Orbit is an innocent bystander that is
afflicted by lesions of the Paranasal Sinuses (PNS). Orbits share 3 walls with
the sinuses, frontal sinuses on the supero-medial aspects of the orbits,
ethmoid sinuses medially and maxillary sinuses inferiorly.
Between the ethmoids and the orbits, there is
lamina papyraecea which is a very thin bone. Between the maxillary sinus and
the floor of the orbit, the bone is weakened by the passage of the infraorbital
nerve. The periorbita
or the periosteum of the orbit is a tough structure that resists invasion
by tumors.
Once the tumor transgresses this robust layer,
it spreads to the orbital spaces easily due to lack of barriers that check
tumor spread. There is also rich vascular communication between the sinuses and
the orbit, which acts as a conduit for spread of infections and tumors. The
last but not the least is the communication between the nasal cavity and the
orbit through the Nasolacrimal Duct.
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