The ''incus'' (: incudes) or anvil in the ear is one of three small

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...

s (

ossicles 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 ''ossi ...

) in the

middle ear The middle ear is the portion of the ear medial to the eardrum, and distal to the oval window of the cochlea (of the inner ear). The mammalian middle ear contains three ossicles (malleus, incus, and stapes), which transfer the vibrations ...

. 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 An anvil is a metalworking tool consisting of a large block of metal (usually Forging, forged or Steel casting, cast steel), with a flattened top surface, upon which another object is struck (or "worked"). Anvils are massive because the hi ...

().

Structure

The incus is the second of three

, very small bones in the

which act to transmit sound. It is shaped like an

, and has a long and short crus extending from the body, which articulates with the malleus. The short crus attaches to the posterior ligament of the incus. The long crus articulates with the stapes at the lenticular process. The superior ligament of the incus attaches at the body of the incus to the roof of the

tympanic cavity The tympanic cavity is a small cavity surrounding the bones of the middle ear. Within it sit the ossicles, three small bones that transmit vibrations used in the detection of sound. Structure On its lateral surface, it abuts the external audit ...

. The incus is homologous to the quadrate bone found in other tetrapods.

Function

Vibrations in the

are received via the tympanic membrane. The malleus, resting on the membrane, conveys vibrations to the incus. This in turn conveys vibrations to the stapes.

History

"Incus" means "anvil" in Latin. Several sources attribute the discovery of the incus to the anatomist and philosopher Alessandro Achillini. The first brief written description of the ''incus'' was by Berengario da Carpi in his ''Commentaria super anatomia Mundini'' (1521).

Andreas Vesalius Andries van Wezel (31 December 1514 – 15 October 1564), latinized as Andreas Vesalius (), was an anatomist and physician who wrote '' De Humani Corporis Fabrica Libri Septem'' (''On the fabric of the human body'' ''in seven books''), which is ...

, in his '' De humani corporis fabrica'', was the first to compare the second element of the ossicles to an anvil, thereby giving it the name ''incus''. The final part of the long limb was once described as a "fourth ossicle" by Pieter Paaw in 1615.

Additional images

File:Illu auditory ossicles-en.svg, Ossicles File:Occipital bone dissection.jpg, Tympanic cavity. Facial canal. Internal carotid artery. File:Slide1ghe.JPG, Auditory ossicles. Tympanic cavity. Deep dissection. File:Slide2ghe2.JPG, Aditory ossicles. Incus and malleus. Deep dissection.

References

External links

The Anatomy Wiz
''Incus'' {{Authority control Bones of the head and neck Auditory system Ear Ossicles Otorhinolaryngology Otology Middle ear