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Encyclopedia > Ossicles
Ossicles
Ossicles
Chain of ossicles and their ligaments, seen from the front in a vertical, transverse section of the tympanum.
Latin membrana tympani
Gray's subject #231 1044
MeSH Ear+Ossicles

The ossicles (also called auditory ossicles) are the three smallest bones in the human body. They are contained within the middle ear space and serve to transmit sounds from the air to the fluid-filled labyrinth (cochlea). The absence of the auditory ossicles would constitute a moderate to severe hearing loss. Image File history File links Gray919. ... For other uses, see Latins and Latin (disambiguation). ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... This article is about the skeletal organs. ... The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the cochlea. ... This article is about audible acoustic waves. ... For more uses of the word labyrinth, see Labyrinth (disambiguation) The labyrinth is a system of fluid passages in the inner ear, including both the cochlea which is part of the auditory system, and the vestibular system which provides the sense of balance. ... The cochlea is the auditory portion of the inner ear. ...

Contents

Development

Studies have shown that ear bones in mammal embryos are attached to the dentary, which is part of the jaw. These are ossified portions of cartilage that are attached to the jaw. This is called Meckel's cartilage. As the embryo develops, the cartilage hardens to form bone. Later in development, the bone structure breaks loose from the jaw and migrates to the inner ear area. The structure is known as the middle ear and is made up of the incus, stapes, malleus, and tympanic membrane. These correspond to the quadrate, preartiluar, articular, and angular structures in the reptile jaw. For this reason, researchers believe the similarity is because of mammals and reptiles sharing a common ancestor.[1] The dentary is the tooth bearing bone of the lower jaw. ... Cartilage is a type of dense connective tissue. ... The cartilaginous bar of the mandibular arch is formed by what are known as Meckel’s cartilages (right and left) ; above this the incus is developed. ... The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the cochlea. ... This article refers to a bone in the mammalian ear. ... The stapes or stirrup is the stirrup-shaped small bone or ossicle in the middle ear which attaches the incus to the fenestra ovalis, the oval window which is adjacent to the vestibule of the inner ear. ... The malleus is 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 tympanum or tympanic membrane, colloquially known as eardrum, is a thin membrane that separates the outer ear from the middle ear. ... The quadrate is a jaw bone in all jawed vertebrates except mammals (in whom it has become a middle-ear bone, the incus). ... The articular is a bone in the lower jaw of most tetrapods, including reptiles, birds, and amphibians, but has become a middle ear bone (the malleus) in mammals. ... The angular is a large bone in the lower jaw of amphibians, birds and reptiles, which is connected to all other lower jaw bones: the dentary (which is the entire lower jaw in mammals), the splenial, the suprangular, and the articular Also see: Angular momentum. ...


Anatomy

The ossicles are, in order from the eardrum to the inner ear, the hammer, anvil, and stirrup, so named because of the size of the bones. They are also commonly referred to by the equivalent Latin terms: malleus, incus, and stapes respectively. The malleus is 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. ... This article refers to a bone in the mammalian ear. ... The stapes or stirrup is the stirrup-shaped small bone or ossicle in the middle ear which attaches the incus to the fenestra ovalis, the oval window which is adjacent to the vestibule of the inner ear. ...

  • The malleus articulates with the incus and is attached to the tympanic membrane (eardrum), from which vibrational energy is passed.
  • The incus is connected to both the other bones.
  • The stapes articulates with the incus and is attached to the membrane of the fenestra ovalis, the elliptical or oval window or opening between the middle ear and the vestibule of the inner ear.

The tympanum or tympanic membrane, colloquially known as eardrum, is a thin membrane that separates the outer ear from the middle ear. ... The tympanic membrane, colloquially known as the eardrum, is a thin membrane that separates the external ear from the middle ear. ... The fenestra ovalis or oval window is a membrane-covered opening which leads from the middle ear to the vestibule of the inner ear. ... This is a page about the part of the ear. ... For other uses, see Ear (disambiguation). ...

Function

As sound waves vibrate the tympanic membrane (eardrum), it in turn moves the nearest ossicle, the malleus, to which it is attached. The malleus then transmits the vibrations, via the incus, to the stapes, and so ultimately to the membrane of the fenestra ovalis, the opening to the vestibule of the inner ear.


