The clinical interest of the ary‐thyro‐cricoid fascicle

Abstract

The aim of this work was to study the prevalence and form of the ary-thyro-cricoid (ATC) muscular fascicle, a variable muscular slip connecting the oblique and/or transverse arytenoid muscles with the thyroarytenoid (TA) and/or lateral cricoarytenoid (LCA) muscles resembling a sphincter encircling the glottis. Thirty larynges obtained from necropsies of individuals with no known laryngeal pathology were dissected. The ATC fascicle was observed in 96.7% of the larynges. It appeared bilaterally in 60% of subjects and unilaterally in 36.7%. The posterior attachment of the muscular slip was observed to be in common with either the transverse arytenoid (34%), or the oblique arytenoid (28%) or both muscles (38%). Its fibers terminated by intermingling with either those of the LCA muscle (10.6%), or the TA muscle (38.3%) or both (51.1%). These variable attachments mean that there are nine possible variants of this muscular fascicle. The ATC fascicle was supplied by branches originating bilaterally from the recurrent laryngeal (RLN) and internal laryngeal nerves. The existence of this ATC fascicle could explain the variable position (intermediate, paramedian or lateral) adopted by the vocal folds after lesion of the RLN. The bilateral disposition and innervation of the fascicle could also complicate the interpretation of electromyographic techniques used for testing laryngeal nerve function.

Laryngeal Muscles

“…The arythyrocricoid fascicle has been found in 96.7% of cases (60% bilaterally, 36.7% unilaterally; 20% left side, 16.7% right side) without significant side or The pharyngeal mucosa has been removed. These variable attachments mean that there are nine possible variants of this muscular fascicle (Maranillo et al 2011). Adapted from Well and Thomas (1937) with permission from John Wiley & Sons.…”

“…The external sphincter gives rise to the cricothyroid muscle, the thyroid cartilage and the inferior constrictor muscles of the pharynx; the internal sphincter is the origin of the rest of the intrinsic muscles and cartilages of the larynx (Fürbringer 1875;Kanthack 1892;Maranillo et al 2009Maranillo et al , 2011. The external sphincter gives rise to the cricothyroid muscle, the thyroid cartilage and the inferior constrictor muscles of the pharynx; the internal sphincter is the origin of the rest of the intrinsic muscles and cartilages of the larynx (Fürbringer 1875;Kanthack 1892;Maranillo et al 2009Maranillo et al , 2011.…”

“…Failure of that process can give rise to a wide range of anatomical variations (Maranillo et al 2009(Maranillo et al , 2011. Failure of that process can give rise to a wide range of anatomical variations (Maranillo et al 2009(Maranillo et al , 2011.…”

Oblique thyroarytenoid muscle in humans: An independent muscle or an accessory belly?

“…The thyroarytenoid (TA) muscle is one of the intrinsic laryngeal muscles that is known to play an important role in controlling the equality and intensity of phonation . The TA muscle draws the arytenoid cartilage toward the thyroid cartilage, thereby rotating the arytenoid cartilage medially and relaxing the vocal ligaments …”