ABSTRACT
The 1:1 SVT required descent of the larynx and shortening of the face. As the larynx was left unprotected in the new, elongated oropharynx, the tongue, which is flat in most animals and generally restricted to the oral cavity, became rounded and rotated posteriorly into the oropharynx. This facilitates speech and protects the larynx during swallowing, but when man falls asleep and the muscles relax, the tongue falls into the oropharynx and obstructs the airway. Sleep apnea then ensues (6).
