Investigation of the salpingopharyngeus (Perta et al., 2021)

Purpose: The aim of the study was to update our information regarding the salpingopharyngeus (SP) muscle using cadaveric and in vivo magnetic resonance imaging (MRI) data. Primary objectives were to (a) observe the presence/absence of the muscle and (b) quantify and describe its dimensions and course.

Method: SP specimens from 19 cadavers (10 women, nine men) were analyzed. Following head bisection, measurements of SP, including width of the cartilaginous attachment (CW) and width of the superior muscle base (SMW), were taken before and after removal of the overlying mucosa. In addition SP was analyzed in 15 healthy subjects (eight men, seven women) using high-resolution three-dimensional MRI data. CW and SMW measures were replicated in the paraxial MRI view.

Results: The presence of the salpingopharyngeal fold and muscle was confirmed bilaterally in all cadaveric and living subjects. Following mucosa removal, mean cadaveric CW and SMW measurements were 5.6 and 3.8 mm, respectively. Mean in vivo CW and SMW were 6.1 and 3.7 mm, respectively. Results from the hierarchical regression analyses revealed that, in both cadaveric and living groups, SMW is dependent on the relationship between age and body weight, after controlling for sex.

Conclusions: The salpingopharyngeal fold and SP muscle are always present bilaterally and can be quantified at the superior origin using both cadaveric and in vivo three-dimensional MRI data. Though both the superior origin and inferior course of SP are highly variable, the size of the SP muscle is dependent on characteristics known to affect muscle fibers, such as the relationship between age and body weight. Given the consistent and quantifiable presence of the SP muscle, its potential role in velopharyngeal function for speech and swallowing is reconsidered.

Supplemental Material S1. Parasagittal images of Subject 1 (female) obtained at 7 mm (A) and 9 mm (B) right from the midsagittal line with labels: pharyngeal opening of eustachian tube (*), the salpingopharyngeus muscle from the origin (orange arrows) and its points of interdigitation with the pharyngeal wall (red arrows) and the palatopharyngeus muscle (green arrow).

In this subject, two small, distinct projections of SP can be seen coursing to the palatopharyngeus muscle and the pharyngeal wall. Two different points of interdigitation with the pharyngeal wall can be appreciated in Image A versus B.

Supplemental Material S2. Parasagittal images of Subject 4 (male) obtained at 13 mm (A) and 14 mm (B) left from the midsagittal line with labels: pharyngeal opening of eustachian tube (*), the salpingopharyngeus muscle from the origin (orange arrows) and its point of interdigitation with the palatopharyngeus muscle (green arrow).

In this subject, a C-shaped contour of the SP fibers from the origin can be seen along the torus tubarius. There is one distinct projection into the palatopharyngeus muscle, terminating at a more superior point. Posterior projections of SP into the pharyngeal wall cannot be identified; rather, this case perhaps has a more lateral insertion into the pharyngeal wall that is difficult to appreciate in the parasagittal plane.

Supplemental Material S3. Parasagittal images of Subject 6 (female) obtained at 8 mm (A) and 9 mm (B) left from the midsagittal line with labels: pharyngeal opening of eustachian tube (*), the salpingopharyngeus muscle from the origin (orange arrows) and its points of interdigitation with the pharyngeal wall (red arrow), and the palatopharyngeus muscle (green arrow).

In this subject, prominent SP fibers originate on the medial aspect of the torus tubarius. Interdigitation with the pharyngeal wall and the palatopharyngeus muscle occur superiorly. The prominent bulk of the superior portion of the SP muscle appears to be similar to the cadaveric image in Figure 3A.

Supplemental Material S4. Parasagittal images of Subject 7 (female) obtained at 12 mm (A) and 13.5 mm (B) left from the midsagittal line with labels: pharyngeal opening of eustachian tube (*), the salpingopharyngeus muscle from the origin (orange arrows), and its point of interdigitation with the palatopharyngeus muscle (green arrow).

In this subject, a C-shaped contour of the SP fibers from the origin can be seen along the lateral portion of the torus tubarius. In Slice B (13.5 mm from midline), multiple orange arrows indicate the course of the muscle from the origin; in this view, more SP muscle fibers are now visible along the superior portion of the torus tubarius. Interdigitation with the palatopharyngeus muscle occurs superiorly (Slice A). The point of interdigitation with the pharyngeal wall is difficult to appreciate in this view as this may be occurring in the lateral rather than posterior dimension.

Supplemental Material S5. Parasagittal images of Subject 9 (female) obtained at 12 mm (A) and 15 mm (B) left from the midsagittal line with labels: pharyngeal opening of eustachian tube (*), the salpingopharyngeus muscle from the origin (orange arrows) and its points of interdigitation with the pharyngeal wall (red arrows) and the palatopharyngeus muscle (green arrow).

In this subject, a C-shaped contour of the SP fibers from the origin can be seen along the lateral torus tubarius. In image B, though the point of interdigitation with the palatopharyngeus muscle occurs more superiorly, two inferior points of interdigitation with the posterior pharyngeal wall can be seen – one at the oropharyngeal level and the other at the laryngopharyngeal level. This appears to be an example of a long, thin SP muscle, but distinction between SP and PP fibers remains unknown throughout the entire course.

Perta, K., Lamar, E., & Bae, Y. (2021). A cadaveric and magnetic resonance imaging investigation of the salpingopharyngeus. Journal of Speech, Language, and Hearing Research. Advance online publication. https://doi.org/10.1044/2021_JSLHR-20-00483