Sphenoid sinus

The sphenoid sinus is the most posterior paranasal sinus.

The sphenoid sinuses are paired spaces formed within the body of the sphenoid bone, communicating with the roof of the nasal cavity via the sphenoethmoidal recess in its anterior wall. The two sinuses are separated by a septum which may or may not be in the midline. It usually lies anteroinferior to the sella.

A large sinus can show a number of ridges and depressions related to closely adjacent structures. These can include the pituitary gland, optic nerve and internal carotid artery.

  • conchal
  • lateral recess
  • presellar
  • sellar (which can be incomplete or complete)

Lymph drainage occurs via afferent vessels leading into the retropharyngeal nodes

With respect to optic nerve relationship:

  • type 1: adjacent to sphenoid sinus
  • type 2: indenting the sinus
  • type 3: traversing the sinus
  • type 4: adjacent to posterior ethmoid sinus

Pneumatisation starts at around 2 years of age and it develops more slowly than the other paranasal sinuses.

It is important to look for and report the type of pneumatisation of this sinus and to report the relationship with adjacent neurovascular structures, especially dehiscence.

Head and neck anatomy
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Article information

rID: 24668
System: Head & Neck
Section: Anatomy
Synonyms or Alternate Spellings:
  • Sphenoid sinuses
  • Sphenoidal sinus
  • Sphenoidal sinuses

Cases and figures

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    Figure 1: in green on annotated CT
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    Case 1: sphenoid sinus aplasia
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