn (1977) showed a continuous presence may divert the course of fiber bun- septum separating musculus uvulae into two dles of the uvular muscle appears to be con- separate muscles. In this regard, it may be siderably greater in the adult (Ruedinger, helpful to recall that the uvular muscle de- 1879) than was observed in the present study. velops as a pair of columns which arise sepa- Variable types of ending for the uvular rately and, in time, merge at midline (Futa- muscle have been observed in this study; such mura, 1906). Doménech-Ratto (1977) reports have also been described in other reports. For that, while the fetal musculus uvulae is paired example, Azzam and Kuehn (1977) and Rue- in specimens under 50 mm (about 45 days), dinger (1879) state that musculus uvulae be- the bilateral bundles coalesce at later stages comes bifid as it approaches the uvula. This into a single midline structure. The degree to phenomenon is occasionally seen in the fetus which the fusion process goes to completion (Table 1). Musculus uvulae has also been appears to be somewhat variable, as by the described by Henle (1873) as ending as a - third intrauterine month (in the present single tapering bundle or in a brushlike fash- study) bifidity of the anterior and/or posterior ion, both conditions frequently seen in the end(s) is frequently encountered (Table 1). present study. While Azzam and Kuehn However, histologic examination indicates (1977) as well as Ruedinger (1879) report Langdon and Klueber, LONGITUDINAL FIBROMUSCULAR COMPONENT IN VELUM 347 occasional fibers from the uvular muscle at- be observing slightly different stages of devel- taching directly to the basement membrane opment, although the specimens used are clus- of the uvula, fleshy attachment of this muscle tered around a 15-week time period. The to the membrane was not seen in the present characteristic curvature of the arches in the study. However, a connective tissue continu- posterior one-third of the velum corresponds ity between these two structures is clearly to the area occupied by the "sling" formed by suggested in Figure 11. musculus palatopharyngeus. Although it has The present study confirms in the fetus been suggested (Gisel, 1962; Voth, 1961) that several of the standard descriptions of the musculus uvulae has no antagonist within the anterior relationships of the velar raphe found velum, the combined vectors of musculi le- in the literature for the adult. These similari- vator veli palatini and palatopharyngeus ap- ties include continuity with its anterior coun- pear appropriately situated to carry out this terpart, supplemental attachment to the bony function (Braithwaite and Maurice, 1963; palate, and lack of association with epithelial Podvenic, 1952). The placement and shape of pearls (Burdi and Faist, 1967; Wood and the posterior arches, especially, imply that Kraus, 1962; Kitamura, 1966; Peter, 1913; they may play a role as pulleys around which Jonnesco, 1912; Luschka, 1868). In addition, the more posteriorly located palatopharyn- observations in the present study correspond geal fibers pass. The straighter arches more with those of Fara and Dvorak (1970), Todd anteriorly situated appear to tie together the and Fowler (1927-28), Jonnesco (1912), and two longitudinal components of the velum, Ruedinger (1879) that some fibers of musculi thus limiting the extent of palatal distortion levator veli palatini and palatopharyngeus otherwise probable upon contraction of the may insert into the raphe. transversely oriented musculature. Such con- However, it is not easy to reconcile any of traction may contribute to the sigmoid shape the muscular relationships described above typifying the uvular muscle as seen in longi- with Ruedinger's (1879) observations con- tudinal section (Ruedinger, 1879). cerning musculus uvulae minor in the adult, Finally, contraction of the lateral branches vis., its appearing within the connective tissue may have the effect of pulling downward on raphe and remaining separate from musculus the tissue on either side of musculus uvulae in uvulae. Presumably, Ruedinger did not trace the region of its crest, thereby raising the the muscle to its attachment at either end, muscle's contour on the dorsal midline of the which suggests the