Final answer:
The tympanic membrane connects the external ear to the middle ear, which contains the ossicles: malleus, incus, stapes. The inner ear is connected to the middle ear by the stapes at the oval window. Loud sounds are moderated by the stapedius muscle, controlled by the facial nerve.
Step-by-step explanation:
The structure that connects the external ear to the middle ear is the tympanic membrane, commonly known as the eardrum. The middle ear contains three bones called the ossicles, which are in the order of the malleus (hammer), incus (anvil), and stapes (stirrup). These ossicles connect the eardrum to the oval window of the inner ear. The stapes, being the last of the ossicles, is directly connected to the inner ear, which consists of the cochlea and vestibule responsible for audition and equilibrium, respectively. The muscle that dampens loud sounds is the stapedius muscle, and it is controlled by the facial nerve, which is the seventh cranial nerve.