Space

Frontal sinus

Variable air spaces above the medial orbits

Head & neckRespiratory system

High-yield

Frontal drainage reaches the middle meatus, sometimes through the ethmoidal infundibulum and sometimes directly. Describing every route as a frontonasal duct entering the hiatus semilunaris misses this variation.

Overview

The frontal sinuses develop within the frontal bone and are often unequal on the two sides. They enlarge through childhood, and one or both can remain small or absent. Mucus exits through an inferior opening and a variable drainage pathway leading to the middle meatus.

Reference facts

Boundaries: Within the frontal bone between anterior and posterior walls; the floor overlies the orbit and the posterior wall borders the anterior cranial fossa.
Contents: Air and a mucus-producing respiratory lining with cilia that move secretions toward the opening.
Communications: Frontal ostium and frontal drainage pathway to the middle meatus, with the uncinate attachment influencing whether the infundibulum is included.
Blood supply: Supraorbital and anterior ethmoidal arterial branches.
Innervation: General sensation through the supraorbital nerve, CN V1; autonomic fibers accompany regional nerves and vessels.

Clinical correlation

Frontal sinus infection can extend to adjacent bone or intracranial tissues. Pott's puffy tumor is a forehead subperiosteal abscess associated with frontal osteomyelitis, not a neoplasm. Intracranial spread can occur through bone or venous connections.

Frequently asked questions

What are the boundaries of the frontal sinus?

Within the frontal bone between anterior and posterior walls; the floor overlies the orbit and the posterior wall borders the anterior cranial fossa.

What does the frontal sinus contain?

The frontal sinus contains the air and a mucus-producing respiratory lining with cilia that move secretions toward the opening.

What does the frontal sinus communicate with?

Frontal ostium and frontal drainage pathway to the middle meatus, with the uncinate attachment influencing whether the infundibulum is included.