How many ossicles are there in each human ear?
"the upper jaw (the articular and quadrate bones) lost their purpose in the jaw joint and were put to new use in the middle ear, connecting to the existing stapes bone and forming a chain of three bones, the ossicles, which transmit sounds more efficiently and allow more acute hearing. In mammals, these three bones are known as the malleus, incus, and stapes (hammer, anvil, and stirrup respectively). Mammals and birds also differ from other vertebrates by having evolved a cochlea. The evidence that the malleus and incus are homologous to the reptilian articular and quadrate was originally embryological, and"
"tectorial membrane within the cochlea (See Figure 3). The tunnel of corti, which runs through the Organ of Corti, divides the OHCs and the inner hair cells (IHCs). OHCs are connected to the reticular laminar and the Deiters’ cells. There are roughly twelve thousand OHCs in each human ear, and these are arranged in up to five rows. Each OHC has small tufts of 'hairs', or cilia, on their upper surface known as stereocilia, and these are also arranged into rows which are graded in height. There are approximately 140 stereocilia on each OHC. The fundamental role of the OHCs"
"is also a second auditory ossicle, the ""operculum"" (not to be confused with the structure of the same name in fishes). This is a flat, plate-like bone, overlying the fenestra ovalis, and connecting it either to the stapes or, via a special muscle, to the scapula. It is not found in any other vertebrates. Mammals are unique in having evolved a three-ossicle middle-ear independently of the various single-ossicle middle ears of other land vertebrates, all during the Triassic period of geological history. Functionally, the mammalian middle ear is very similar to the single-ossicle ear of non-mammals, except that it responds"
"ear of most mammals, sound is filtered differently on its way into the ear depending on what vertical location it is coming from. This gives these animals the ability to localize sound vertically. The eardrum is an airtight membrane, and when sound waves arrive there, they cause it to vibrate following the waveform of the sound. The middle ear consists of a small air-filled chamber that is located medial to the eardrum. Within this chamber are the three smallest bones in the body, known collectively as the ossicles which include the malleus, incus, and stapes (also known as the hammer,"
"saccule. The otolith organs are beds of sensory cells in the inner ear, specifically small patches of hair cells. Overlying the hair cells and their hair bundles is a gelatinous layer and above that layer is the otolithic membrane. The utricle serves to measure horizontal accelerations and the saccule responds to vertical accelerations. The reason for this difference is the orientation of the macula in the two organs. The utricular macula lie horizontal in the utricle, while the saccular macula lies vertical in the saccule. Every hair cell in these sensory beds consist of 40-70 stereocilia and a kinocilium. The"
"of the inner ear. In other words, it is the mechanical transfer function that allows for efficient transfer of collected sound energy between two different media. The three small bones that are responsible for this complex process are the malleus, the incus, and the stapes, collectively known as the ear ossicles. The impedance matching is done through via lever ratios and the ratio of areas of the tympanic membrane and the footplate of the stapes, creating a transformer-like mechanism. Furthermore, the ossicles are arranged in such a manner as to resonate at 700–800 Hz while at the same time protecting"
"Berengario da Carpi in his ""Commentaria super anatomia Mundini"" (1521). Andreas Vesalius, 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. Incus The incus or anvil is a bone in the middle ear. The anvil-shaped small bone is one of three ossicles in the middle ear. The ""incus"" receives vibrations from the malleus, to which it is connected laterally, and transmits these to the"
"Otolith An otolith (, ' ear + , ', a stone), also called statoconium or otoconium or statolith, is a calcium carbonate structure in the saccule or utricle of the inner ear, specifically in the vestibular system of vertebrates. The saccule and utricle, in turn, together make the ""otolith organs"". These organs are what allows an organism, including humans, to perceive linear acceleration, both horizontally and vertically (gravity). They have been identified in both extinct and extant vertebrates. Counting the annual growth rings on the otoliths is a common technique in estimating the age of fish. Endolymphatic infillings such as"
