Electrical activity from the superior pharyngeal constrictor during reflexive and nonreflexive tasks

Area of Science:

• Anatomy and Physiology
• Biomechanics of Speech and Swallowing

Background:

• The superior pharyngeal constrictor muscle plays a role in swallowing.
• Understanding its activation during non-swallowing tasks is crucial for clinical applications.

Purpose of the Study:

• To quantitatively assess the activation of the superior pharyngeal constrictor muscle during various nonswallowing tasks in healthy individuals.
• To identify which voluntary and reflexive actions elicit significant muscle engagement.

Main Methods:

• Electromyography (EMG) using bipolar hooked wire electrodes in 15 healthy subjects.
• Subjects performed reflexive and voluntary phonation/nonspeech tasks.
• EMG data was processed and analyzed using ANOVA and linear modeling.

Main Results:

• Superior pharyngeal constrictor muscle activation varied with electrode placement, with highest values in lateral-superior positions.
• The muscle is primarily activated during reflexive activities, with swallowing yielding the highest EMG amplitude.
• A gag response produced approximately 60% of the activity seen during swallowing.
• Production of the phoneme /k/ in "hok" and a sustained hard /k/ (modified Valsalva) showed the next highest EMG levels.

Conclusions:

• The superior pharyngeal constrictor muscle is predominantly activated reflexively.
• Specific voluntary tasks, particularly those involving the /k/ sound or forceful exhalation, can significantly engage this muscle.
• Findings contribute to understanding pharyngeal muscle function beyond deglutition.