The auditory tube (Eustachian tube) is a narrow, tube-like structure connecting the middle ear cavity to the upper part of the throat. This passageway allows air to move between the outside world and the enclosed space behind the eardrum, maintaining a healthy environment within the middle ear. This article focuses on the anatomical location of the opening closest to the throat, known as the distal or pharyngeal opening.
The Exact Location of the Distal Opening
The distal opening of the auditory tube is situated within the nasopharynx, the section of the throat located directly behind the nasal cavity. This opening, anatomically referred to as the pharyngeal orifice, is positioned on the lateral wall of the nasopharynx, slightly behind the posterior end of the inferior nasal concha. The structure itself is the cartilaginous, more flexible two-thirds of the tube’s total length.
The opening is identified by a prominent, lip-like rim of tissue surrounding it, called the torus tubarius. This is an elevation of the mucous membrane caused by the underlying cartilage of the tube. The actual opening lies anterior to this cartilaginous cushion. Immediately behind the torus tubarius is a small indentation in the nasopharyngeal wall known as the pharyngeal recess (fossa of Rosenmüller). This precise location allows the throat muscles to interact with the tube’s cartilage to regulate its function.
How the Auditory Tube Maintains Ear Health
The auditory tube performs two functions for the middle ear: pressure equalization and drainage. For most of the day, the tube remains collapsed and closed to protect the middle ear from unwanted sounds and secretions. It is designed to open briefly and actively, typically about 1,000 times per day, during actions such as swallowing, yawning, or chewing.
The active opening of the tube is primarily facilitated by the contraction of the tensor veli palatini muscle, which attaches to the tube’s cartilage. This muscle pulls the walls of the tube apart, allowing a temporary rush of air to enter or exit the middle ear cavity. This ventilation ensures the air pressure inside the middle ear remains equal to the surrounding atmospheric pressure, which is why swallowing during an airplane ascent or descent prevents that uncomfortable pressure sensation.
The second function, mucociliary clearance, involves the drainage of fluid or mucus that accumulates in the middle ear. The tube’s lining is covered with tiny, hair-like structures called cilia, which sweep debris toward the pharyngeal opening. The contraction of the tensor veli palatini muscle during opening also aids this process by compressing the tube and propelling the material toward the nasopharynx. The levator veli palatini muscle also contributes by elevating the soft palate and assisting the overall mechanism of tube opening.
When the Distal Opening Malfunctions
When the pharyngeal opening fails to operate correctly, it results in Eustachian Tube Dysfunction (ETD). The most common form of ETD occurs when the tube is obstructed or fails to open, often due to inflammation from a cold, allergies, or infection. This failure to ventilate the middle ear leads to a pressure imbalance, causing a feeling of fullness or blockage in the ear.
Other common symptoms of this blockage include muffled hearing, clicking or popping sounds, and sometimes pain or dizziness. In severe cases, the inability to equalize pressure during altitude changes can cause a painful condition called barotrauma. Conversely, Patulous Eustachian Tube (P-ET) occurs when the tube remains open inappropriately. This constant opening allows sounds from the nose and throat to travel up the tube, leading to symptoms like autophony (hearing one’s own voice or breathing sounds abnormally loudly).