Electromyographic study on respiratory movements of the intrinsic laryngeal muscles.

The electromyographic activity of intrinsic laryngeal muscles during quiet breathing in the anaesthetized horse

“…Howeve.r, in contrast to Faaborg Anderson's human findings, the electrical activity in the horse increased during· in spiration. Similar electrical bethaviour during quiet respiration in this muscl<:: has been observed in anaesthetized cats (Green and Neil, 1955;Rex, 1969;Suzuki and Kirchner, 1969), dogs (Nakamura et al, 1958;Siribodhi et al, 1963) and goats (Murtagh and Campbell, 1954) but in these. species the activity ceased during expiration.…”

“…This finding is hard to equate with the opinion of most authors that the cricothyroid muscle is an adduc tor muscle of the larynx (Murtagh, 1945;Seymour and Henry, 1954;Faaborg Anderson, 1957;Siribodhi et al, 1963;Nakamura et al, 1958). Rather it is more in accord with the opinion of Hiroto et al (~964) and Suzuki et al (1970) who conSidered that the cricothyroid assisted ~he dorsal crico-arytenoid muscle in open-109 the ~lottic chink during inspiration.…”

“…Numerous authO'rs consider it to' be most active during expiration (Mur tagh and Campbell, 1954;Tschiassny 1944; Nakamura et at., 1958;Siribodhi et aI., 1963;Shin et at., 1969;Suzuki et ai., 1970) whilst others consider it to be most active during inspiration (Andrew 1955· Armstrong andSmith, 1955;F~borg: Anderson, 1957;Hiroto et al, 1964).…”

“…For example, in the anaesthetized dog Nakamura et al (1958) reported that th~ cricothyroid and the adductor muscles remained silent throughout the rest phase of the respiratory cycle. Suzuki et al (1970) reported that the cricothyroid activity during quiet respiration in cats under general anaesthesia was so weak that it could be observed only when the anaesthesia was very light.…”

“…Electromyographic examination of in trinsic laryngeal muscular activity has been carried out in man (Faaborg Anderson, 1957) and some experimental animals including the cat (Green and Neil, 1955;Rex, 1969), dog (Nakamura et al, 1958;Siribodhi et al, 1963), goat (Murtagh and Campbell, 1954) and mon key (Lund and Palmer, 1969). The pur pose of these investigations has been to increase understanding of the action of the laryngeal muscles and to provide: a basis on which to compare the normal individual with those suffering from neurogenic and myogenic disorders of the larynx.…”