Contraction Properties of Intrinsic Laryngeal Muscles

Abstract

The contraction times of laryngeal muscles in the dog were found to differ from 14 and 16 msec for the thyroarytenoid and lateral cricoarytenoid muscles to 30 and 35 msec for the posterior cricoarytenoid and the cricothyroid muscles respectively. The same relation between the contraction times of fast and slow muscles was characteristic also of some other species investigated. The view is advanced that the short contraction time of the two sphincter girdle muscles primarily serves the purpose of closing the laryngeal aperture in protective larynx reflexes. The thyroarytenoid and cricothyroid muscles of dog, chosen as representatives of fast and slow muscle, were subjected to a more detailed analysis. Determinations of the active state plateau by the method of superimposition of tension curves from one and two stimuli gave values of 3.0–4.0 msec for the thyroarytenoid and 3.5–4.5 msec for the cricothyroid muscle. After determinations of the tetanus‐twitch ratios for the two muscles, the rate of decay of the active state could be estimated and was shown to be faster in the thyroarytenoid muscle. Tetanic direct stimulation showed that complete fusion may not occur until above 300 per sec in the cricothyroid and above 400 in the thyroarytenoid muscle. Analogous analyses performed by indirect stimulation of the fast and slow muscle gave very similar results with respect to mechanical separation time and fusion frequency. The results from an action potential analysis during short‐interval nerve stimulation are discussed from the point of view of the active state conception.

Fibre architecture and song activation rates of syringeal muscles are not lateralized in the European starling

“…Laryngeal muscles in mammals are fast, but do not reach such high contraction rates as starling muscles (Martensson and Skoglund, 1964;Alipour-Haghighi et al, 1987;Alipour and Titze, 1999;Sciote et al, 2002;Hoh, 2005). Unlike toadfish sonic and rattlesnake tailshaker muscles, laryngeal muscles show heterogeneous fibre type composition (Hoh, 2005).…”

The myosin light chain 1 isoform associated with masticatory myosin heavy chain in mammals and reptiles is embryonic/atrial MLC1

“…Extraocular/laryngeal MHC has been referred to as 'superfast' myosin in some reports, but this is a different protein, encoded by a different gene, and the label was intended to refer to the presumed high velocity of shortening in extraocular and laryngeal muscle fibers in which it is expressed (Briggs and Schachat, 2000;Shiotani and Flint, 1998) and knowing that these muscles can generate force at relatively high rates (e.g. Cooper and Eccles, 1930;Brown and Harvey, 1941;Bach-y-Rita and Ito, 1966;Martensson and Skoglund, 1964;Hall-Craggs, 1968).…”

Active and Passive Properties of Canine Abduction/Adduction Laryngeal Muscles

“…The active and passive properties of two laryngeal muscles, the TA and CT, are well documented. [16][17][18][19][20][21][22][23][24][25] However, data on active and passive properties of other laryngeal muscles are still scarce. Only the twitch contraction of PCA muscle has been investigated due to its importance as the sole abductor in speech and respiration.…”

“…Only the twitch contraction of PCA muscle has been investigated due to its importance as the sole abductor in speech and respiration. 17,19,26,27 The muscle twitch is a fundamental unit of contraction from which any tetanic contraction can be derived through the summation of the twitch forces that are separated by a randomized activation delay. This delay is based on means and standard deviation of motor unit firing frequencies as described and modeled by Titze.…”