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Middle Ear Bone Complex
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 incudomalleola ... [...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] |
Conductive Hearing Loss
Conductive hearing loss (CHL) is a type of hearing impairment that occurs when sound waves are unable to efficiently travel through the outer ear, tympanic membrane (eardrum), or middle ear structures such as the ossicles. This blockage or dysfunction prevents sound from being effectively conducted to the inner ear, resulting in reduced hearing ability. Common causes include ear infections, fluid in the middle ear, earwax buildup, damage to the eardrum, or abnormalities in the ossicles. CHL can occur alone or alongside sensorineural hearing loss, in which case it is classified as mixed hearing loss. Depending on the underlying cause, conductive hearing loss is often treatable and sometimes reversible through medical interventions, such as medication, surgery, or assistive devices like hearing aids. However, chronic or permanent cases may require long-term management to improve hearing and communication abilities. Causes Common causes of conductive hearing loss include: Exter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dentary
In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone is the skull's only movable, posable bone, sharing joints with the cranium's temporal bones. The mandible hosts the lower teeth (their depth delineated by the alveolar process). Many muscles attach to the bone, which also hosts nerves (some connecting to the teeth) and blood vessels. Amongst other functions, the jawbone is essential for chewing food. Owing to the Neolithic advent of agriculture (), human jaws evolved to be smaller. Although it is the strongest bone of the facial skeleton, the mandible tends to deform in old age; it is also subject to fracturing. Surgery allows for the removal of jawbone fragments (or its entirety) as well as regenerative methods. Additionally, the bone is of great forensic significance. Structure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inner Ear
The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance. In mammals, it consists of the bony labyrinth, a hollow cavity in the temporal bone of the skull with a system of passages comprising two main functional parts: * The cochlea, dedicated to hearing; converting sound pressure patterns from the outer ear into electrochemical impulses which are passed on to the brain via the auditory nerve. * The vestibular system, dedicated to balance (ability), balance. The inner ear is found in all vertebrates, with substantial variations in form and function. The inner ear is innervated by the eighth cranial nerve in all vertebrates. Structure The labyrinth can be divided by layer or by region. Bony and membranous labyrinths The bony labyrinth, or osseous labyrinth, is the network of passages with bony walls lined with periosteum. The three major parts of the bony labyrin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vestibule Of The Ear
The vestibule is the central part of the bony labyrinth in the inner ear, and is situated medial to the eardrum, behind the cochlea, and in front of the three semicircular canals. The name comes from the Latin ', literally an entrance hall. Structure The vestibule is somewhat oval in shape, but flattened transversely; it measures about 5 mm from front to back, the same from top to bottom, and about 3 mm across. In its lateral or tympanic wall is the oval window, closed, in the fresh state, by the base of the stapes and annular ligament. On its medial wall, at the forepart, is a small circular depression, the recessus sphæricus, which is perforated, at its anterior and inferior part, by several minute holes (macula cribrosa media) for the passage of filaments of the acoustic nerve to the saccule; and behind this depression is an oblique ridge, the crista vestibuli, the anterior end of which is named the pyramid of the vestibule. This ridge bifurcates below to e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oval Window
The oval window (or ''fenestra vestibuli'' or ''fenestra ovalis'') is a connective tissue membrane-covered opening from the middle ear to the cochlea of the inner ear. Vibrations that contact the tympanic membrane travel through the three ossicles and into the inner ear. The oval window is the intersection of the middle ear with the inner ear and is directly contacted by the stapes; by the time vibrations reach the oval window, they have been reduced in amplitude and increased in pressure due to the lever action of the ossicle bones. This is not an amplification function; rather, an impedance-matching function, allowing sound to be transferred from air (outer ear) to liquid (cochlea). It is a reniform (kidney-shaped) opening leading from the tympanic cavity into the vestibule of the inner ear; its long diameter is horizontal and its convex border is upward. It is occupied by the base of the ''stapes'', the circumference of which is fixed by the annular ligament to the margin of ... [...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] |
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 pressure of sound from the air to the ossicles inside the middle ear, and thence to the oval window in the fluid-filled cochlea. The ear thereby converts and amplifies vibration in the air to vibration in cochlear fluid. The malleus bone bridges the gap between the eardrum and the other ossicles. Rupture or perforation of the eardrum can lead to conductive hearing loss. Collapse or retraction of the eardrum can cause conductive hearing loss or cholesteatoma. Structure Orientation and relations The tympanic membrane is oriented obliquely in the anteroposterior, mediolateral, and superoinferior planes. Consequently, its superoposterior end lies lateral to its anteroinferior end. Anatomically, it relates superiorly to the middle crani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 changes in pressure of sound from the air to the ossicles inside the middle ear, and thence to the oval window in the fluid-filled cochlea. The ear thereby converts and amplifies vibration in the air to vibration in cochlear fluid. The malleus bone bridges the gap between the eardrum and the other ossicles. Rupture or perforation of the eardrum can lead to conductive hearing loss. Collapse or retraction of the eardrum can cause conductive hearing loss or cholesteatoma. Structure Orientation and relations The tympanic membrane is oriented obliquely in the anteroposterior, mediolateral, and superoinferior planes. Consequently, its superoposterior end lies lateral to its anteroinferior end. Anatomically, it relates superiorly to the middle cranial fos ... [...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] |
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 (usually a horse or other equine, such as a mule). They greatly increase the rider's ability to stay in the saddle and control the mount, increasing the animal's usefulness to humans in areas such as communication, transportation, and warfare. In antiquity, the earliest foot supports consisted of riders placing their feet under a girth or using a simple toe loop appearing in India by the 2nd century BC. Later, a single foot support was used as a mounting aid, and paired stirrups appeared after the invention of the treed saddle. The stirrup was invented in the Chinese Jin dynasty during the 4th century, was in common use throughout China by the 5th century, and was spread across Eurasia to Europe through the nomadic peoples of Centra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
