Paranasal Sinuses

Paranasal Sinuses

• Consist of the ethmoidal, frontal, maxillary, and sphenoidal sinuses.
• Are involved in a reduction of weight and resonance for voice.

A. Ethmoidal sinus

• Consists of numerous ethmoidal air cells , which are numerous small cavities within the ethmoidal labyrinth between the orbit and the nasal cavity.
• Its infection may erode through the thin orbital plate of the orbit.
• Can be subdivided into the following groups:
• Posterior ethmoidal air cells , which drain into the superior nasal meatus.
• Middle ethmoidal air cells , which drain into the summit of the ethmoidal bulla of the middle nasal meatus.
• Anterior ethmoidal air cells , which drain into the anterior aspect of the hiatus semilunaris in the middle nasal meatus.
  

B. Frontal sinus

• Lies in the frontal bone and opens into the hiatus semilunaris of the middle nasal meatus by way of the frontonasal duct (or infundibulum).
• Is innervated by the supraorbital branch of the ophthalmic nerve.

C. Maxillary sinus

• Is the largest of the paranasal air sinuses and is the only paranasal sinus that may be present at birth.
• Lies in the maxilla on each side, lateral to the lateral wall of the nasal cavity and inferior to the floor of the orbit, and drains into the posterior aspect of the hiatus semilunaris in the middle nasal meatus.

D. Sphenoidal sinus

• Is contained within the body of the sphenoid bone.
• Opens into the sphenoethmoidal recess of the nasal cavity.
• Is innervated by branches from the maxillary nerve and by the posterior ethmoidal branch of the nasociliary nerve.
• The pituitary gland lies above this sinus and can be reached by the transsphenoidal approach , which follows the nasal septum through the body of the sphenoid. Care must be taken not to damage the cavernous sinus and the internal carotid artery.

◄.....Go back to the Gross Anatomy homepage