Nasogastric tube insertion is a blind procedure; i.e., the relevant anatomy is not visible to the operator during insertion. However, knowledge of the structural and functional anatomy of the nose and oropharynx is essential to the technique.
To the left, you will find a video presentation that clearly demonstrates the relevant anatomy. Below, you will find additional textual information that is equally important. We strongly recommend reviewing both resources to obtain a thorough understanding of the anatomy. |
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Entrance to the nasal cavity is obtained through the anterior nares. The nasal floor is comprised of the hard palate (including the maxilla and the palantine bone) and the soft palate. The nasal septum separates the right and left nasal cavities and contains both cartilage and bone (including the vomer and the perpendicular plate of the ethmoid bone.) The superior, middle, and inferior turbinates extend from the lateral walls of the nasal cavity; these structures are projections of the walls of the maxillary and ethmoid sinuses. 20 A properly inserted nasogastric tube will pass underneath the inferior turbinate. |
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 The roof of the nasal cavity is narrow and ends blindly. It is comprised of the frontonasal, ethmoid and sphenoid bones. 20 The cribriform plate (a portion of the ethmoid bone) is very thin and if fractured, may provide a misdirected NGT a portal of entry directly into the cranial cavity.
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The posterior nasal cavities converge into the choanae, which is the beginning of the pharynx. Behind the nasal cavities, this muscular passageway is called the nasopharynx, and becomes the oropharynx as it passes behind the oral cavity. At the level of the larynx, the trachea is found anterior to the esophagus. The epiglottis is a cartilagenous structure that lies directly anterior to the tracheal aperture. During swallowing, the larynx raises and the epiglottis bends posteriorly to cover the trachea, thus preventing aspiration of food into the lungs. 20 This physiology is taken advantage of during the insertion of a NGT. (See Procedure section for details.) The anatomy of the pharyngeal region is illustrated in the accompanying video presentation. |
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