Morphology of the Levator Veli Palatini Muscle Using Magnetic Resonance Imaging

Abstract

Background No studies have reported the circumference and diameter of the levator veli palatini muscle at multiple points along its length and from both views (frontal and lateral). The purpose of this study was to provide quantitative data regarding the levator muscle morphology along the length of the muscle using magnetic resonance imaging and advanced three-dimensional computer technology. Methods Ten Caucasian male subjects participated in the study. Subjects were scanned using a Siemens 3 T Trio. Levator muscle measures were obtained using a two-dimensional image plane. A three-dimensional model was used to measure the circumference and muscle diameter (in two directions) at six points along the length of the levator muscle. Results Levator muscle length ranged from 41.67 mm to 52.85 mm across all subjects. Mean extravelar muscle length was 30.55 mm (SD, 2.8 mm) and 30.01 mm (SD, 2.9 mm) for right and left muscles. The mean circumference at the origin was 18.90 mm (SD, 2.6 mm). At the second point, the muscle circumference mean increased slightly (mean, 22.40 mm; SD, 4.9 mm). The means for the remainder of the measures (points 3, 4, 5, and 6) were consistent, showing little to no change. Conclusion Circumference and diameter values were similar to those reported in previous literature. The muscle did diverge at the point where the muscle bundle entered the velum, as it has been previously described. Instead, the muscle diverges near the midline insertion becoming sparser (smaller superior-to-inferior diameter).

A Computational Model of Velopharyngeal Closure for Simulating Cleft Palate Repair

“…The LVP of infants is approximately two-thirds of the length of the LVP of adults. 13,20,24,25 This suggests that scaling down the simulated overlap distances for surgeries on infants and children would produce the same mechanical effects on closure force. Estimated overlap amounts for adults and infants based on the overlap percentages from this study are shown in Table 2.…”

“…The dimensions LVP muscle and the soft palate were determined from published measurements collected from adult magnetic resonance (MR) images (Table 1). 13,18,20,21,27,28 The curve that describes the shape of the posterior pharyngeal wall was defined based on outlines defined on midplane sagittal MR images of the soft palate Osirix software (Pixmeo, Geneva, Switzerland). 27 The initial distance between the soft palate and posterior wall was defined based on a straight-line measurement, in the relaxed position.…”

“…However, it has also been suggested that separation of the levator ends may also be possible in cleft palate patients after surgery and that the amount of separation may be dependent on the type of surgery. 13 A more recent procedure that emphasizes aggressive LVP overlap has shown very promising results in prevention of VPI. 14 The extent of muscle overlap has been thought to contribute significantly to speech outcomes owing to the reconstruction of the LVP sling, 10 yet the mechanism and extent of this contribution are poorly understood.…”

Racial Variations in Velopharyngeal and Craniometric Morphology in Children: An Imaging Study

“…It has been established that understanding normal anatomy is necessary in evaluating and determining dysmorphic anatomy (Perry et al, 2013). As such, there is a need for continued research regarding the anatomy and function of the velopharyngeal mechanism.…”

“…Studies have demonstrated the use of MRI in assessing levator muscle characteristics in adults with normal velopharyngeal anatomy (Bae, Kuehn, Sutton, Conway, & Perry, 2011;Ettema et al, 2002;Perry, Kuehn, & Sutton, 2013) as well as in adults with repaired cleft palate and hypernasal speech (Ha, Kuehn, Cohen, & Alperin, 2007). Ha et al (2007) reported that participants with residual hypernasality demonstrated levator muscle dimensions that were different from levator muscle features in adults without cleft palate.…”