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Laryngeal activity during upright vs. supine swallowing
Julie M Barkmeier1, Steve Bielamowicz, Naoya Takeda
1Laryngeal and Speech Section, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland 20892, USA. jbark@u.arizona.edu
Journal of Applied Physiology (Bethesda, Md. : 1985)
|July 23, 2002
Summary
Swallowing muscle activation timing, including the thyroarytenoid (TA) muscles, remains consistent between supine and upright positions. Gravitational forces do not appear to alter the central control of laryngeal airway protection during swallowing.
Area of Science:
- Physiology
- Biomechanics
- Neuroscience
Background:
- Human pharyngeal muscle activation during swallowing typically shows a consistent onset sequence in the upright position.
- Gravitational forces may alter bolus transit and influence laryngeal muscle activation timing and airway protection during swallowing, particularly in the supine position.
Purpose of the Study:
- To investigate whether laryngeal muscle onset timing during swallowing differs between the supine and upright body positions.
Main Methods:
- Nine subjects participated in the study.
- Simultaneous electromyographic (EMG) recordings of the submental complex (SMC) and thyroarytenoid (TA) muscles were obtained.
- Subjects performed swallowing trials with a 2-ml water bolus in both supine and upright positions.
Main Results:
- The timing, amplitude, and duration of thyroarytenoid (TA) muscle activation did not vary relative to the submental complex (SMC) regardless of body position.
- The onset sequence of TA muscle activation relative to the SMC during swallowing remained consistent.
Conclusions:
- Gravitational influences do not appear to affect the central timing control of laryngeal muscle activation during swallowing.
- The sequence of thyroarytenoid (TA) muscle activation relative to the submental complex (SMC) is invariant to body position during liquid swallowing.