The path of extra sound in the ear is

Options

A. scala vestibulu `to` scala media `to` scala tympani `to` fenestra ovalis `to` tympanic cavity `to` Eustachian tube `to` pharynx
B. scala vestibuli `to` helicotrema `to` scala media `to` fenestra rotunda `to` Eustchian tube `to` pharynx
C. scala vestibulu `to` helicotrema `to` scala lympani `to` fenestra rotunda `to` tympanic cavity `to` Eustachian tube `to` pharynx
D. scala vestibuli `to` helicotrema `to` fenestra fotunda `to` Eustachian tube `to` pharynx

Answer

### Step-by-Step Solution:

1. **Sound Entry**: The path of sound begins when sound waves enter the ear through the external ear, specifically the pinna (the outer part of the ear).

2. **Vibration of Ear Bones**: After entering, the sound waves travel through the ear canal and cause the eardrum to vibrate. These vibrations are then transmitted to three small bones in the middle ear known as the ossicles: the malleus (hammer), incus (anvil), and stapes (stirrup).

3. **Oval Window**: The stapes is connected to a membrane called the oval window. The vibrations from the stapes push against the oval window, transferring the sound waves into the inner ear.

4. **Scala Vestibuli**: Once the sound waves pass through the oval window, they enter a fluid-filled structure called the scala vestibuli, which is part of the cochlea in the inner ear.

5. **Helicotrema**: The sound waves then travel through the scala vestibuli until they reach a point called the helicotrema. This is a membrane that separates the scala vestibuli from the scala tympani.

6. **Scala Tympani**: After passing through the helicotrema, the sound waves enter the scala tympani, another fluid-filled chamber in the cochlea.

7. **Fenestra Rotunda**: The sound waves then travel to the fenestra rotunda (round window), which is another membrane that allows the waves to exit the cochlea and move into the middle ear.

8. **Eustachian Tube**: From the fenestra rotunda, the sound waves travel to the middle ear and then through the Eustachian tube, which connects the middle ear to the pharynx.

9. **Brain Processing**: Finally, the sound signals reach the brain, where they are interpreted and understood.

### Summary of the Path:
- **Pinna** → **Eardrum** → **Malleus** → **Incus** → **Stapes** → **Oval Window** → **Scala Vestibuli** → **Helicotrema** → **Scala Tympani** → **Fenestra Rotunda** → **Middle Ear** → **Eustachian Tube** → **Pharynx** → **Brain**.