The ''incus'' (plural incudes) or anvil is a

bone A bone is a Stiffness, rigid Organ (biology), organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red blood cell, red and white blood cells, store minerals, provid ...

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, which transfer the vibrations of the eardrum into waves in the ...

. The

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

-shaped small bone is one of three

ossicles The ossicles (also called auditory ossicles) are three bones in either middle ear that are among the smallest bones in the human body. They serve to transmit sounds from the air to the fluid-filled labyrinth (cochlea). The absence of the auditory ...

in the middle ear. The ''incus'' receives vibrations from the ''

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

'', to which it is connected laterally, and transmits these to the ''

stapes The ''stapes'' or stirrup is a bone in the middle ear of humans and other animals which is involved in the conduction of sound vibrations to the inner ear. This bone is connected to the oval window by its annular ligament, which allows the foo ...

'' medially. The ''incus'' is so-called because of its resemblance to an anvil ( la, Incus).

Structure

The incus is the second of the

, three 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

. The short crus attaches to the

posterior ligament of the incus The posterior ligament of the incus is a fibrous band that connects the tip of the short crus of the incus to the fossa incudis, running to the mastoid (posterior wall of the middle ear chamber). The posterior incudal ligament plays an important ...

. The long crus articulates with the

stirrup A stirrup is a light frame or ring that holds the foot of a rider, attached to the saddle by a strap, often called a ''stirrup leather''. Stirrups are usually paired and are used to aid in mounting and as a support while using a riding animal ( ...

at the lenticular process. The

superior ligament of the incus The superior ligament of the incus is a fibrous band that crosses from the body of the incus to the roof of the tympanic cavity just posterior to the superior ligament of the malleus The malleus, or hammer, is a hammer-shaped small bone or oss ...

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 auditory ...

Function

Vibrations in the

are received via the

tympanic membrane In the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear from the middle ear. Its function is to transmit sound from the air ...

. The malleus, resting on the membrane, conveys vibrations to the incus. This in turn conveys vibrations to the

History

"Incus" means "anvil" in Latin. Several sources attribute the discovery of the incus to the anatomist and philosopher

Alessandro Achillini Alessandro Achillini (''Latin'' Alexander Achillinus; 20 or 29 October 1463 (or possibly 1461)2 August 1512) was an Italian philosopher and physician. He is known for the anatomic studies that he was able to publish, made possible by a 13th-cent ...

. The first brief written description of the ''incus'' was by

Berengario da Carpi Jacopo Berengario da Carpi (also known as Jacobus Berengarius Carpensis, Jacopo Barigazzi, Giacomo Berengario da Carpi or simply Carpus; c. 1460 – c. 1530) was an Italian physician. His book "''Isagoge breves''" published in 1522 made him the mo ...

in his ''Commentaria super anatomia Mundini'' (1521).

Andreas Vesalius Andreas Vesalius (Latinized from Andries van Wezel) () was a 16th-century anatomist, physician, and author of one of the most influential books on human anatomy, ''De Humani Corporis Fabrica Libri Septem'' (''On the fabric of the human body'' '' ...

, in his ''

De humani corporis fabrica ''De Humani Corporis Fabrica Libri Septem'' (Latin, lit. "On the fabric of the human body in seven books") is a set of books on human anatomy written by Andreas Vesalius (1514–1564) and published in 1543. It was a major advance in the history ...

'', 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