Differential isoform expression of SERCA and myosin heavy chain in hypopharyngeal muscles

Neuromuscular Specializations of the Human Hypopharyngeal Muscles

The hypopharyngeal muscles in humans play a vital role in swallowing, speech, and respiration. Increasing evidence indicates that these muscles are specialized to perform life-sustaining upper aerodigestive functions. This review aims to provide current knowledge regarding the key structural, physiological, and biochemical features of the hypopharyngeal muscles, including innervation, contractile properties, histochemistry, biochemical properties, myosin heavy chain (MyHC) expression and regulation, and age-related alterations. These would clarify the unique neuromuscular specializations of the human hypopharyngeal muscles for a better understanding of the functions and pathological conditions of the pharynx and for the development of novel therapies to treat related upper airway disorders.

Tongue muscle strength affects posterior pharyngeal wall advancement during swallowing: A cross-sectional study of outpatients with dysphagia

Background

Tongue muscle strength is important for swallowing but decreases with age, in association with reduced skeletal muscle mass. However, the relationships between pharyngeal dynamics and both skeletal muscle mass and tongue muscle strength are unknown.

Objective

To investigate the effect of reductions in tongue muscle strength on pharyngeal movement during swallowing in patients with dysphagia.

Methods

Subjects were selected from male outpatients ≥65 years old who were examined for the main complaint of dysphagia. Patients with history of neurodegenerative disease affecting tongue movement, cerebrovascular disease or oral cancer were excluded. As a result, 82 men (mean age, 80.6 ± 6.8 years) participated. Skeletal muscle mass index (SMI) as physical parameters and maximum tongue pressure (MTP) as tongue muscles strength were measured. Status and dynamics of the pharyngeal organs, including change in posterior pharyngeal wall advancement (PPWA) when swallowing 3.0 mL of moderately thick liquid, were measured by analysing videofluoroscopic images. Simple bivariate correlation and multiple regression analysis were used to statistically analyse correlations between parameters.

Results

MTP showed a significant positive correlation with SMI (r = .43, P < .01). PPWA showed a significant negative correlation with MTP (r = −0.30, P < .01), but no association with SMI.

Conclusions

While tongue muscle strength is affected by skeletal muscle mass, posterior pharyngeal wall advancement is not readily affected by decreases in skeletal muscle mass. Posterior pharyngeal wall advancement may increase to compensate for swallowing function among individuals with reduced tongue muscle strength.