Study Compares Morphology of Musculus Uvulae in Adults With and Without Cleft Palate Repair

Alyssa KirkmanACPA News, Journal

  • Sex and race appear to have no effect on velopharyngeal anatomy
  • Individuals with previous cleft palate repair tend to have shorter, less voluminous musculus uvulae

CHAPEL HILL, N.C. / Sept. 17, 2019 – New insights on the morphology of the musculus uvulae among adults with normal velopharyngeal anatomy, compared to those of individuals with repaired cleft palates, emerged from a recent study. “Morphology of the Musculus Uvulae In Vivo Using MRI and 3D Modeling Among Adults With Normal Anatomy and Preliminary Comparisons to Cleft Palate Anatomy” was published in the September 2019 issue of The Cleft Palate-Craniofacial Journal (CPCJ).

“Previous studies of the musculus uvulae had included histology, dissection, electromyography, and computational modeling based on hypothetical prediction-based scenarios. However, for various reasons, these methods have provided limited understanding of the muscle tissue morphology,” said Jamie L. Perry, lead researcher. “To improve our limited knowledge of the morphology of the musculus uvulae in vivo, we sought to determine the effects of sex and race of adults with normal velopharyngeal anatomy on muscle morphology, an area that was not examined in prior studies. We then compared that analysis to the palatal anomalies of adults with repaired cleft palate.”

Seventy adults, aged 19 to 34 years old, participated in the study. Those participants with normal velopharyngeal anatomy had no history of cleft palate, craniofacial anomalies, syndromes, neurologic disorders, hearing disorder, or speech disorder, and all had a normal oral mechanism examination indicating no oral abnormalities. Participants with repaired cleft palate self-reported no history of syndromes or secondary palate surgeries (e.g., pharyngoplasty) and indicated normal hearing as an adult at the time of their involvement in the study. Researchers used the definitions of racial groups (Asian, black, and white) as outlined by the National Institutes of Health. Within the Asian group, only individuals of Japanese descent were selected to participate since there is a higher incidence of cleft palate, compared with Chinese, Filipinos, and Koreans.

Within the normal anatomy group there were 33 males and 37 females, and the race distribution consisted of 24 white, 20 black, and 26 Asian individuals. There were equal males and females in the repaired cleft palate group, as well as five white and one Asian participant. Among the six adults with cleft palate, three had bilateral cleft lip and palate and three had cleft palate only.

The velum is an anatomically complex structure where four distinct muscles interact to achieve velopharyngeal closure during speech production and swallowing. Although the levator veli palatini is the primary palatal muscle responsible for speech, the musculus uvulae also plays an important role.

MRI was used to evaluate the morphology of the musculus uvulae in vivo of study participants. Analysis of MRI data indicated no statistically significant difference among adults with normal velopharyngeal anatomy with regard to sex or race when the effect of body size was accounted for. When compared to those with repaired cleft palate, the latter group had a significantly smaller musculus uvulae in every dimension.

“This study has provided new insights on the morphology of the musculus uvulae within a large and diverse sample of adults with normal velopharyngeal anatomy. We also learned that the musculus uvulae in individuals with repaired cleft palate are significantly shorter and about 50 percent less voluminous than those of participants in our control group,” Perry said. “Additional research is needed to understand the impact that the musculus uvulae has on velopharyngeal function, especially when dysmorphic anatomy, such as cleft palate, exists.”

“That small structure at the end of the soft palate is the uvula, from “uva” , the Latin word for grape. The word staphylorraphy, the repair (-rraphy) of the “grape” (staphylo-), describes the repair of the uvula and is a standard part of all palate repairs. However, it is unclear if an intact uvula is necessary for normal velar function,”  said Jack C. Yu, DMD, MD, MS ED, Editor of CPCJ.   “In this detailed anatomical study using MRI led by Dr. Jamie Perry, the next Editor of CPCJ starting 2020, the size and shape of this most medial longitudinal muscle is meticulously measured in live individuals. If we are ever going to truly understand how the velum works, we must have finite element models of the velopharynx. To do that, we must start with the precise shape and size of all the structures.”

To learn more about the American Cleft Palate-Craniofacial Association and cleft and craniofacial conditions, please visit acpa-cpf.org.

About the American Cleft Palate-Craniofacial Association
The American Cleft Palate-Craniofacial Association (ACPA) is a nonprofit 501(c)(3) association of interested individuals and health care professionals who treat and/or perform research on oral cleft and craniofacial conditions. Since 1943, ACPA has worked to optimize outcomes for individuals with oral cleft and craniofacial conditions through education, support, research, advocacy and interdisciplinary team care. ACPA also provides information to affected individuals and families and seeks to educate the public about facial differences through its ACPA Family Services program. For more information, please visit acpa-cpf.org.