"bones present in reptiles. The ossicles are classically supposed to mechanically convert the vibrations of the eardrum, into amplified pressure waves in the fluid of the cochlea (or inner ear) with a lever arm factor of 1.3. Since the effective vibratory area of the eardrum is about 14 fold larger than that of the oval window, the sound pressure is concentrated, leading to a pressure gain of at least 18.1. The eardrum is merged to the malleus, which connects to the incus, which in turn connects to the stapes. Vibrations of the stapes footplate introduce pressure waves in the inner"
"Mechanically, bones also have a special role in hearing. The ossicles are three small bones in the middle ear which are involved in sound transduction. The cancellous part of bones contain bone marrow. Bone marrow produces blood cells in a process called hematopoiesis. Blood cells that are created in bone marrow include red blood cells, platelets and white blood cells. Progenitor cells such as the hematopoietic stem cell divide in a process called mitosis to produce precursor cells. These include precursors which eventually give rise to white blood cells, and erythroblasts which give rise to red blood cells. Unlike red"
"Utricle (ear) The utricle, along with the saccule, is one of the two otolith organs located in the vertebrate inner ear. The utricle and the saccule are parts of the balancing apparatus (membranous labyrinth) located within the vestibule of the bony labyrinth (small oval chamber). These use small stones and a viscous fluid to stimulate hair cells to detect motion and orientation. The utricle detects linear accelerations and head-tilts in the horizontal plane. The word utricle comes . The utricle is larger than the saccule and is of an oblong form, compressed transversely, and occupies the upper and back part"
"set of bones known as ""Weberian ossicles"", a chain of small bones that connect the auditory system to the gas bladder of fishes. The ossicles connect the gas bladder wall with Y-shaped lymph sinus that abuts the lymph-filled transverse canal joining the sacculi of the right and left ears. This allows the transmission of vibrations to the inner ear. In anotophysians, the three first vertebrae are specialized and associated with one or more cephalic ribs (a primitive Weberian apparatus). In the otophysians, a distinct modification of the anterior four or five first vertebrae is found, as well as the Weberian"
"elastic cartilage with a complicated relief on its inner surface and a fairly smooth configuration on its posterior surface. A tubercle, known as Darwin's tubercle, is sometimes present, lying in the descending part of the helix and corresponding to the ear-tip of mammals. The earlobe consists of areola and adipose tissue. The symmetrical arrangement of the two ears allows for the localisation of sound. The brain accomplishes this by comparing arrival-times and intensities from each ear, in circuits located in the superior olivary complex and the trapezoid bodies which are connected via pathways to both ears. The middle ear lies"
"Incus The incus or anvil is a bone in the middle ear. The anvil-shaped small bone is one of three 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 so-called because of its resemblance to an anvil (). The incus is the second of the ossicles, three 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"
"anvil, and stirrup, respectively). They aid in the transmission of the vibrations from the eardrum into the inner ear, the cochlea. The purpose of the middle ear ossicles is to overcome the impedance mismatch between air waves and cochlear waves, by providing impedance matching. Also located in the middle ear are the stapedius muscle and tensor tympani muscle, which protect the hearing mechanism through a stiffening reflex. The stapes transmits sound waves to the inner ear through the oval window, a flexible membrane separating the air-filled middle ear from the fluid-filled inner ear. The round window, another flexible membrane, allows"
"to structures in the brainstem for further processing. The ""stapes"" (stirrup) ossicle bone of the middle ear transmits vibrations to the ""fenestra ovalis"" (oval window) on the outside of the cochlea, which vibrates the perilymph in the ""vestibular duct"" (upper chamber of the cochlea). The ossicles are essential for efficient coupling of sound waves into the cochlea, since the cochlea environment is a fluid–membrane system, and it takes more pressure to move sound through fluid–membrane waves than it does through air; a pressure increase is achieved by the area ratio of the tympanic membrane to the oval window, resulting in"
"Malleus The malleus or hammer is a hammer-shaped small bone or ossicle of the middle ear which 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"". The malleus is a bone situated in the middle ear. It is the first of the three ossicles, and attached to the 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"", and the bone"
