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Incus
The ''incus'' (: 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 (). Structure The incus is the second of three ossicles, very small bones in the middle ear which act to transmit sound. It is shaped like an anvil, 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 incus is Homology (biology), homologous to the quadrate bone found in other tetrapods. Function Vibrations in the middle ear are received via the tympanic membrane. The malleus, resting on the membrane, conveys vibrations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 ''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. Structure The ossicles are, in order from the eardrum to the inner ear (from superficial to deep): the malleus, incus, and stapes, terms that in Latin are translated as "the hammer, anvil, and stirrup". * The malleus () articulates with the incus through the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 of the eardrum into waves in the fluid and membranes of the inner ear. The hollow space of the middle ear is also known as the tympanic cavity and is surrounded by the tympanic part of the temporal bone. The auditory tube (also known as the Eustachian tube or the pharyngotympanic tube) joins the tympanic cavity with the nasal cavity ( nasopharynx), allowing pressure to equalize between the middle ear and throat. The primary function of the middle ear is to efficiently transfer acoustic energy from compression waves in air to fluid–membrane waves within the cochlea. Structure Ossicles The middle ear contains three tiny bones known as the ossicles: '' malleus'', ''incus'', and '' stapes''. The ossicles were given their Latin names f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 from the eardrum to the ''incus'' (anvil). Structure The malleus is a bone situated in the middle ear. It is the first of the three ossicles, and attached to the eardrum (tympanic membrane). The head of the malleus is the large protruding section, which attaches to the incus. The head connects to the neck of malleus. The bone continues as the handle (or manubrium) of malleus, which connects to the tympanic membrane. Between the neck and handle of the malleus, lateral and anterior processes emerge from the bone. The bone is oriented so that the head is superior and the handle is inferior. Development Embryologically, the malleus is derived from the first pharyngeal arch along with the ''incus''. In humans it grows from Meckel's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 role in the vibration of the middle ear bones: together with the anterior ligament of the malleus The ligaments of malleus are three ligaments that attach the malleus in the middle ear. They are the anterior, lateral and superior ligaments. The anterior ligament of the malleus also known as Casserio's ligament is a fibrous band that exten ..., it forms a pivotal axis around which the ossicles rotate. This rotation conveys vibrations from the tympanum to the oval window on the bony labyrinth (where they can be transduced into electrical signals transmitted to the nervous system). References Human head and neck Ligaments {{ligament-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Incudostapedial Joint
The incudostapedial joint is a small, synovial ball-and-socket joint between the ''incus'' (anvil) and the '' stapes'' (stirrup). The joint's function is to transfer vibrations between the two ossicles. The incudostapedial joint lies between the long leg of the incus (long crus, or ''crus longum incudis'') and the head of the ''stapes'' (''caput stapedis''). The long leg moves with the rest of the ''incus,'' and a small knob, the lenticular process, articulates with the head of the ''stapes''. Biophysics Although the joint is synovial, it nonetheless allows only for a very limited, linear range of motion. All of the ossicles move almost as a single unit. As the transfer of kinetic energy from the incident sound waves to the perilymph of the inner ear involves a loss of energy, the ossicular system functions to compensate for the loss by decreasing the lever ratio between the surface of the eardrum and the base of the ''stapes'', but also through the ratio between the ''manubri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Incudomalleolar Joint
The incudomalleolar joint (also called incudomallear joint, or malleoincudal joint) or articulatio incudomallearis is a small saddle-type synovial joint between the malleus (hammer) and the incus (anvil). The joint's function is to transfer vibrations between the ossicles in the middle ear, which is perceived as sound. It may also play a role in protecting the inner ear during changes in static air pressure. Contrary to other synovial joints the movement is very limited. All of the ossicles move more or less as a unit, at least at low frequencies. When the eardrum 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 changes in pres ... is moved inward due to sound vibrations, transferred through the outer ear, it transmits to the handle or manubrium of the malleus which is connected to the ear drum. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadrate Bone
The quadrate bone is a skull bone in most tetrapods, including amphibians, sauropsids ( reptiles, birds), and early synapsids. In most tetrapods, the quadrate bone connects to the quadratojugal and squamosal bones in the skull, and forms upper part of the jaw joint. The lower jaw articulates at the articular bone, located at the rear end of the lower jaw. The quadrate bone forms the lower jaw articulation in all classes except mammals. Evolutionarily, it is derived from the hindmost part of the primitive cartilaginous upper jaw. Function in reptiles In certain extinct reptiles, the variation and stability of the morphology of the quadrate bone has helped paleontologists in the species-level taxonomy and identification of mosasaur squamates and spinosaurine dinosaurs. In some lizards and dinosaurs, the quadrate is articulated at both ends and movable. In snakes, the quadrate bone has become elongated and very mobile, and contributes greatly to their ability to swallow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stapes
The ''stapes'' or stirrup is a bone in the middle ear of humans and other tetrapods 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 footplate (or base) to transmit sound energy through the oval window into the inner ear. The ''stapes'' is the smallest and lightest bone in the human body, and is so-called because of its resemblance to a stirrup (). Structure The ''stapes'' is the third bone of the three ossicles in the middle ear and the smallest in the human body. It measures roughly , greater along the head-base span. It rests on the oval window, to which it is connected by an annular ligament and articulates with the ''incus'', or anvil through the incudostapedial joint. They are connected by anterior and posterior limbs (). Development The ''stapes'' develops from the second pharyngeal arch during the sixth to eighth week of embryological life. The central ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 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 vibra .... Ear Ligaments {{ligament-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homology (biology)
In biology, homology is similarity in anatomical structures or genes between organisms of different taxa due to shared ancestry, ''regardless'' of current functional differences. Evolutionary biology explains homologous structures as retained heredity from a common descent, common ancestor after having been subjected to adaptation (biology), adaptive modifications for different purposes as the result of natural selection. The term was first applied to biology in a non-evolutionary context by the anatomist Richard Owen in 1843. Homology was later explained by Charles Darwin's theory of evolution in 1859, but had been observed before this from Aristotle's biology onwards, and it was explicitly analysed by Pierre Belon in 1555. A common example of homologous structures is the forelimbs of vertebrates, where the bat wing development, wings of bats and origin of avian flight, birds, the arms of primates, the front flipper (anatomy), flippers of whales, and the forelegs of quadrupedalis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
