Where are the auditory ossicles located? Auditory ossicles: general structure

Auditory ossicles * (ossicula auditiva) - are located in the cavity of the middle ear of vertebrates and morphologically represent parts of the visceral skeleton (see. Vertebrates). Amphibians, reptiles and birds have only one bone, corresponding to the stirrup (stapes) and called columella auris. In mammals, in particular in humans, there are 3 main bones: The malleus (malleus), which consists of a head and a handle bearing two processes, short and long, and tightly connected to the eardrum.

Attached to a long process is a very important muscle(m. laxator tympani), which serves to loosen the tension of the eardrum (see Hearing), and to the short one - another important muscle that strains the membrane (m. tensor tympani). The second bone - the anvil (inxus) - really has the shape of an anvil, consisting of a body equipped with two processes: a short one attached to the tympanic membrane by means of a ligament, and a long one, which at the end is equipped with an apophysis, sometimes considered independent (the so-called lenticular) bone (ossiculum lenticulare Sylvii). This bone is adjacent to the 3rd bone - the stirrup, and the outer surface of the body of the anvil has a recess into which it receives the head of the malleus. The stirrup (stapes) consists of a head, which articulates with the lenticular bone, and two curved arches (crura) extending from the head, limiting the space covered with a special membrane (membrana propr ia stapidis) and abutting against the third component of the stirrup - into the footboard, locking the oval labyrinth window. Columella auris is usually a shelf-shaped bone, resting at one end against the tympanic membrane, and at the other against the oval window. In many lower mammals, the stirrup has the same column shape, but in higher ones, instead of a column, we have two knees, between which an artery passes, which, however, only in a few mammals (rodents, insectivores) remains for life, and in most, including number in humans disappears.

Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron. - St. Petersburg: Brockhaus-Efron. 1890-1907 .

See what "Ear ossicles*" are in other dictionaries:

BONS, a complex of small ossicles in the middle ear of most mammals. The auditory ossicles are the malleus, anvil, and stirrup. Vibrations of the tympanic membrane (in the tympanic cavity) are caught by the hammer, amplified ... ... Scientific and technical encyclopedic dictionary

HEARING BONES- See ossicles, auditory ...

- (ossicula auditiva) are located in the middle ear cavity of vertebrates and morphologically represent parts of the visceral skeleton (see Vertebrates). Amphibians, reptiles and birds have only one bone, corresponding to the stirrup (stapes) and called ... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

auditory ossicles- Three miniature bones of the middle ear - the hammer, anvil and stirrup, involved in the transmission of sound pressure to the inner ear ... Psychology of sensations: a glossary

Auditory ossicles (ossicula auditis), right- hammer; malleus head; incus hammer joint; anvil; short leg of the anvil; long leg of the anvil; incus stirrup joint; stirrup; back leg of the stirrup; stirrup base; the front leg of the stirrup; handle... ... Atlas of human anatomy

- (ossicula auditus, PNA, BNA; ossicula tympani, JNA) see the list of anat. terms... Big Medical Dictionary

BONES, HEARING- A set of three small bones (hammer, anvil and stirrup) in the middle ear, which transmit the vibrations of the tympanum to the cochlea ... Explanatory Dictionary of Psychology

Middle ear- (auris media) (Fig. 287), which is also called the tympanic cavity (cavum tympani), is a sound-conducting system that includes several components. The eardrum (membrana tympani) (Fig. 287, 288) is located on ... ... Atlas of human anatomy

MIDDLE EAR- MIDDLE EAR. Phylogenesis. In the historical development of the auditory apparatus, at a certain stage, an auxiliary one begins to join the more ancient formation of the inner ear, the so-called. sound-conducting department, the deeper part of which is C ... Big Medical Encyclopedia

- (aurus media) part of the ear between the outer and inner ear, which performs a sound-conducting function. The middle ear is in temporal bone and consists of three interconnected air cavities. The main one is the tympanic cavity (cavum ... ... Medical Encyclopedia

The human ear is a unique organ that functions on a pair basis, which is located in the very depths of the temporal bone. The anatomy of its structure makes it possible to capture mechanical vibrations of the air, as well as to carry out their transmission through internal media, then transform the sound and transmit it to the brain centers.

According to anatomical structure, human ears can be divided into three parts, namely the outer, middle and inner.

Elements of the middle ear

Studying the structure of the middle part of the ear, you can see that it is divided into several constituent parts: tympanic cavity, ear tube and auditory ossicles. The last of these include the anvil, hammer and stirrup.

