The demarcation line between the nasopharynx and oropharynx is in the plane of the free edge of the soft palate, and the plane above the skull base and the plane of the free edge of the soft palate is called the nasopharynx. In the nasopharynx, there are mainly adenoids, also known as pharyngeal tonsils, which obstruct the nasopharyngeal cavity and affect nasal breathing. On both sides, there is also the pharyngo-pharyngeal opening, and the adenoids compress the pharyngo-pharyngeal opening, causing hearing loss and, in severe cases, oozing otitis media. There are also pharyngeal tonsils, as well as the pharyngeal fossa, which is a good site for nasopharyngeal cancer. The oropharynx is the area between the soft palate and the plane of the superior epiglottis, that is, the area that can be seen by opening the mouth, mainly the uvula, the free edge of the soft palate, the posterior pharyngeal wall directly opposite, the dorsum of the tongue, the lingual-palatal arch on both sides, the pharyngeal-palatal arch, and the palatal tonsils on both sides, and the narrowing of these parts causes obstructive sleep apnea syndrome.