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Influence of tongue muscle contraction and transmural pressure on nasopharyngeal geometry in the rat.
- Source :
-
Journal of applied physiology (Bethesda, Md. : 1985) [J Appl Physiol (1985)] 2011 Sep; Vol. 111 (3), pp. 766-74. Date of Electronic Publication: 2011 Jun 30. - Publication Year :
- 2011
-
Abstract
- The mammalian pharynx is a hollow muscular tube that participates in ingestion and respiration, and its size, shape, and stiffness can be altered by contraction of skeletal muscles that lie inside or outside of its walls. MRI was used to determine the interaction between pharyngeal pressure and selective stimulation of extrinsic tongue muscles on the shape of the rat nasopharynx. Pressure (-9, -6, -3, 3, 6, and 9 cmH₂O) was applied randomly to the isolated pharyngeal airway of anesthetized rats that were positioned in a 4.7-T MRI scanner. The anterior-posterior (AP) and lateral diameters of the nasopharynx were measured in eight axial slices at each level of pressure, with and without bilateral hypoglossal nerve stimulation (0.1-ms pulse, 1/3 maximal force, 80 Hz). The rat nasopharynx is nearly circular, and positive pharyngeal pressure caused similar expansion of AP and lateral diameters; as a result, airway shape (ratio of lateral to AP diameter) remained constant. Negative pressure did not change AP or lateral diameter significantly, suggesting that a negative pressure reflex activated the tongue or other pharyngeal muscles. Stimulation of tongue protrudor muscles alone or coactivation of protrudor and retractor muscles caused greater AP than lateral expansion, making the nasopharynx slightly more elliptical, with the long axis in the AP direction. These effects tended to be more pronounced at negative pharyngeal pressures and greater in the caudal than rostral nasopharynx. These data show that stimulation of rodent tongue muscles can adjust pharyngeal shape, extending previous work showing that tongue muscle contraction alters pharyngeal compliance and volume, and provide physiological insight that can be applied to the treatment of obstructive sleep apnea.
- Subjects :
- Animals
Biomechanical Phenomena
Electric Stimulation
Hypoglossal Nerve physiology
Magnetic Resonance Imaging
Male
Muscle, Skeletal innervation
Pressure
Rats
Rats, Sprague-Dawley
Reflex
Tongue innervation
Muscle Contraction
Muscle, Skeletal physiology
Nasopharynx anatomy & histology
Tongue physiology
Subjects
Details
- Language :
- English
- ISSN :
- 1522-1601
- Volume :
- 111
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- Journal of applied physiology (Bethesda, Md. : 1985)
- Publication Type :
- Academic Journal
- Accession number :
- 21719721
- Full Text :
- https://doi.org/10.1152/japplphysiol.01501.2010