The structure which opens in the nasopharynx that permits air pressure on both sides of tympanic membrane of the ear to be kept equal is :-

Options

A. Oval window
B. Tube of cochlea
C. Auditory nerve
D. Eustachian tube

Answer

To solve the question regarding the structure that opens in the nasopharynx and equalizes air pressure on both sides of the tympanic membrane, follow these steps:

### Step 1: Understand the Anatomy of the Ear
- The ear is divided into three main parts: the outer ear, middle ear, and inner ear.
- The tympanic membrane (eardrum) is located in the middle ear and separates it from the outer ear.

**Hint:** Remember the three parts of the ear and their functions.

### Step 2: Identify the Function of the Tympanic Membrane
- The tympanic membrane vibrates in response to sound waves.
- For it to function properly, the air pressure on both sides of the membrane must be equal.

**Hint:** Consider why equal pressure is important for sound transmission.

### Step 3: Locate the Structure that Equalizes Pressure
- The structure responsible for equalizing air pressure on both sides of the tympanic membrane is the Eustachian tube.
- The Eustachian tube connects the middle ear to the nasopharynx, allowing air to flow in and out, thus equalizing pressure.

**Hint:** Think about how the body maintains balance and pressure in different environments.

### Step 4: Confirm the Correct Answer
- Among the options provided, the Eustachian tube (also known as the auditory tube) is the correct answer.
- Other structures mentioned, such as the oval window, cochlea, and auditory nerve, do not serve this function.

**Hint:** Review the roles of the other structures to reinforce your understanding.

### Final Answer
The structure that opens in the nasopharynx and permits air pressure on both sides of the tympanic membrane to be kept equal is the **Eustachian tube**.

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