The ossicles give the eardrum mechanical advantage via lever action and a reduction in the area of force distribution; the resulting vibrations would be much smaller if the sound waves were transmitted directly from the outer ear to the oval window. However, the extent of the movements of the ossicles is controlled (and constricted) by certain muscles attached to them (the tensor tympani and the stapedius). It is believed that these muscles can contract to dampen 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). In physics and engineering, mechanical advantage (MA) is the factor by which a mechanism multiplies the force put into it. ... The tensor tympani muscle arises from the auditory tube and inserts onto the handle of the malleus, damping down vibration in the ossicles and so reducing the amplitude of sounds. ... The stapedius is the smallest striated muscle in the human body. ... The acoustic reflex (or stapedius reflex) is an involuntary muscle contraction that occurs in the middle ear of mammals in response to high-intensity sound stimuli. ... For the flying mammal see bat. ... See: Animal echolocation: animals emitting sound waves and listening to the echo in order to locate objects or navigate. ...


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. Otosclerosis is a progressive degenerative condition of the temporal bone which can result in hearing loss. ...


References

  1. ^ Meng, Jin. "The Journey From Jaw to Ear." Biologist. vol. 50. (2003) p. 154-158.

External links

  • The middle ear and the ossicles

The human eye is the first element of a sensory system: in this case, vision, for the visual system. ... The auditory system is the sensory system for the sense of hearing. ... The vestibular system, or balance system, is the sensory system that provides the dominant input about movement and equilibrioception. ... The outer ear is the external portion of the ear. ... A left human ear. ... On the pinna, a curved prominence of cartilage, parallel with and in front of the helix, is called the antihelix, also known as the anthelix; this divides above into two crura, between which is a triangular depression, the fossa triangularis. ... In front of the concha, and projecting backward over the meatus, is a small pointed eminence, the tragus, so called from its being generally covered on its under surface with a tuft of hair, resembling a goat’s beard. ... Opposite the tragus, and separated from it by the intertragic notch, is a small tubercle, the antitragus. ... On the ear of humans and many other animals, the earlobe(lobulus auriculæ), sometimes simply lobe or lobule) is the soft lower part of the external ear, similar in composition to the labia, or pinna. ... The ear canal (external auditory meatus, external acoustic meatus), is a tube running from the outer ear to the middle ear. ... The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the cochlea. ... The tympanic membrane, colloquially known as the eardrum, is a thin membrane that separates the external ear from the middle ear. ... The umbo is the most depressed part of the tympanic membrane. ... The malleus is 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. ... This article refers to a bone in the mammalian ear. ... The stapes or stirrup is the stirrup-shaped small bone or ossicle in the middle ear which attaches the incus to the fenestra ovalis, the oval window which is adjacent to the vestibule of the inner ear. ... The stapedius is the smallest striated muscle in the human body. ... The tensor tympani muscle arises from the auditory tube and inserts onto the handle of the malleus, damping down vibration in the ossicles and so reducing the amplitude of sounds. ... The Eustachian tube (or auditory tube) is a tube that links the pharynx to the middle ear. ... The base of the cartilaginous portion of the Eustachian tube lies directly under the mucous membrane of the nasal part of the pharynx, where it forms an elevation, the torus tubarius or cushion, behind the pharyngeal orifice of the tube. ... Inner ear The inner ear is the bony labyrinth, a system of passages comprising two main functional parts: the organ of hearing, or cochlea and the vestibular apparatus, the organ of balance that consists of three semicircular canals and the vestibule. ... For more uses of the word labyrinth, see Labyrinth (disambiguation) The labyrinth is a system of fluid passages in the inner ear, including both the cochlea which is part of the auditory system, and the vestibular system which provides the sense of balance. ... The bony labyrinth (osseous labyrinth) consists of three parts: vestibule semicircular canals cochlea These are cavities hollowed out of the substance of the bone, and lined by periosteum; they contain a clear fluid, the perilymph, in which the membranous labyrinth is situated. ... This is a page about the part of the ear. ... The membranous labyrinth is lodged within the bony labyrinth, and has the same general form; it is, however, considerably smaller, and is partly separated from the bony walls by a quantity of fluid, the perilymph. ... The helicotrema is the part of the cochlear labyrinth where the scala tympani and the scala vestibuli meet. ... The round window is one of two membranes that separates the inner ear from the middle ear. ... The cochlea is the auditory portion of the inner ear. ... The spiral ganglion is the group of nerve cells that serve the sense of hearing by sending a representation of sound from the cochlea to the brain. ... The modiolus is a conical