The third stirrup-shaped bone in the ear that transmits vibrations and connects the incus to the oval window is the?

• A. Stapes
• B. Incus
• C. Malleus
• D. Pinna

Answer: (A)

Sound transmission through the middle ear relies on a chain of three tiny bones designed to move vibrations efficiently from the eardrum into the inner ear. The last bone in that chain is the stirrup-shaped one, whose footplate fits into the oval window of the cochlea. When the eardrum vibrates, the hammer (the first bone) moves, passing the motion to the anvil, and then to this final bone. The stapes pushes on the oval window, generating waves in the inner-ear fluid that kick off the hearing process. The outer ear structure called the pinna isn’t a middle-ear bone and doesn’t transmit these vibrations, while the hammer and anvil are earlier links in the chain.