Describe the anatomy and clinical importance of the nasopharynx.

The Nasopharynx

• The nasopharynx lies behind the nasal cavity and above the soft palate, extending from the choanae in front to the posterior pharyngeal wall behind, and from the skull base above to the level of the soft palate below.
• It is a respiratory passage, lined largely by ciliated columnar epithelium.
• Its roof and posterior wall are formed by the body of the sphenoid and the basiocciput, and carry the adenoid (nasopharyngeal tonsil)
• The lateral wall is the clinically critical area, bearing the eustachian tube opening, the torus tubarius (the cartilaginous elevation behind it), and the fossa of rosenmuller
• The fossa OF rosenmuller is the single most important site in the nasopharynx: a recess behind and above the torus tubarius, and the commonest site of origin of nasopharyngeal carcinoma
• Because it is a deep, blind recess, a tumour there is hidden and grows silently — obstructing the Eustachian tube long before it causes any nasal symptom
• The clinical rule that follows IS the one TO remember: a unilateral middle ear effusion in an adult is nasopharyngeal carcinoma until the postnasal space has been endoscoped. The effusion is frequently the only symptom, and is the earliest
• The adenoid is a mass of subepithelial lymphoid tissue without a capsule or crypts (unlike the palatine tonsil), forming part of waldeyer’S ring
• It enlarges from infancy to 5 or 6 years and then atrophies, being insignificant after puberty — which is why an adenoidal mass in an adult is abnormal and must be biopsied
• Adenoid hypertrophy causes — nasal obstruction and mouth breathing; snoring and obstructive sleep apnoea; Eustachian obstruction with otitis media with effusion and recurrent acute otitis media; rhinolalia clausa; and the adenoid facies — an open mouth, prominent upper incisors, a high arched palate, a shortened upper lip, a pinched nose and a vacant expression
• Nerve supply is from the pharyngeal plexus, with the maxillary nerve (V2) via the pharyngeal branch; and lymphatic drainage is to the retropharyngeal and upper deep cervical nodes
• The lymphatic drainage explains the commonest presentation OF nasopharyngeal carcinoma — a painless upper cervical node.
• Other lesions of the nasopharynx — juvenile nasopharyngeal angiofibroma in an adolescent male, presenting with profuse recurrent epistaxis and obstruction, which must never be biopsied because of catastrophic haemorrhage; thornwaldt cyst, a midline remnant of the notochordal tract causing postnasal discharge and halitosis; antrochoanal polyp presenting through the choana; lymphoma; and chordoma