"the ossicular chain. Damage to the inner ear (cochlea) may be caused by temporal bone fracture. People who sustain head injury are especially vulnerable to hearing loss or tinnitus, either temporary or permanent. Sound waves reach the outer ear and are conducted down the ear canal to the eardrum, causing it to vibrate. The vibrations are transferred by the 3 tiny ear bones of the middle ear to the fluid in the inner ear. The fluid moves hair cells (stereocilia), and their movement generates nerve impulses which are then taken to the brain by the cochlear nerve. The auditory nerve"
"the developing embryo consists of three layers: endoderm, mesoderm and ectoderm. The first part of the ear to develop is the inner ear, which begins to form from the ectoderm around the 22nd day of the embryo’s development. Specifically, the inner ear derives from two thickenings called otic placodes on either side of the head. Each otic placode recedes below the ectoderm, forms an otic pit and then an otic vesicle. This entire mass will eventually become surrounded by mesenchyme to form the bony labyrinth. Around the 33rd day of development, the vesicles begin to differentiate. Closer to the back"
"prey taxa. The inclusion of fish vertebrae, jaw bones, teeth, and other informative skeletal elements improves prey identification and quantification over otolith analysis alone. This is especially true for fish species with fragile otoliths, but other distinctive bones, such as Atlantic mackerel (""Scomber scombrus""), and Atlantic herring (""Clupea harengus""). Otolith An otolith (, ' ear + , ', a stone), also called statoconium or otoconium or statolith, is a calcium carbonate structure in the saccule or utricle of the inner ear, specifically in the vestibular system of vertebrates. The saccule and utricle, in turn, together make the ""otolith organs"". These"
"the inner ear from excessive energy. A certain degree of top-down control is present at the middle ear level primarily through two muscles present in this anatomical region: the tensor tympani and the stapedius. These two muscles can restrain the ossicles so as to reduce the amount of energy that is transmitted into the inner ear in loud surroundings. The cochlea of the inner ear, a marvel of physiological engineering, acts as both a frequency analyzer and nonlinear acoustic amplifier. The cochlea has over 32,000 hair cells. Outer hair cells primarily provide amplification of traveling waves that are induced by"
"the utricle, the other called the saccule. The utricle contains a patch of hair cells and supporting cells called a macula. Similarly, the saccule contains a patch of hair cells and a macula. Each hair cell of a macula has 40-70 stereocilia and one true cilium called a kinocilium. The tips of these cilia are embedded in an otolithic membrane. This membrane is weighted down with protein-calcium carbonate granules called otoliths. These otoliths add to the weight and inertia of the membrane and enhance the sense of gravity and motion. With the head erect, the otolithic membrane bears directly down"
"The otolith organs (utricle and saccule) are sensors for detecting linear acceleration in their respective planes (utrical=horizontal plane (forward/backward; up/down); saccule=sagital plane (up/down)), and the three semicircular canals (anterior/superior, posterior, and horizontal) detect head rotation or angular acceleration in their respective planes of orientation (anterior/superior=pitch (nodding head), posterior=roll (moving head from one shoulder to other), and horizontal=yaw (shaking head left to right). Located within the membranous labyrinthine walls of the vestibular system are approximately 67,000 hair cells in total. This includes ~7,000 hair cells from each of the semicircular canals located within the crista ampullaris, ~30,000 hair cells from the"
"vibration of the ossicles, in order to protect the inner ear from excessively loud noise (theory 1) and that they give better frequency resolution at higher frequencies by reducing the transmission of low frequencies (theory 2) (see acoustic reflex). These muscles are more highly developed in bats and serve to block outgoing cries of the bats during echolocation (SONAR). Occasionally the joints between the ossicles become rigid. One condition, otosclerosis, results in the fusing of the stapes to the oval window. This reduces hearing and may be treated surgically. There is some doubt as to the discoverers of the auditory"
"otoliths are structures in the saccule and utricle of the inner ear, specifically in the vestibular labyrinth of all vertebrates (fish, amphibians, reptiles, mammals and birds). In vertebrates, the saccule and utricle together make the ""otolith organs"". Both statoconia and otoliths are used as gravity, balance, movement, and directional indicators in all vertebrates and have a secondary function in sound detection in higher aquatic and terrestrial vertebrates. They are sensitive to gravity and linear acceleration. Because of their orientation in the head, the utricle is sensitive to a change in horizontal movement, and the saccule gives information about vertical acceleration"
