It is bounded inferiorly and anteriorly by the sharp concave margin of the uncinate process of the ethmoid bone, superiorly by the ethmoidal bulla, and posteriorly by the inferior nasal concha.
22.
The branches it gives rise to are called the internal and external nasal branches of the anterior ethmoidal nerve, and the external branch ultimately innervates skin on the lateral sides of the nose.
23.
The bulla ethmoidalis is caused by the bulging of the middle ethmoidal cells which open on or immediately above it, and the size of the bulla varies with that of its contained cells.
24.
The optic canal contains the optic nerve ( cranial nerve II ) and the ophthalmic artery, and sits at the junction of the sphenoid sinus with the anterior and posterior ethmoidal foramen and zygomatic orbital foramen.
25.
The mucous membrane in this sinus is innervated by the supraorbital nerve, which carries the postganglionic parasympathetic nerve fibers for mucous secretion from the ophthalmic nerve and supplied by the supraorbital artery and anterior ethmoidal artery.
26.
In case of fronto-ethmoidal epidermoid cysts, surgical resection appears to be the mainstay of treatment; however, the extent of resection is dictated by adherence of the tumor capsule to the surrounding vital structures.
27.
The anterior ethmoidal nerve then continues into the cranial cavity at the side of the cribiform plate of the ethmoid bone, sends sensory fibers to the meninges, and then enters the nasal cavity via the nasal slit.
28.
The "'hiatus semilunaris "'( or "'semilunar hiatus "') is a crescent-shaped groove in the lateral wall of the nasal cavity just inferior to the ethmoidal bulla.
29.
It consists of a thin infundibulum, extends upward and forward through the labyrinth and communicates with the anterior ethmoidal cells, and in about 50 % of skulls is continued upward as the frontonasal duct into the frontal sinus.
30.
The surgical procedures include the operation of diseased ethmoid compartments ( usually ethmoidal bulla ), widening of stenotic clefts ( uncinate process ) and freeing of prechambers ( agar nasi cells ) to the frontal and maxillary sinuses from disease.