shaped central axis in the cochlea. ... The cochlear duct (or scala media) is an endolymph filled cavity inside the cochlea, located in between the scala tympani and the scala vestibuli, separated by the basilar membrane and Reissners membrane (the vestibular membrane) respectively. ... Endolymph is the fluid contained in the membranous labyrinth of the inner ear. ... The upper portion of the spiral ligament contains numerous capillary loops and small blood vessels, and is termed the stria vascularis. ... The periosteum, forming the outer wall of the ductus cochlearis, is greatly thickened and altered in character, and is called the spiral ligament. ... The organ of Corti is the organ in the inner ear of mammals that contains auditory sensory cells, or hair cells. // Structure and function It has highly specialized structures that respond to fluid-borne vibrations in the cochlea with a shearing vector in the hairs of some cochlear hair cells. ... Scala vestibuli is a perilymph filled cavity inside the cochlea of the inner ear. ... Scala tympani is the name of one of the perilymph filled cavities in the cochlear labyrinth. ... Perilymph is a fluid located within the cochlea (part of the ear) in 2 of its 3 muscles; the scala typmani and scala vestibuli. ... Reissners membrane is a membrane inside the cochlea of the inner ear, it separates scala media from scala vestbuli and together with the basilar membrane it creates a compartment in the cochlea filled with perilymph, which is important for the function of the organ of Corti inside the scala... Cross section of the cochlea. ... Covering the sulcus spiralis internus and the spiral organ of Corti is the tectorial membrane, which is attached to the limbus laminae spiralis close to the inner edge of the vestibular membrane. ... The organ of Corti is the organ in the inner ear of mammals that contains auditory sensory cells, or hair cells. // Structure and function It has highly specialized structures that respond to fluid-borne vibrations in the cochlea with a shearing vector in the hairs of some cochlear hair cells. ... Hair cells are the sensory cells of both the auditory system and the vestibular system in all vertebrates. ... Section through the spiral organ of Corti. ... The basilar crest gives attachment to the outer edge of the basilar membrane; immediately above the crest is a concavity, the sulcus spiralis externus. ... On the upper plate of that part of the lamina which is outside the vestibular membrane, the periosteum is thickened to form the limbus laminæ spiralis, this ends externally in a concavity, the sulcus spiralis internus, which represents, on section, the form of the letter C. Histology at uc. ... The osseous spiral lamina consists of two plates of bone, and between these are the canals for the transmission of the filaments of the acoustic nerve. ... The vestibular system, or balance system, is the sensory system that provides the dominant input about movement and equilibrioception. ... The utricle, larger than the saccule, is of an oblong form, compressed transversely, and occupies the upper and back part of the vestibule, lying in contact with the recessus ellipticus and the part below it. ... The portion of the utricle which is lodged in the recess forms a sort of pouch or cul-de-sac, the floor and anterior wall of which are thickened, and form the macula of utricle, which receives the utricular filaments of the acoustic nerve. ... Categories: Stub ... The saccule is the smaller of the two vestibular sacs; it is globular in form, and lies in the recessus sphæricus near the opening of the scala vestibuli of the cochlea. ... From the posterior wall of the saccule a canal, the ductus endolymphaticus, is given off; this duct is joined by the ductus utriculosaccularis, and then passes along the aquaeductus vestibuli and ends in a blind pouch, the endolymphatic sac, on the posterior surface of the petrous portion of the temporal... From the posterior wall of the saccule a canal, the endolymphatic duct, is given off; this duct is joined by the ductus utriculosaccularis, and then passes along the aquaeductus vestibuli and ends in a blind pouch (saccus endolymphaticus) on the posterior surface of the petrous portion of the temporal bone... A kinocilium is a special structure connected to the hair cells of the inner ears cochlea. ... An otolith, (oto-, ear + lithos, a stone), also called statoconium[1] or otoconium is a structure in the saccule or utricle of the inner ear, specifically in the vestibular labyrinth. ... inner ear illustration showing semicircular canal, hair cells, ampulla, cupula, vestibular nerve, & fluid The semicircular canals are three half-circular, interconnected tubes located inside each ear that are the equivalent of three gyroscopes located in three planes perpendicular (at right angles) to each other. