Valsalva and Eustachian tube

[Kiv]

I hope that this will not be answered using AI.

The starting premise is established as a certainty here:During the Valsalva maneuver, gas indeed moved through the Eustachian tube (ET) into the middle ear, and the middle ear pressure increased as a result of this gas transfer.

The question is solely this:Does it follow as a practical certainty that, at least in one single “frozen” moment during the Valsalva, there existed an uninterrupted gas-phase route / continuous gas cavity / air column from the pharynx to the middle ear, even if it were extremely narrow and short-lived?

Important Constraints:

• Do not address whether “air usually moves,” as that is already established as the premise.
• Do not address whether the ET was continuously open throughout the Valsalva; the question concerns only at least one single moment (a moment where time is frozen).
• Do not evade the question by stating that real-time imaging does not exist for every case; specifically evaluate what follows logically from the given premise.
• Do not pivot to swallowing, unless it is used only as a weak alternative model.
• Specifically evaluate the Valsalva maneuver, characterized by active overpressure in the nasopharynx, rather than the muscle-driven opening seen in swallowing.
• Take into account that McDonald’s cine-CT bolus/progressive opening model was based on a small, primarily swallow-oriented, and hypothetical dataset.
• Take into account that subsequent literature on the Valsalva maneuver leans toward the view that once the opening threshold is exceeded, a “continued column of air” is formed in the ET and that “most evidence suggests” the ET opens momentarily along its entire length.
• The question is not whether this is an absolute mathematical theorem in all possible biological worlds, but whether, given the premise, this is effectively the only credible explanation.

Please answer exactly this:Given the premise (i.e., that gas actually entered the middle ear via the ET during Valsalva), is it a practically certain conclusion that at least in one single moment, there was an uninterrupted pharynx–middle ear gas connection?

 

[weirdoguy]

I hope that this will not be answered using AI.

It is forbidden here on PF, so it won't. But I have no idea about what you wrote, so that's all I can say

 

[berkeman]

@Kiv -- is this question for schoolwork? What is the motivation for the question?

 

[Baluncore]

The question is solely this:Does it follow as a practical certainty that, at least in one single “frozen” moment during the Valsalva, there existed an uninterrupted gas-phase route / continuous gas cavity / air column from the pharynx to the middle ear, even if it were extremely narrow and short-lived?

No.
In some cases, when the ET contains a fluid, the fluid can move sufficiently to equilibrate pressure, without completely emptying the ET of the fluid. It comes down to a compression ratio; the volume of the inner ear, the volume of the ET, and the pressure difference.

 

[Kiv]

@Kiv -- is this question for schoolwork? What is the motivation for the question?

Not for school, for personal use

 

[berkeman]

Not for school, for personal use

Okay, fair enough. I've moved your thread from the Classical Physics forum to the Biology/Medical forum where it fits better.

The starting premise is established as a certainty here:During the Valsalva maneuver, gas indeed moved through the Eustachian tube (ET) into the middle ear, and the middle ear pressure increased as a result of this gas transfer.

Can you give a scientific/medical reference for this premise? Thanks.

 

[Kiv]

No.
In some cases, when the ET contains a fluid, the fluid can move sufficiently to equilibrate pressure, without completely emptying the ET of the fluid. It comes down to a compression ratio; the volume of the inner ear, the volume of the ET, and the pressure difference.

Thanks you for the perspective. However, I believe this model addresses a different scenario and bypasses the strict premise of the thought experiment.

First, a minor anatomical correction: the Eustachian tube connects to the middle ear (a gas-filled cavity), not the inner ear.

More importantly, the scenario you described is essentially a 'fluid piston' effect. In your model, a fluid plug moves up the tube, compressing the existing air in the cavity to equalize pressure without the plug clearing the tube. While perfectly valid in fluid mechanics for transferring pressure, it violates the core premise of my question: gas itself successfully transferred from Side A (nasopharynx) to Side B (middle ear).

If we strictly enforce the given premise that the physical medium that entered the middle ear was gas, not a shifting liquid plug—does the conclusion hold? Is it physically possible for gas to travel from Side A to Side B via static overpressure without a continuous gas-phase lumen existing at some moment?"

 

[Kiv]

Okay, fair enough. I've moved your thread from the Classical Physics forum to the Biology/Medical forum where it fits better.


Can you give a scientific/medical reference for this premise? Thanks.

The premise is based on the standard physiological understanding of Eustachian tube ventilation. For example, McDonald et al. (2012), "New insights into mechanism of Eustachian tube ventilation based on cine computed tomography images", discusses how air traverses the ET to maintain middle ear pressure.

However, for the purpose of my question, I am asking you to accept this as a given premise (a thought experiment). I am not asking if it happens, but how the fluid dynamics must work if we observe that gas has indeed moved from the nasopharynx to the middle ear.

My goal is to understand the physical requirement of a continuous lumen in this specific successful scenario.

 

[Kiv]

Okay, fair enough. I've moved your thread from the Classical Physics forum to the Biology/Medical forum where it fits better.

I understand the biological context, but this is fundamentally a question of fluid dynamics and topology. I am not asking for clinical advice or biological functions, but rather the physical requirement for gas-phase continuity in a high-resistance flexible conduit. The biological terms are just the specific application of the model.

 

[pinball1970]

The starting premise is established as a certainty here:During the Valsalva maneuver, gas indeed moved through the Eustachian tube (ET) into the middle ear, and the middle ear pressure increased as a result of this gas transfer

Can you state where this comes from? The frame work of your question looks like Ai

 

[Baluncore]

First, a minor anatomical correction: the Eustachian tube connects to the middle ear (a gas-filled cavity), not the inner ear.

Sorry, I was asleep when I replied.

While perfectly valid in fluid mechanics for transferring pressure, it violates the core premise of my question: gas itself successfully transferred from Side A (nasopharynx) to Side B (middle ear).

Is it physically possible for gas to travel from Side A to Side B via static overpressure without a continuous gas-phase lumen existing at some moment?"

Yes, gas can travel from side A to side B, as bubbles, between multiple fluid pistons, without there being a continuous air path between the sides A and B. That could occur when the fluid entering the ET contained bubble envelopes, that created fluid pistons in the ET, as they were introduced.

Maybe you need to move, or reestablish, the goal posts, to preclude that possibly unwelcome scenario.

The way this question is worded, makes me feel like I am wearing a straitjacket, in an insane asylum.