The dot is the retrolingual airway, which is very narrow. The thin arrow is the unusual v shaped epiglottis of the larynx (voice box). The thick arrow is pointing at the lingual tonsil, on the very back surface of the tongue, low down in the throat.
Together, the v shaped epiglottis and enlarged lingual tonsil, plus inherited normal growth patterns of mandible and tongue mean that the retrolingual airway (the dot) is very narrow. Add some weight gain particularly around the neck and this will almost inevitably cause snoring and sleep apnoea.