Question

external acoustic meatus
ear drum
tympanic membrane
external eustachian tube

Explanation:

Identify the highlighted structure

Using the Middle Ear Anatomy knowledge point
The provided anatomical diagram shows a cross-section of the human ear. The structure highlighted in bright green is the canal leading from the outside of the ear (auricle/pinna) to the tympanic membrane (eardrum). This canal is anatomically known as the external acoustic meatus (or external auditory canal).

Evaluate the given options

• external acoustic meatus: This is the correct anatomical term for the highlighted green canal.
• ear drum / tympanic membrane: These refer to the thin membrane at the end of the canal (shown in pinkish-purple at the medial end of the green highlighted tube), not the canal itself.
• external eustachian tube: This is anatomically incorrect; the eustachian tube connects the middle ear to the nasopharynx, not the external environment.

Answer:

• external acoustic meatus (Correct answer)
• ear drum
• tympanic membrane
• external eustachian tube