Stapes in the context of "Ossicle"

The evolution of mammalian auditory ossicles was an evolutionary process that resulted in the formation of the mammalian middle ear, where the three middle ear bones or ossicles, namely the incus, malleus and stapes (a.k.a. "the anvil, hammer, and stirrup"), are a defining characteristic of mammals. The event is well-documented and important academically as a demonstration of transitional forms and exaptation, the re-purposing of existing structures during evolution.

The ossicles evolved from skull bones present in most tetrapods, including amphibians, sauropsids (which include extant reptiles and birds) and early synapsids (which include ancestors of mammals). The reptilian quadrate, articular and columella bones are homologs of the mammalian incus, malleus and stapes, respectively. In reptiles (and early synapsids by association), the eardrum is connected to the inner ear via a single bone, the columella, while the upper and lower jaws contain several bones not found in modern mammals. Over the course of mammalian evolution, one bone from the upper jaw (the quadrate) and one from the lower jaw (the articular) lost their function in the jaw articulation and migrated to form the middle ear. The shortened columella connected to these bones to form a kinematic chain of three ossicles, which serve to amplify air-sourced fine vibrations transmitted from the eardrum and facilitate more acute hearing in terrestrial environments.

Hyperacusis is an increased sensitivity to sound and a low tolerance for environmental noise. Definitions of hyperacusis can vary significantly; it often revolves around damage to or dysfunction of the stapes bone, stapedius muscle or tensor tympani. It is often categorized into four subtypes: loudness, pain (also called noxacusis), annoyance, and fear. It can be a highly debilitating hearing disorder.

There are a variety of causes and risk factors, with the most common being exposure to loud noise. It is often coincident with tinnitus. Proposed mechanisms in the literature involve dysfunction in the brain, inner ear, or middle ear.

The ossicles (also called auditory ossicles) are three irregular bones in the middle ear of humans and other mammals, and are among the smallest bones in the human body. Although the term "ossicle" literally means "tiny bone" (from Latin ossiculum) and may refer to any small bone throughout the body, it typically refers specifically to the malleus, incus and stapes ("hammer, anvil, and stirrup") of the middle ear.

The auditory ossicles serve as a kinematic chain to transmit and amplify (intensify) sound vibrations collected from the air by the ear drum to the fluid-filled labyrinth (cochlea). The absence or pathology of the auditory ossicles would constitute a moderate-to-severe conductive hearing loss.

The incus (pl.: incudes) or anvil in the ear is one of three small bones (ossicles) in the middle ear. The incus receives vibrations from the malleus, to which it is connected laterally, and transmits these to the stapes medially. The incus is named for its resemblance to an anvil (Latin: incus).

In the auditory system, the columella contributes to hearing in amphibians, reptiles and birds. The columella form thin, bony structures in the interior of the skull and serve the purpose of transmitting sounds from the eardrum. It is an evolutionary homolog of the stapes, one of the auditory ossicles in mammals.

In many species, the extracolumella is a cartilaginous structure that grows in association with the columella. During development, the columella is derived from the dorsal end of the hyoid arch.