Estapedio

Estapedio refers to the stapes, one of the three auditory ossicles of the middle ear. Also known as the stirrup bone, the estapedio is the smallest bone in the human body and forms part of the chain that transmits sound from the eardrum to the inner ear. Along with the malleus (hammer) and incus (anvil), the stapes connects with the incus at the incudostapedial joint and with the oval window by its footplate, which fits into the opening of the inner ear.

Anatomically, the estapedio is a slender, curved bone with a head that articulates with the incus, a neck, and a footplate that seals the oval window. It moves in small, precise motions as the tympanic membrane vibrates in response to sound. This movement, together with the other ossicles, provides impedance matching, amplifying and transferring sound energy from air to the fluid-filled cochlea.

The stapedius muscle, whose tendon attaches to the neck of the stapes, along with the facial nerve, mediates the acoustic reflex. In response to loud sounds, the stapedius contracts, reducing the amplitude of stapes motion to protect the inner ear from damage.

Developmentally, the stapes arises from neural crest cells, specifically from Reichert’s cartilage of the second pharyngeal arch. Clinically significant conditions include otosclerosis, in which the footplate becomes immobilized, causing conductive hearing loss; treatment options include stapedotomy or stapedectomy with a prosthetic implant.

The term estapedio is used in medical contexts to describe aspects related to the stapes.