2012 Volume 16 Issue 3 Pages 269-275
[Purpose] Neck angle and body posture are known to influence swallowing; however this influence has not been sufficiently clarified. Previous reports investigating this influence have considered the anatomical viewpoint, but not muscular activity, of the pharynx. This study aimed to clarify the influence of a change in neck angle on the activity of pharyngeal and neck muscles.
[Method] We evaluated 19 healthy adult men (aged 25-46 years; mean, 32.5 years). The seated participants were made to swallow 5 cc of water while holding the neck in 5 conditions of median and flexion (20 and 40 degrees) and extension (20 and 40 degrees), and the suprahyoid, infrahyoid, and sternocleidomastoid muscle activities were measured through surface electromyography; the duration of muscle activity and muscle integration value were also estimated.
[Result] Although the muscle activity of the suprahyoid and infrahyoid muscles significantly increased duration at 40 degrees of extension compared with the other angels, the muscle activity of the sternocleidomastoid muscle did not significantly differ at any of the angles. Moreover, the suprahyoid, infrahyoid and sternocleidomastoid muscles showed a higher muscle integration value at 40 degrees of extension than at other angles.
[Conclusion] Although, muscle activity could indicate that swallowing was difficult at 40 degrees of extension, the effect of neck flexion could not be confirmed. The activity of the suprahyoid, infrahyoid and sternocleidomastoid muscles during swallowing changes with an alteration in the neck angle. Therefore we suggest the importance of the evaluation of the range of motion for flexion and extension as well as suitable intervention in patients with dysphagia.
