Frontal sinus

The frontal sinuses are the paranasal sinuses within the frontal bone. They are lined with mucosa and are most often two in number.

  • location: anterior frontal bones on either side of the midline behind the brow ridges
  • blood supply: supratrochlear, supraorbital and anterior ethmoidal arteries
  • innervation: supraorbital and supratrochlear nerves

The frontal sinus has two chambers, one on each side, and they are almost always asymmetrical. Each sinus extends superior to the medial end of the eyebrow and back into the orbital portion of the frontal bone. However, three or more chambers may be present in ~10% (range 1.5%-21%). It is divided by thin bony intrasinus septa, usually off-midline and rarely dehiscent.

The orbit and anterior cranial fossa form important relations to these sinuses. The sinus drains from an ostium in its lower medial corner into the anterior portion of the semilunar hiatus found in the middle meatus. This occurs via the ethmoidal infundibulum and/or the frontonasal duct.

The frontal sinus is supplied by the supratrochlear, anterior ethmoidal, and supraorbital arteries, all of which are branches of the ophthalmic artery. Venous drainage is via the superior ophthalmic veins.

Lymph drainage of the frontal sinus is into the submandibular nodes compared to the overlying skin which drains to the pre-auricular groups of nodes.

  • may be absent (i.e. aplasia) or underdeveloped (i.e. hypoplasia): unilateral (4%) or bilateral (5%)
  • may be large: extending through zygomatic processes, orbital bones, and into the squamae

They develop from anterosuperior pneumatisation of the frontal recess into the frontal bone. Development begins late in intrauterine life or may start after birth (from one to twenty years), initially in the vertical segment. Pneumatisation develops from one to twelve years-old.

Head and neck anatomy
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Article information

rID: 7037
System: Head & Neck
Section: Anatomy
Tags: refs, sinus
Synonyms or Alternate Spellings:
  • Frontal sinuses

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Cases and figures

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    Figure 1: in red on annotated CT
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    Case 1: normal sinuses on CT
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    Case 2: aplastic frontal sinues
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