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Reciprocal activation of hypopharyngeal muscles and their effect on upper airway area. J Appl Physiol (1985) 2000 Feb;88(2):611-26



Pubmed ID




Scopus ID

2-s2.0-0033975937   18 Citations


We examined in awake goats, 1) with intact upper airways (UAW), the effect of altering chemical drive on pharyngeal constrictors [thyropharyngeus (TP) and hypopharyngeus (HP)] and a dilator [stylopharyngeus (SP)], and 2) with an isolated UAW, the effect of activation of these muscles on supraglottic UAW (UAW(SG)) area. During eupnea in nine goats with intact UAW, the TP and HP were active during expiration, whereas the SP exhibited tonic expiratory and phasic inspiratory activity. After mechanically induced apneas (MIA), TP activity increased (263%, P < 0.02), HP activity exhibited a small, varied response, and SP activity greatly decreased (10%, P < 0.02). During resumption of respiratory effort, all goats exhibited absent/reduced airflow, and when diaphragm activity was 95% of control, TP activity remained elevated (135%) and SP activity was reduced (56%, P < 0.02). During hypercapnia, 1) TP activity decreased (P < 0.02), 2) HP response varied, and 3) SP activity increased (P < 0.02). After MIA in six goats with isolated UAW, TP activity increased 198% (P < 0.02) and UAW(SG) area (endoscopically determined) decreased (to 15% of control, P < 0.02). During recovery from MIA, a correlation was found between UAW(SG) area and the ratio of SP to TP activity. We conclude that the reciprocal activation of mechanically opposing dilator and constrictor muscles in the hypopharynx is correlated to changes in the UAW(SG) area, and an imbalance in activity of these opposing muscles can lead to UAW(SG) narrowing.

Author List

Feroah TR, Forster HV, Pan LG, Rice T


Hubert V. Forster PhD Professor in the Physiology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Analysis of Variance
Muscle Contraction
Pharyngeal Muscles
Respiration, Artificial
Respiratory Mechanics
jenkins-FCD Prod-466 5b81815b8b3d1f46bfec16512ed5f574613f59c5