The Superior Constrictor Muscle: A Key Component of Velopharyngeal Function

Velopharyngeal insufficiency is a common phenomenon that can lead to speech difficulties and other orofacial disorders in individuals with velocardiofacial syndrome (VCFS). One of the key muscles involved in velopharyngeal function is the superior constrictor muscle, also known as the SPC muscle. This muscle plays a crucial role in movement of the lateral and posterior pharyngeal walls, which are essential for proper speech and swallowing.

The SPC muscle is a complex structure that arises from the medial pterygoid plate and hamulus, and extends from the pharyngeal tubercle of the skull superiorly to approximately the level of the third cervical vertebra inferiorly. Its fibers then curve posteriorly to insert into the median raphe of the pharynx.

Recent studies have suggested that abnormalities in the SPC muscle may contribute to the hypotonia and hypernasal speech often seen in individuals with VCFS. For example, Golding-Kushner et al. (2003) found a decrease in the thickness of the posterior pharyngeal wall on plain radiographs in patients with VCFS.

To better understand the role of the SPC muscle in velopharyngeal function, researchers have used various techniques to evaluate its thickness, histology, and histochemistry. One such technique is enzyme-histochemical analysis, which involves staining specimens for demonstration of myofibrillar adenosine triphosphatase (ATPase) activity.

The purpose of this study was to evaluate the thickness, histology, and histochemistry of the SPC muscle in patients with VCFS, and to determine whether a muscle irregularity exists that might contribute to the hypotonia seen in these patients. Our results suggest that the SPC muscle is indeed abnormal in individuals with VCFS, which may contribute to their speech difficulties.

In conclusion, the superior constrictor muscle plays a critical role in velopharyngeal function and its abnormality can lead to speech difficulties in individuals with VCFS. Further research is needed to fully understand the mechanisms underlying this relationship and to develop effective treatments for these patients.

Superior constrictor muscle