Surgical approach to the thyroarytenoid branch of the inferior laryngeal nerve through the thyroid cartilage

Abstract

Brazil. Scientific, intelectual, conception and design of the study; manuscript preparation; critical revision; final approval. ABSTRACT PURPOSE:To describe the anatomical course of the intralaryngeal portion of the inferior laryngeal nerve (ILN) and to standardize the surgical access to its thyroarytenoid branch (TAb) through the thyroid cartilage. METHODS:Under surgical microscopy, 33 adult human excised larynges were dissected, to expose the intralaryngeal portion of ILN. The point of entry of TAb, ILN's terminal branch, in the thyroarytenoid (TA) muscle was determined and correlated with thyroid cartilage dimensions. RESULTS:After entering the larynx, the ILN consistently traveled between the thyroid cartilage and the lateral cricoarytenoid muscle in an anterior and slightly cranial course. The distance from the point of entry of the TAb in the TA muscle to the midline (TAb-H) and to the inferior border (TAb-V) of the thyroid cartilage differed according to gender. In females, mean distances of TAb-H and TAb-V were 20.5mm and 5.2mm and in males, 22.3mm and 5.9mm, respectively. CONCLUSION:The intralaryngeal course of the inferior laryngeal nerve presents low variability and measures from landmarks in the thyroid cartilage help to estimate the point of entry of thyroarytenoid branch in thyroarytenoid muscle.

Isolated Paresis of Laryngeal Adduction: What Are the Laryngoscopic and Stroboscopic Findings?

“…An interesting finding in the present study was that paralysis of the TA muscle was associated with impaired adduction of the ipsilateral ventricular fold in all patients. This finding suggests that in these cases, either the TA muscle was the main muscle responsible for ventricular fold adduction, or the innervation of the ventricularis muscle is closely related to the terminal branch of the recurrent laryngeal nerve that innervates the TA muscle . We further speculate that the asymmetric supraglottic pulling forces that act over the arytenoids during phonation may be responsible for the deviation of the interarytenoid region toward the side opposite to the paralysis, the stronger side, as seen in most of our patients (Figs.…”

“…The terminal branch of the inferior laryngeal nerve innervates the thyroarytenoid (TA) muscle after sending branches to the lateral cricoarytenoid (LCA) muscle . If both muscles are paralyzed, a condition referred to as vocal fold adductor paralysis develops, leading to impairment of vocal fold adduction, with preserved abduction .…”

“…[3][4][5] The terminal branch of the inferior laryngeal nerve innervates the thyroarytenoid (TA) muscle after sending branches to the lateral cricoarytenoid (LCA) muscle. 6 If both muscles are paralyzed, a condition referred to as vocal fold adductor paralysis develops, leading to impairment of vocal fold adduction, with preserved abduction. 7,8 However, if the neurological compromise is restricted to the TA muscle or there is limited impairment of other adductors (LCA and arytenoid muscles), the mobility of the glottis may be preserved, whereas vocal fold vibration may be disturbed.…”

Anatomical Course of the Thyroarytenoid Branch of the Recurrent Laryngeal Nerve

“…Scheid et al reported branching of the TA nerve in 20% of the specimens . According to Sperandio et al, the nerve ending of the TAb was like a brush in 58 cases (88%) and like a unique branch in eight cases (12%) . We did not trace the nerve to its insertion into the muscle.…”

“…21 According to Sperandio et al, the nerve ending of the TAb was like a brush in 58 cases (88%) and like a unique branch in eight cases (12%). 5 We did not trace the nerve to its insertion into the muscle. Branching was seen within the cartilage window in eight larynges (17.39%).…”