Detailed Notes on Nasal Anatomy and Disorders

Anatomy of the Nose and Paranasal Sinuses

Structure of the Nasal Pyramid

  • The nose is shaped like a pyramid.
  • Apex or Nasal Lobule: The pointed tip of the nose.
  • Dorsum Nasi: The posterior-superior extension from the apex.
Key Features
  • Nasion: The junction between nasal bones and frontonasal suture.
  • Glabella: A flattened area slightly raised between the two supraorbital arches.

Skeletal Structure

  • Bony Structures:
  • Nasal bones,
  • Ascending processes of the maxillae.
  • Fibrocartilaginous Structures:
  • Alar cartilages,
  • Triangular cartilages.

Anatomy of Nasal Structures

  • Columella: The membranous extension from the apex to the center of the upper lip.
  • Anterior narinas or nostrils are bordered by lower lateral cartilages and the floor of the nose.
Lateral Nasal Cartilages
  • Lateral Alar Cartilages: Support the nose and maintain narinas' structure.
  • They contribute significantly to the airway's resistance, especially at the limen nasi area.

Nasal Septum

  • Divides the nasal cavity into two nostrils.
  • Formed by:
    • Perpendicular plate of the ethmoid bone (superior),
    • Septal cartilage (anterior),
    • Vomer bone (inferior).

Nasal Cavities

  • Two cavities formed by the palatine processes of maxillas and horizontal plates of palatine bones.
  • Nasal meatuses are formed by the turbinates (inferior, middle, and superior).

Functions of the Nose

  • Olfactory Function: Critical for enhancing food flavor and stimulating appetite.
  • Respiratory Function:
  • Normal airflow rates:
    • At REST: 6 L/min,
    • During maximum ventilation: 50-70 L/min.
  • Modifications during inspiration include warming, humidifying, and purifying the air.
Air Conditioning Properties
  • Warming: Blood vessels in the nasal cavity keep air at ~31–34 °C regardless of external conditions.
  • Humidification: Mucous layer supports moisture retention leading to humid air entering the lungs.
  • Purification: Removal of particles heavier than 5 microns is 85-90% effective in the nasal cavity.

Paranasal Sinuses

  • Types:
  • Frontal,
  • Maxillary,
  • Ethmoid (anterior and posterior),
  • Sphenoidal sinuses.
  • Each sinus has ostia that drain to the nasal cavity.

Sinusitis and Blockages

  • Obstruction leads to sinusitis, forming a vicious cycle of obstruction, inflammation, and altered mucus production.

Surgical and Common Pathologies

  • Nasal Obstruction Syndrome: Can lead to symptoms like nasal breathing difficulty, hyposmia, and nasal voice.
  • Obstructions: Can occur due to adenoid hypertrophy, nasal trauma, or foreign bodies.

Epistaxis (Nosebleeds)

  • Management includes stabilizing the airway, controlling bleeding, and careful inspection of nasal structures.
  • Anterior Epistaxis: Common, often from the Kiesselbach's area.
  • Posterior Epistaxis: Often severe, may require surgical intervention.

Nasal Trauma and Fracture Management

  • Major Facial Injuries: Often lead to fractures of nasal bones requiring proper evaluation and management.
  • Nasal Fractures: Commonly associated with cosmetic deformities, characterized by bleeding, swelling, and obstruction.

Anomalies and Congenital Conditions

  • Choanal Atresia: Congenital blockage of the posterior nasal opening; may require surgical intervention.
  • Tumors: Such as gliomas or dermoid cysts, may have congenital origins, needing specific surgical approaches for treatment.