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... The posterior semicircular canal, vertical like the superior, is directed backward, nearly parallel to the posterior surface of the petrous bone; it is the longest of the three canals, measuring from 18 to 22 mm. ... The lateral or horizontal canal (external semicircular canal) is the shortest of the three canals. ... The cupula forms the apex of the cochlea. ... The bony semicircular canals are three in number, superior, posterior, and lateral, and are situated above and behind the vestibule. ... This article does not cite any references or sources. ... For other uses, see Brain (disambiguation). ... The Cochlear nerve (n. ... The vestibulocochlear nerve (also known as the auditory or acoustic nerve) is the eighth of twelve cranial nerves, and is responsible for transmitting sound and equilibrium (balance) information from the inner ear to the brain. ... The cochlear nuclei consist of: (a) the dorsal cochlear nucleus, corresponding to the tuberculum acusticum on the dorso-lateral surface of the inferior peduncle; and (b) the ventral or accessory cochlear nucleus, placed between the two divisions of the nerve, on the ventral aspect of the inferior peduncle. ... The trapezoid body is part of the acoustic pathway. ... For the cerebellar structure, see Dentate nucleus. ... The lateral lemniscus is a tract of axons in the brainstem that carries information about sound from the cochlear nucleus to various brainstem nuclei and ultimately the contralateral inferior colliculus of the midbrain. ... The paired inferior colliculi together with the superior colliculi form the eminences of the corpora quadrigemina. ... The medial geniculate nucleus is a nucleus of the thalamus that acts as a relay for auditory information. ... The primary auditory cortex is the region of the brain that is responsible for processing of auditory (sound) information. ... This article is about the skeletal organs. ... diagram of the axial skeleton The axial skeleton consists of the 80 bones in the head and trunk of the human body. ... Appendicular skeleton diagram The appendicular skeleton, consisting of 126 bones, makes body movement possible and protects the organs of digestion, excretion, and reproduction. ... The vertebral column seen from the side Different regions (curvatures) of the vertebral column The vertebral column (backbone or spine) is a column of vertebrae situated in the dorsal aspect of the abdomen. ... A diagram of a thoracic vertebra. ... In vertebrates, cervical vertebrae (singular: vertebra) are those vertebrae immediately behind (caudal to) the skull. ... A typical thoracic vertebra The thoracic vertebrae (vertebrae thoracales) compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. ... The lumbar vertebrae are the largest segments of the movable part of the vertebral column, and are characterized by the absence of the foramen transversarium within the transverse process, and by the absence of facets on the sides of the body. ... For the record label, see Sacrum Torch. ... The coccyx is formed of up to five vertebrae. ... Male Chest The chest is a part of the anatomy of humans and various other animals. ... The sternum (from Greek στέρνον, sternon, chest) or breastbone is a long, flat bone located in the center of the thorax (chest). ... The human rib cage is a part of the human skeleton within the thoracic area. ... For other uses of Skull, see Skull (disambiguation). ... The occipital bone, a saucer-shaped membrane bone situated at the back and lower part of the cranium, is trapezoid in shape and curved on itself. ... The parietal bones (os parietale) are bones in the human skull and form, by their union, the sides and roof of the cranium. ... The frontal bone (os frontale, TA: A02. ... The temporal bones (os temporales) are situated at the sides and base of the skull. ... The sphenoid bone (from Greek sphenoeides, wedgelike) is a bone situated at the base of the skull in front of the temporals and basilar part of the occipital bone. ... Your skull is in your back (this is obviously not true, I was just testing the website to see if it really works) The ethmoid bone (os ethmoidale) is a bone in the skull that separates the nasal cavity from the brain. ... For other uses of Skull, see Skull (disambiguation). ... The Nasal Bones (Ossa Faciei & Ossa Nasalia) are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face, and form, by their junction, the bridge of the nose. ... The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper jaw. ... The lacrimal bone (Os Lacrimale), the smallest and most fragile bone of the face, is situated at the front part of the medial wall of the orbit . ... The zygomatic bone (malar bone) is a paired bone of the human skull. ... The palatine bone is a bone situated at the back part of the nasal cavity between the maxilla and the pterygoid process of the sphenoid. ... The inferior nasal concha (Inferior Turbinated Bone) extends horizontally along the lateral wall of the nasal cavity [Fig. ... The vomer bone is one of the unpaired facial bones of the skull. ... The mandible (from Latin mandibŭla, jawbone) or inferior maxillary bone is, together with the maxilla, the largest and strongest bone of the face. ... The hyoid bone (Os Hyoideum; Lingual Bone) is a bone in the human neck, not articulated to any other bone; it is supported by the muscles of the neck and in turn supports the root of the tongue. ... The hyoid bone (Os Hyoideum; Lingual Bone) is a bone in the human neck, not articulated to any other bone; it is supported by the muscles of the neck and in turn supports the root of the tongue. ... The greater cornua project backward from the lateral borders of the body; they are flattened from above downward and diminish in size from before backward; each ends in a tubercle to which is fixed the lateral hyothyroid ligament. ... The hyoid bone (Lingual Bone) is a bone in the human neck, not articulated to any other bone; it is supported by the muscles of the neck and in turn supports the root of the tongue. ... The body of hyoid bone or central part is of a quadrilateral form. ... In humans, the upper limb is an anatomical term for the limb that is attached