There are many factors that can influence the "laryngeal posture" as the larynx is a suspended organ that is affected by all the influences given to it by the systems connected to it directly or via long channels. Precisely for this reason, when carrying out a manual positional and biomechanical assessment it is best to evaluate the individual in his totality and complexity. Many call this an ergonomic assessment of the individual. This concept is all the more true the more we deal with professional, artistic or singers' voices who accompany themselves by playing an instrument. Generally, the joints of greatest interest for the laryngeal structure are the shoulders. If these were to be found, for example, in elevation or internal rotation, they could be related to an imbalance of the rhomboids, middle and upper trapezius, pectorals, scalenes or SCM. You can already see how careful evaluation of the patient is necessary.
Moving on to a laryngeal evaluation as described by the Lieberman protocol (Laryngeal Manipulation, 2000) which is the one currently validated, we can define general lines of dysfunction, which must then be ascertained and confirmed by the osteopathic professional.
Laryngeal positional dysfunctions:
A. Escape of a posterior horn of the hyoid: the hyoid could be in a side bending position or rotation on that side, perhaps due to a traction of the lingual and/or masticatory chain which brings it into a submandibular position with shortening of the suprahyoids. Consequence: conditioning of chordal mobility by shear stress (Ingo Titze, 1994) through torsion and pressure on the laryngeal structures such as the thyroid and/or cricoid cartilage. Palpation: posterior horn of the hyoid receding on that side, hypertonicity of the ipsilateral suprahyoids, or of the subhyoids due to an attempt to maintain the correct position; shortening of the pharynx constrictor and/or ipsilateral thyroarytenoid.
B. Reduction or absence of the thyrohyoid space: this dysfunctional picture, often associated with pain, is related to shortening and hypertonicity of the thyrohyoid muscle which limits laryngeal mobility in inferiority and of the hyoid in superiority.
C. Limitation of mobility of the cricothyroid visor: this area, determined by the mobility of the cricothyroid joint and the individual arytenoid mobilities, if altered in opening can limit the acute emission, if instead limited in closure it can limit a low sound. The functional limitation is related to cricothyroid hypertonicity, associated or not with sternothyroid and sternohyoid shortening. Possible pain on palpation.