"laterally. The evolutionary process leading to a three-ossicle middle ear was thus an ""accidental"" byproduct of the simultaneous evolution of the new, secondary jaw joint. In many mammals, the middle ear also becomes protected within a cavity, the auditory bulla, not found in other vertebrates. A bulla evolved late in time and independently numerous times in different mammalian clades, and it can be surrounded by membranes, cartilage or bone. The bulla in humans is part of the temporal bone. Middle ear The middle ear is the portion of the ear internal to the eardrum, and external to the oval window"
"eutriconodonts, the Meckel's cartilage still connected otherwise entirely modern ear bones to the jaw. Meckel's cartilage In humans, the cartilaginous bar of the mandibular arch is formed by what are known as Meckel’s cartilages (right and left) also known as Meckelian cartilages; above this the incus and malleus are developed. Meckel's cartilage arises from the first pharyngeal arch. The dorsal end of each cartilage is connected with the ear-capsule and is ossified to form the malleus; the ventral ends meet each other in the region of the symphysis menti, and are usually regarded as undergoing ossification to form that portion"
"brain, which influences their motility as part of the cochlea's mechanical pre-amplifier. The input to the OHC is from the olivary body via the medial olivocochlear bundle. The cochlear duct is almost as complex on its own as the ear itself. The cochlear duct is bounded on three sides by the basilar membrane, the stria vascularis, and Reissner's membrane. Stria vascularis is a rich bed of capillaries and secretory cells; Reissner's membrane is a thin membrane that separates endolymph from perilymph; and the basilar membrane is a mechanically somewhat stiff membrane, supporting the receptor organ for hearing, the organ of"
"via the pharyngeal opening of the Eustachian tube. The inner ear contains the otolith organs—the utricle and saccule—and the semicircular canals belonging to the vestibular system, as well as the cochlea of the auditory system. The outer ear is the external portion of the ear and includes the fleshy visible pinna (also called the auricle), the ear canal, and the outer layer of the eardrum (also called the tympanic membrane). The pinna consists of the curving outer rim called the helix, the inner curved rim called the antihelix, and opens into the ear canal. The tragus protrudes and partially obscures"
"total resulting in hearing loss of different degree. Scar tissue after ear infections may also make the eardrum dysfunction as well as when it is retracted and adherent to the medial part of the middle ear. Dysfunction of the three small bones of the middle ear – malleus, incus, and stapes – may cause conductive hearing loss. The mobility of the ossicles may be impaired for different reasons including a boney disorder of the ossicles called otosclerosis and disruption of the ossicular chain due to trauma, infection or ankylosis may also cause hearing loss. Sensorineural hearing loss is one caused"
"with agility, as shown with several mammals. Curvature and size of these canals seems to affect agility, and may be due to the environments in which animals navigate, such as a mostly two-dimensional landscape as compared to three-dimensional spaces (i.e. in the air, the trees, or the water). The otoliths have two components: the utricle and the saccule. Both are made of the same sensory tissue containing hair cells, which is covered by a gelatinous layer and the otolithic membrane on top. Embedded in this membrane are calcium carbonate crystals, called otoconia, or ""ear rocks."" As the head is tilted"
"Pike or Jack fish, which he understood to be their organs of hearing, though he did not discover any manifest external auditory passages. In section of the essay titled ""De Lapillis, eorumque Numero in Craniis Piscium"" (roughly translated as “The bones, their number in the skull of Fish”) Klein considers what parts of the head of fish serve as the organ of hearing, and by what passages the sensation of sound is communicated to them. He refers to these bones as Ossicula – little bones – and considers them essential parts of the head, generated with the brain itself. He"
"stirrup and act to decrease sound before it hits the inner ear. In general, the ossicles act as a barrier to the inner ear for sound energy. Inner ear Inner ear fluid called endolymph receives the sound energy. After receiving the energy, later within the inner ear there are two parts: the cochlea that utilizes sound waves from the ossicles and the vestibular apparatus that manages the rabbit's position in regards to movement. Within the cochlea there is a basilar membrane that contains sensory hair structures utilized to send nerve signals to the brain so it can recognize different sound"