possibility that he may velum. It appears likely, therefore, that factors actually have been observing the anterior other than just contraction of the levator mus- ends of the levator or palatopharyngeal mus- cle contribute to the functional shaping of the culature running within the raphe for a dis- dorsal palatal surface, especially at midline. tance before terminating there. The nature of References the recurrent muscle (its attachment to mus- AzZzAM, N. A., and D. P., The morphology of the culus uvulae and its frequent discontinuity musculus uvulae, Cleft Palate J., 14, 79-87, 1977. with the raphe) makes it an unlikely candi- BrErcENGRUEN, P., Epithelperlen and epithelstraenge in date for Ruedinger's musculus uvulae minor. der Raphe des harten Gaumens, Arch. Entw. Organ. 28, Although the possibility cannot be excluded 277-326, 1909. BrAITHwWAITE, F., and Maurice, D., The importance of that the difference between Ruedinger's ob- the levator palati muscle in cleft palate closure, Brit. J. servations and those of the present study on Plast. Surg., 21, 60-62, 1968. this point may simply relate to differences Burp1, A. R., and Faist, K., Morphogenesis of the palate between the adult and prenatal samples em- with special emphasis on the mechanisms involved, Am. J. Anat., 120, 149-160, 1967. ployed, the probability of such seems remote. Dickson, D. R., Anatomy of the normal velopharyngeal The current study demonstrates the pres- mechanism, Clin. Plast. Surg., 2, 235-248, 1975. ence of intermediate relationships of the raphe DomgnrEcH-RatTro, G., Development and peripheral in- with other parts of the velum not heretofore nervation of the palatal muscles, Acta Anat., 97, 4-41, mentioned in the literature, vis., the arches 1977. FAra, M., and DvorAx, J., Abnormal anatomy of the and lateral branches. The apparent variation muscles of palatopharyngeal closure in cleft palates, in density of the arches from specimen to Plast. Reconstr. Surg., 46, 488-497, 1970. specimen suggests the possibility that one may FUTAMURA, R., Ueber die Entwickelung der Facialismu- 348 Cleft Palate Journal, October 1978, Vol. 15 No. 4

skulatur des Menschen, Anat. Hefte, 30, 434-516, 1906. PrEtER, K., Atlas der Entwicklung der Nase and des Gaumens GiseEr, A., Zur funktionellen Anatomie des Schluckaktes, beim Menschen, Gustav Fischer Verlag, Jena, pp. 32-34, Anat. Anz., 111, 321-322, 1962. 1913. Grar, P., Eigenartige Strukturverhaeltnisse in der PETER, K., Die Entwicklung des Sacugetiergaumens, - Muskulatur des menschlichen Uvula, Zeitschr. Anat. Zeitsch. f. d. Ges. Anat., 25, 449-564, 1924. Entw., 114, 399-419, 1949. Pirrsor, G. A., Human Anatomy, J. B. Lippincott, Phila- Hens, J., Gaumenmuskeln, in Handbuch der systematischen delphia, pp. 1568-9, 1911. Anatomie des Menschen, Vol. 1, Braunschweig, Druck Popvinr®c, S., The physiology and pathology of the soft und Verlag von Friedrich Vieweg und Sohn, pp. palate, /. Laryngol. Otol., 66, 452-461, 1952. 120-124, 1873. Rurpmngr®, Beitraege zur Morphologie des Gaumensegels und Jonnesco, T., Tube digestif, in Poirier, P., and Charpy, des Verdauungsapparates, J. G. Cotta®schen, Stuttgart, pp. A., (ed.), Traite D' Anatomie Humaine, Vol. 4, Part 1, 11-15, 1879. ‘ Masson et Cie, Paris, pp. 50-102, 1901. STREETER, G. L., Weight, sitting height, head size, foot Krramura, H., Epithelial remnants and pearls in the length, and menstrual age of the human embryo, Contr. in the human abortus, Cleft Palate ]., to Embryol., II (274), 146-160, 1920. ’ 3, 240-257, 1966. Topp, T. W., and FowLrrrR, R. H., The muscular relations KriEns, O., Anatomy of the velopharyngeal area in cleft of the tonsil, Am. J. Anat., 40, 355-371, 1928. palate, Clin. Plast. Surg., 2, 261-283, 1975. VotH, D., Zur funktionellen Morphologie des men- KuenzeEL, G., Lucknaus, G., and Scnorz, P., Verglei- schlichen Gaumens, Anat. Anz., 110, 165-176, 1961. chend-anatomische Untersuchungen der gaumensegel J., A note on the muscles of the palate and the Muskulatur, Zeitschr. Anat. Entw., 125, 276-293, 1966. superior constrictor, J. Anat., 65, 92-95, 1930. LuscHmKa, H., Der Schlundkopf des Menschen, H. Woon, P. J., and Kraus, B. S., Prenatal development of Laupp'schen Verlag, Tuebingen, pp. 42-51, 1868. the human palate, 4rch. Oral Biol., 7, 137-150, 1962.