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The frontonasal duct passes inferior-ward [5] to open either [3] into the middle nasal meatus at the anterior end of [3] the ethmoidal infundibulum, [3] [5] [2] or into the anterior ethmoidal air cells (which then in turn drain into the nasal cavity). [3] The duct is lined by mucous membrane. [citation needed]
The frontonasal duct may or may not drain into the ethmoidal infundibulum - this is determined by the place of attachment of the uncinate process of the ethmoid bone: if the uncinate process is attached to the lateral nasal wall, the frontonasal duct will open directly into the middle nasal meatus; if otherwise, it will drain into the infundibulum.
In anatomy, the term nasal meatus [1] can refer to any of the three meatuses (passages) through the skull ' s nasal cavity: the superior meatus (meatus nasi superior), middle meatus (meatus nasi medius), and inferior meatus (meatus nasi inferior). The nasal meatuses are the spaces beneath each of the corresponding nasal conchae.
The uncinate process can be attached to either the lateral nasal wall, on the lamina papyracea (50%), the anterior cranial fossa, on the ethmoidal roof (25%), or the middle concha (25%). The superior attachment of the uncinate process determines the drainage pattern of the frontal sinus.
A narrow opening called a sinus ostium from each of the paranasal sinuses allows drainage into the nasal cavity. The maxillary sinus is the largest of the sinuses and drains into the middle meatus. Most of the ostia open into the middle meatus and the anterior ethmoid, that together are termed the ostiomeatal complex. [32]
The middle ethmoidal cells drain directly into the middle nasal meatus. [3] The posterior ethmoidal cells drain directly into the superior nasal meatus [3] [5] at the sphenoethmoidal recess; [5] sometimes, one or more opens into the sphenoidal sinus. [4]
With the advent of nasal endoscopes, endoscopic dacryocystorhinostomy is becoming popular. In this procedure, a nasal endoscope is used to visualise the lacrimal sac through the nasal cavity. The bone covering the lacrimal sac is nibbled out. The medial wall of the sac is incised or excised, facilitating drainage of tears into the nasal cavity.
The lateral surface of the middle concha is concave, and assists in forming the middle meatus of the nose. The middle ethmoidal cells open into the central part of this meatus, and a sinuous passage, termed the infundibulum, extends upward and forward through the labyrinth and communicates with the anterior ethmoidal cells, and in about 50% of ...