Anatomy of the Sinuses Quiz

Nose & Paranasal Sinuses

• The nose and paranasal sinuses are studied together
• The presenter is Assoc. Prof. Dr. Azian Abd Latiff, from the Department of Anatomy, Medical Faculty, UKM.

External Nose

• Features:
  • Root: Attaches to the forehead
  • Dorsum: The upper part of the nose
  • Apex/Tip: The tip of the nose
  • Naris/Nostril: Bounded by ala and nasal septum
  • Nasal Septum: Separating the left and right nasal cavities
• Framework:
  • Composed of cartilaginous and bony parts
  • Lateral Cartilages
  • Septal Cartilages
  • Alar Cartilages
  • Nasal bones
  • Frontal processes of the maxillae
  • Nasal part of the frontal bone & its nasal spine
  • Bony nasal septum

Nasal Cavity

• Roof:
  • Middle part: formed by the cribriform plate of the ethmoid bone
  • Anterior part: nasal part of frontal bone, nasal bone & cartilages
  • Posterior part: inferior surface of body of sphenoid
• Lateral Wall:
  • Separates the nasal cavity from the orbit and maxillary sinus
  • Characterized features:
    • Vestibule (anterior): LIned by skin with vibrissae(hairs)
    • Posterior part: Choanae (internal nasal space)
    • 3 bony projections: conchae (turbinates)
• Floor: Formed by:
  • Palatine process of maxilla
  • Horizontal plate of palatine bone
• Medial Wall/Nasal Septum:
  • Divides the nasal cavity into 2 parts
  • Consists of:
    • Bony part: Vomer & perpendicular plate ethmoid
    • Cartilaginous part: Nasal spine of frontal bone, Nasal crest of nasal bone, Septal cartilage, Septal process of inferior nasal cartilage, Columella
• Nerve Supply:
  • Internal nasal branch of anterior ethmoidal nerve (branch of V1): anterosuperior part of nasal septum
  • Nasopalatine nerve (branch of V2): posteroinferior part of nasal septum
  • Olfactory nerves (15-20 bundles): provide smell sensation
• Blood Supply:
  • Key areas affected: Kiesselbach's plexus/Little's area (common site of epistaxis - nosebleed), maxillary sinus
  • Various arteries contribute: Sphenopalatine (maxillary), Anterior & Posterior ethmoidal (ophthalmic), Greater palatine (maxillary), Superior labial (facial), Lateral nasal branch (facial)

Paranasal Sinuses

• Air-filled extensions of the respiratory part of the nasal cavity into cranial bones
• Paired but asymmetrical
• Lined by respiratory epithelium
• Various functions: air-conditioning chambers, resonating chambers, lighter bones
• Bones involved: Frontal, Sphenoidal, Ethmoidal, Maxilla

Sphenoidal Sinus

• A septum separates the left and right sinus
• Located in the sphenoid bone (fragile)
• Superior relations: Optic chiasma, Pituitary gland
• Lateral relations: Internal carotid artery, Cavernous sinus
• Posterior: Pons and medulla oblongata
• Age 6: size of a small pea
• Blood supply: Posterior ethmoidal vessels

Ethmoidal Sinuses

• 3-18 small interconnected air spaces
• 3 groups: anterior, middle, posterior
• Lateral relations: Orbital plate of ethmoid
• Blood supply: Anterior and posterior ethmoidal branches of ophthalmic artery

Frontal Sinuses

• Two in number
• Extends: upward and above the medial end of the eyebrow, backward into the medial part of the roof of the orbit
• Blood supply: supra-orbital vessels
• Nerve supply: supra-orbital nerves

Maxillary Sinuses

• Largest and first to be formed
• Pyramidal shaped
• Roof: orbital surface of maxilla (traversed by infra-orbital nerve and vessel)
• Floor: alveolar process of maxilla (closely related to roots of premolar and molar teeth)
• Posterior wall: anterior wall of infratemporal fossa (pierced by posterior superior alveolar vessels and nerves)
• Blood supply: anterior, middle and posterior superior alveolar vessels of maxillary artery
• Nerve supply: similar to superior alveolar nerves

Openings of the Paranasal Sinuses

• Meatus: space beneath the concha
  • Inferior meatus: largest, beneath the inferior concha and opening of the nasolacrimal duct.
  • Middle meatus: beneath the middle concha and receives openings from maxillary sinus, anterior & middle ethmoidal sinus, frontal sinus. Special features: uncinated process, ethmoid bulla, semilunar hiatus.
  • Superior meatus: shortest, beneath the superior concha and opening of posterior ethmoidal sinus
  • Sphenoethmoidal recess: above the superior concha and opening of sphenoidal sinus

Applied Anatomy

• Maxillary sinusitis: inflammation of the maxillary sinus, often caused by a virus
• Sinusitis: detected by radiological examination
• Endoscopic sinus surgery: procedure to remove blockages, often including the uncinate process
• Oroantral fistula: a defect in the maxillary sinus floor, often indicated by opacification on CT scans