1. NOSE, PARANASAL SINUSES & NASOPHARYNX

Learning Outcomes

• At the end of this session, students must be able to:

  • List the functions of the nose.

  • Describe the anatomy of the nose and its associated structures.

  • Explain the structure and function of the paranasal sinuses.

  • Discuss the nasopharynx and its clinical relevance.

  • Identify important relations between the paranasal sinuses and surrounding structures.

  • Explain key clinical conditions related to the nose, paranasal sinuses, and nasopharynx.

The Nose

Functions

• Respiratory Passage: Facilitates airflow to the lungs.

• Organ of Smell: Houses olfactory receptors that detect odors.

Structure

• External Nose Components:

  • Frontal Bone: Forms the upper framework.

  • Nasal Bone: Provides structure and shape.

  • Cartilage: Forms the flexible portions, including the nostrils (nares).

  • Ala of Nose: The outer border of each nostril.

  • Philtrum: The groove between the nose and upper lip.

• Divisions:

  • External Nose: The visible part of the nose.

  • Nasal Cavity: Internal space involved in breathing and smell.

Anatomy Features

• Nasal Cavity:

  • Extends from the external nares (nostrils) to the choanae (posterior nasal apertures).

  • Divided by the nasal septum.

  • Subdivided into:

    • Roof: Approximately 7 cm long, 2 mm wide.

    • Floor: Comprised of the palatine process of the maxilla and the horizontal plate of the palatine bone.

Paranasal Sinuses

Overview

• Air-filled spaces located within certain bones surrounding the nasal cavity.

• Include:

  • Frontal Sinuses: Located above the eyes.

  • Maxillary Sinuses: Located in the maxilla.

  • Sphenoid Sinuses: Located in the sphenoid bone.

  • Ethmoidal Cells: Small air cells between the nasal cavity and the orbits.

Functions

• Contribute to lighter resonance in the voice.

• Help with humidifying and heating the air we breathe.

Nasopharynx

Structure

• Fibromuscular chamber approximately 15 cm long.

• Positioned behind the nose and above the soft palate.

• Communicates anteriorly with the nasal cavity via choanae and inferiorly with oropharynx via the pharyngeal isthmus.

Clinical Correlations

• Common conditions affecting the nasal area include:

  • Rhinitis: Inflammation of the nasal mucosa.

  • Epistaxis: Nosebleeds due to various causes (e.g., trauma, dry air).

  • Sinusitis: Inflammation of sinus cavities leading to congestion and pain.

  • Adenoids: Enlargement of the nasal pharyngeal lymphoid tissue that can obstruct airflow.

  • Spread of Cancer: Potential risk due to proximity of sinuses to nasal structures.

Important Structures and Relationships

• Eustachian Tube: Links the nasopharynx to the middle ear; involved in ear pressure regulation.

• Tonsils: Pharyngeal and palatine tonsils located in the oropharynx and contribute to immune response.