| Anterior boundary | Posterior boundary | Superior boundary | Inferior boundary |
---|---|---|---|---|
Nasal cavity | Line connecting the ANS to the tip of the nasal bone | Line extending from S to the PNS | Line connecting N to S | Line extending from ANS to PNS |
Nasopharynx | Line extending from S to the PNS | Line extending from S to the tip of the odontoid process | Line extending from S to the tip of the odontoid process | Line extending from PNS to the tip of the odontoid process |
Oropharynx | Line extending from PNS to the tip of the epiglottis | Line extending from the tip of the odontoid process to the posterior superior border of CV4 | Line extending from PNS to the tip of the odontoid process | Line extending from the base of the epiglottis to the posterior superior border of CV4 |
Hypopharynx | Line extending from the base of the epiglottis to the inferior border of the symphysis | Line extending from the posterior–superior corner of CV4 to the posterior–inferior corner of CV4 | Line extending from the base of the epiglottis to the posterior superior border of CV4 | Line extending from the posterior–inferior corner of CV4 to the inferior border of the symphysis |