Ear Bones

INCUS

The incus or anvil is the anvil-shaped small bone or ossicle in the middle ear. Incus means "anvil" in Latin. It connects the malleus to the stapes. It was first described by Alessandro Achillini of Bologna. The incus transmits sound vibrations from the malleus to the stapes. The incus only exists in mammals, and is derived from a reptilian upper jaw bone, the quadrate bone. Embryologically it is derived from the first pharyngeal arch along with the rest of the bones of mastication, such as the maxilla and mandible.

MALLEUS

The malleus or hammer is a hammer-shaped small bone or ossicle of the middle ear which connects with the incus and is attached to the inner surface of the eardrum. The word is Latin for hammer. It transmits the sound vibrations from the eardrum to the incus.

STAPES

The stapes is the stirrup-shaped small bone or ossicle in the middle ear which is attached through the incudostapedial joint to the incus laterally and to the fenestra ovalis, the "oval window", medially. Stapes means stirrup in Latin. The oval window is adjacent to the vestibule of the inner ear. The stapes is the smallest and lightest bone in the human body. It was described by the professor Giovanni Filippo Ingrassia in 1546 at the University of Naples. The stapes transmits the sound vibrations from the incus to the membrane of the inner ear inside the fenestra ovalis. The stapes is also stabilized by the stapedius muscle, which is innervated by the facial nerve.[2]