His opinion is very important.

I strained a muscle at the gym yesterday.

He broke his leg bone.

In Sanskrit phonology, retroflex sounds play an important role.

A back vowel is a sound where the back of the tongue approaches the palate.

Back vowels are vowels that are pronounced using the back of the tongue.

Retroflex sounds are difficult to pronounce.

A coronal is a sound that is pronounced using the tip or the upper part of the tongue.

Retroflex is a phonetic feature that does not exist in Japanese.

A dorsal sound is a sound that is pronounced by the back of the tongue approaching or touching the palate or pharynx.