What produces striations in muscle fibers?

i know i chose health, but its the closest thing they have to human anatomy.

Striations (muscle texture) appear in a strong muscle with a very low % of body fat

Air goes past the epiglottis and into the trachea when you breathe in. from there, it goes to your vocal cords in the larynx until it reaches the bronchi. from the bronchi, air passes into each lung.