to the pectoral girdle. ... The pectoral girdle is the set of bones which connect the upper limb to the axial skeleton on each side. ... Collarbone and collar bone redirect here. ... Left scapula - front view () Left scapula - rear view () In anatomy, the scapula, or shoulder blade, is the bone that connects the humerus (arm bone) with the clavicle (collar bone). ... Look up ARM in Wiktionary, the free dictionary. ... The humerus is a long bone in the arm or fore-legs (animals) that runs from the shoulder to the elbow. ... The ulna (Elbow Bone) [Figs. ... The radius is the bone of the forearm that extends from the outside of your limb to your phlangx (lateral) of the elbow to the thumb side of the wrist. ... For other uses, see Hand (disambiguation). ... This article is about Carpal bones. ... The scaphoid bone (hand navicular) of the wrist is found on the thumb side of the hand, within the anatomical snuffbox. ... The lunate bone (os lunatum; semilunar bone) is a bone in the human hand that may be distinguished by its deep concavity and crescentic outline. ... The triquetral bone (also called triquetral, os triquetrum, cuneiform bone, pyramidal bone, cubital bone, os pyramidale, os triangulare, three-cornered bone, and triangular bone) is a type of carpal bone. ... The left pisiform bone. ... The trapezium is a bone in the human hand. ... In human anatomy, the trapezoid bone (lesser multangular bone; os multangulum minus) is a bone in the hands. ... The capitate bone (os capitatum; os magnum) is a bone in the human hand. ... The hamate bone (os hamatum; unciform bone) is a bone in the human hand that may be readily distinguished by its wedge-shaped form, and the hook-like process which projects from its volar surface. ... The metacarpus is the intermediate part of the hand skeleton that is located between the fingers distally and the carpus which forms the connection to the forearm. ... Proximal phalanges are bones found in the limbs of most vertebrates. ... Intermediate phalanges are bones found in the limbs of most vertebrates. ... Distal phalanges are bones found in the limbs of most vertebrate skeletons. ... In humans, the lower limb is an anatomical term for the limb that is attached to the pelvic girlde, what is commonly referred to as the leg. ... Human male pelvis, viewed from front Human female pelvis, viewed from front The pelvis is the bony structure located at the base of the spine (properly known as the caudal end). ... The pelvis (pl. ... The ilium of the pelvis is divisible into two parts, the body and the ala; the separation is indicated on the internal surface by a curved line, the arcuate line, and on the external surface by the margin of the acetabulum. ... Human male pelvis, viewed from front Human female pelvis, viewed from front The pelvis is the bony structure located at the base of the spine (properly known as the caudal end). ... The pubis, the anterior part of the hip bone, is divisible into a body, a superior and an inferior ramus. ... Diagram of an insect leg A leg is the part of an animals body that supports the rest of the animal above the ground and is used for locomotion. ... The femur or thigh bone is the longest, most voluminous, and strongest bone of the mammalian bodies. ... For other uses, see Patella (disambiguation). ... For other uses see fibula (disambiguation) The fibula or calf bone is a bone placed on the lateral side of the tibia, with which it is connected above and below. ... This article is about the vertebrate bone. ... For other uses, see Foot (disambiguation). ... FIG. 268– Bones of the right foot. ... The calcaneus is the large bone making up the heel of the human foot. ... See talus for other meanings of the word The talus bone or astragalus of the ankle joint connects the leg to the foot. ... The navicular bone occurs in human and horse anatomy. ... There are three cuneiform bones in the human foot: the medial cuneiform, the intermediate cuneiform and the lateral cuneiform. ... The cuboid bone is one of seven Tarsal bones. ... The metatarsus consists of the five long bones of the foot, which are numbered from the medial side (ossa metatarsalia I.-V.); each presents for examination a body and two extremities. ... Proximal phalanges are bones found in the limbs of most vertebrates. ... Intermediate phalanges are bones found in the limbs of most vertebrates. ... Distal phalanges are bones found in the limbs of most vertebrate skeletons. ... The malleus is 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. ... This article refers to a bone in the mammalian ear. ... The stapes or stirrup is the stirrup-shaped small bone or ossicle in the middle ear which attaches the incus to the fenestra ovalis, the oval window which is adjacent to the vestibule of the inner ear. ...


  Results from FactBites:
 
Ossicles - Wikipedia, the free encyclopedia (408 words)
The ossicles are, in order from the eardrum to the inner ear, the hammer, anvil, and stirrup, so named because of the shape of the bones.
The ossicles give the eardrum mechanical advantage via lever action and a reduction in the area of force distribution; the resulting vibrations would be much smaller if the sound waves were transmitted directly from the outer ear to the oval window.
It is believed that these muscles can contract to dampen 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 reduing the transmission of low frequencies (theory 2) (see acoustic reflex).
  More results at FactBites »

 
 

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