Nasopharynx Anatomy

🌬️ What is the Nasopharynx?

The nasopharynx is the uppermost part of the pharynx, also known as the epipharynx.

📍 Location of Nasopharynx:

• Posterior to the nasal cavities.
• Above the level of the soft palate.
• Extent: From the base of the skull (basal occiput and basal sphenoid) to the horizontal plane passing through the hard palate.

🔲 Boundaries of the Nasopharynx

The nasopharynx has the following boundaries:

1. Roof

• Formed by the basiocciput and basisphenoid.
• Roof slopes backward and continues into the posterior wall.
• Nasopharyngeal tonsil (adenoids) lies at the junction of the roof and posterior wall.

2. Posterior Wall

• Formed by the Arch of the atlas vertebra (C1).
• Covered by prevertebral muscles and fascia.
• Extends to the junction of the hard and soft palate.

3. Floor

• Anteriorly formed by the soft palate.
• Posteriorly deficient, forming the Nasopharyngeal Isthmus, which connects the nasopharynx to the oropharynx.

What are the boundaries of Nasopharyngeal Isthmus?

🔸 Passavant’s Ridge:

• A U-shaped mucosal ridge formed by fibers of the Palatopharyngeus muscle.

What is the importance of Passavant's ridge?

4. Anterior Wall

• Formed by the posterior nasal apertures (choanae).
• Structures projecting into the choanae:
  • Posterior ends of the inferior and middle conchae.
• Communication with the nasal cavity occurs here.

5. Lateral Wall

• Contains several important structures:

  • Pharyngeal opening of the Eustachian tube

What is the distance of the pharyngeal opening of Eustachian tube from the posterior end of Inferior Turbinate?

• Torus tubarius

  • Cartilaginous elevation around the Eustachian tube opening.
  • Site of the tubal tonsil (part of Waldeyer's ring).

• Fossa of Rosenmüller

  • Recess above and behind the torus tubarius.

What are the boundaries of Fossa of Rosenmuller?

Which tumor is commonly seen arising from Fossa of Rosenmuller?

• Salpingopharyngeal Fold
  • Mucosal fold covering the salpingopharyngeus muscle extending downward from the torus tubarius.

🏷️ Other Important Structures in the Nasopharynx

• Rathke's Pouch

  • Remnant structure seen as a dimple above the adenoids.

Which tumor arises from rathke's pouch?

• Nasopharyngeal Tonsil (Adenoids)

  • Subepithelial lymphoid tissue at the junction of roof and posterior wall.
  • Enlarges till about 6 years of age, then involutes.

• Nasopharyngeal Bursa

  • Median epithelial-lined recess within the adenoids.
  • May lead to persistent postnasal discharge or Thornwaldt's cyst if infected.

• Tubal Tonsils

  • Located at the torus tubarius.
  • Enlargement can obstruct the Eustachian tube, affecting middle ear ventilation.

🩸 Lymphatic Drainage of Nasopharynx

Drains into:

• Upper deep cervical lymph nodes (directly or via Retropharyngeal/ Parapharyngeal nodes)
• Spinal accessory chain of lymph nodes
• Can cross the midline to the contralateral lymph nodes

🧬 Epithelial Lining of the Nasopharynx

• Anteriorly: Lined by ciliated pseudostratified columnar epithelium (respiratory type).
• Posteriorly: Lined by non-keratinized stratified squamous epithelium.
• Transitional Zone: Area where these two types of epithelium meet.

🧠 Nerve Supply of Nasopharynx

• Pharyngeal branch of the Maxillary nerve (V2) via the pharyngotympanic (Eustachian) tube
• Pharyngeal branch of the Pterygopalatine ganglion, passing through the palatovaginal canal

🗣️ Functions of Nasopharynx

• Air Conduction
• Middle Ear Ventilation
• Closure during Swallowing
• Voice Resonance
• Mucus Drainage