Together those muscles produce a variety of intricate but well-controlled movements including tongue retraction
, protrusion, dorsiflexion, ventroflexion, retroflexion, shortening, elongating, elevation, and depression .
Alternatively a dysfunction of either the cricohyoideus or the stylohyoideus muscles could have impaired tongue retraction
. (1,4,5) An isolated dysfunction of other muscles of the hyoid apparatus was considered less likely due to their more secondary role in the rostro-caudal movement of the hyoid apparatus.
Creating the arch, or hump, correctly causes the tip of the tongue to slide forward into place and allows the root of the tongue to release, preventing numerous technical issues associated with tongue retraction
. Tongue retraction
can be both visible (where the tip is retracted) and invisible (where the tip is in place, and only the base is retracting), and has far-reaching effects on vocal technique.
Isolite says the shape is designed to allow for maximum tongue retraction
and better fit in a patient's mouth.
The difference arises because tongue retraction
is powered by muscles slow to contract in the cold.
Such hyperextension may also lead to tongue retraction
(Larnert & Ekberg, 1995), jaw depression (Bosma, 1992; Langley & Thomas, 1991), airway interference (Couriel et al., 1993), and a predisposition to aspiration (Carroll & Reilly, 1996; Ekberg, 1986).