Increasing tongue-to-palate pressure coincides with increased muscle activity. Activation of the floor-of-mouth, tongue, and jaw closing muscles increased tongue-to-palate pressure. These findings support the use of a tongue-press exercise to strengthen floor-of-mouth muscles, tongue, and jaw-closing muscles.

Submental surface electromyographic recordings are commonly used in the investigation of swallowing disorders. The measured electromyography is thought to reflect the actions of floor-of-mouth muscles. Although this is a reasonable assumption, to date there have been no investigations to delineate which muscles contribute to this surface recording. The primary goal of this experiment was to determine which muscles contribute most to the submental surface. Electromyography was recorded simultaneously from the submental surface as well as from five individual muscles: mylohyoid, anterior belly of the digastric, geniohyoid, genioglossus and platysma. Three analysis methods were performed to estimate individual muscle contributions: correlation, numeric, and analytic. For the numeric and analytic analyses, a linear model was defined and used to represent the relationship between the surface and intramuscular recordings. Muscles that received a high correlation, numeric and/or analytic value were considered to be primary contributors to the submental recording. Regardless of analysis approach, the primary contributions to the submental surface recording were the mylohyoid, anterior belly of the digastric, and the geniohyoid muscles. Contributions from the genioglossus and the platysma muscles were minimal. Contributions as a function of bolus volume and viscosity are also discussed.

A sour bolus has been used as a modality in the treatment of oropharyngeal dysphagia based on the hypothesis that this stimulus provides an effective preswallow sensory input that lowers the threshold required to trigger a pharyngeal swallow. The result is a more immediate swallow onset time. Additionally, the sour bolus may invigorate the oral muscles resulting in stronger contractions during the swallow. The purpose of this investigation was to compare the intramuscular electromyographic activity of the mylohyoid, geniohyoid, and anterior belly of the digastric muscles during sour and water boluses with regard to duration, strength, and timing of muscle activation. Muscle duration, swallow onset time, and pattern of muscle activation did not differ for the two bolus types. Muscle activation time was more tightly approximated across the onsets of the three muscles when a sour bolus was used. A sour bolus also resulted in a stronger muscle contraction as evidenced by greater electromyographic activity. These data support the use of a sour bolus as part of a treatment paradigm.

Reflex laryngeal adduction is a component of both the laryngeal chemoreflex and the esophagolaryngeal adductor reflex, two life-threatening reflexes that occur in immature animals. These two reflex responses are also thought to exist in infants and may play a role in causing life-threatening laryngospastic events and perhaps sudden infant death syndrome. Identifying neurotransmitters that mediate laryngeal adduction is important to understanding the mechanism of reflex laryngeal responses and to identifying potential means of pharmacologic prevention. Substance P (SP), a tachykinin, putatively functions as a sensory neurotransmitter and may play a role in mediating laryngeal reflexes. Substance P-immunoreactive-like fibers and receptors are present in the subepithelial tissues of the larynx, the vagus nerves, the nodose and jugular ganglia, and the vagal brain stem nuclei. In this investigation, the effect of SP infusion on laryngeal motor activity in an in vivo model is reported. Substance P was infused intravenously into 8 puppies (20 to 133 days of age, mean 81.2), on a mean of 3.0 occasions (range 1 to 6). Cardiovascular, respiratory, arterial blood gas, and cricothyroid (CT), thyroarytenoid (TA), and genioglossus electromyographic (EMG) responses to infusion of the tachykinin were recorded and subsequently analyzed. The SP infusion induced a marked increase in CT or TA EMG activity in 23 of 24 studies, and the increase was typically apparent within 60 seconds of the infusion. An increase in genioglossus EMG activity did not occur. An immediate, profound decrease in mean arterial pressure and an increase in respiratory rate and depth of chest wall excursion accompanied the laryngeal response. Arterial blood gas values remained unchanged (p > .05). The laryngeal adductor response to SP infusion was blocked when animals were pretreated with a systemic SP antagonist (Pfizer CP-96,345). This study demonstrates that peripheral infusion of the tachykinin SP induces a marked increase in laryngeal adductor activity. The response may be blocked by pretreatment of animals with a systemic SP antagonist. Because SP is thought to act primarily as a sensory neurotransmitter, these findings may be important in understanding the mechanism of reflex laryngeal adductor responses.

Waveform morphology of electromyographic signals registered from both electrode types show similar complex action potentials. There is no difference between the hooked-wire electrode and the concentric needle electrode in terms of electrode stability or vocal fold injury in the thyroarytenoid muscle after large-scale laryngeal movements.