Middle ear malleus

This part of the auditory ossicles includes such elements as the neck and the handle. The head of the malleus is connected through the hammer joint to the structure of the body of the incus. And the handle of this malleus is connected with the eardrum by fusion with it. A special muscle is attached to the neck of the malleus, which stretches the eardrum.

Anvil

This element of the ear has at its disposal a length of six to seven millimeters, which consists of a special body and two legs with short and long dimensions. The one that is short has a lenticular process that fuses with the incus stirrup joint and with the head of the stirrup itself.

What else is included in the auditory ossicle of the middle ear?

Stirrup

The stirrup has a head, as well as front and rear legs with a part of the base. The stirrup muscle is attached to its back leg. The base of the stirrup itself is built into an oval-shaped window in the vestibule of the labyrinth. An annular ligament in the form of a membrane, which is located between the support base of the stirrup and the edge of the oval window, contributes to the mobility of this auditory element, which is ensured by the action of air waves directly on the tympanic membrane.

Anatomical description of the muscles attached to the bones

Two transverse striated muscles are attached to the auditory ossicles, which perform certain functions for transmitting sound vibrations.

One of them stretches the eardrum and originates at the walls of the muscular and tubal canals related to the temporal bone, and then it attaches to the neck of the malleus itself. The function of this tissue is to pull the handle of the malleus inward. Tension occurs to the side. At the same time, the tympanic membrane is tensioned and therefore it is, as it were, stretched and concave into the region of the middle ear region.

Another muscle of the stirrup originates in the thickness of the pyramidal elevation of the mastoid wall of the tympanic region and is attached to the foot of the stirrup located behind. Its function is to reduce and remove from the hole the base of the stirrup itself. During powerful oscillations of the auditory ossicles, along with the previous muscle, the auditory ossicles are held, which significantly reduces their displacement.

The auditory ossicles, which are interconnected by joints, and, in addition, the muscles related to the middle ear, fully regulate the movement of air currents on different levels intensity.

Tympanic cavity of the middle ear

In addition to the bones, a certain cavity is also included in the structure of the middle ear, which is commonly called the tympanic cavity. The cavity is located in the temporal part of the bone, and its volume is one cubic centimeter. In this area, the auditory ossicles are located with the eardrum nearby.

Above the cavity is located which consists of cells that carry air currents. It also contains a kind of cave, that is, a cell through which air molecules move. In the anatomy of the human ear, this area plays the role of the most characteristic landmark in the implementation of any surgical interventions. How the auditory ossicles are connected is of interest to many.

Eustachian tube in human middle ear structure anatomy

This area is a formation that can reach a length of three and a half centimeters, and the diameter of its lumen can be up to two millimeters. Its upper beginning is located in the tympanic region, and the lower pharyngeal mouth opens in the nasopharynx approximately at the level of the hard palate.

The auditory tube consists of two sections, which are separated by the narrowest point in its area, the so-called isthmus. The bone part departs from the tympanic region, which extends below the isthmus, it is commonly called membranous-cartilaginous.

The walls of the tube, located in the cartilaginous region, are usually closed at rest, but when chewing, they can open slightly, and this can also occur during swallowing or yawning. The increase in the lumen of the tube occurs through two muscles that are associated with the palatine curtain. The shell of the ear is lined with epithelium and has a mucous surface, and its cilia move towards the pharyngeal mouth, which makes it possible to ensure the drainage function of the tube.

Other facts about the auditory ossicle in the ear and the structure of the middle ear

The middle ear is directly connected to the nasopharynx through the Eustachian tube, whose primary function is to regulate pressure that comes from outside the air. A sharp laying of human ears can signal a transient decrease or increase in environmental pressure.

A long and prolonged soreness in the temples, most likely, indicates that the ears are currently trying to actively fight the infection that has arisen and thus protect the brain from all sorts of violations of its performance.

Internal auditory ossicle

Among the fascinating facts of pressure, one can also include reflex yawning, which signals that its environment has undergone sharp changes in the human environment, and therefore a reaction in the form of a yawn was caused. You should also know that the human middle ear contains a mucous membrane in its structure.

Do not forget that unexpected, exactly, as well as sharp sounds can provoke muscle contraction on a reflex basis and harm both the structure and the functioning of hearing. The functions of the auditory ossicles are unique.

All of these structures carry such a functionality of the auditory ossicles as the transmission of perceived noise, as well as its transfer from the outer region of the ear to the inner. Any violation and failure of the functioning of at least one of the buildings can lead to the destruction of the hearing organs completely.

Inflammation of the middle ear

The middle ear is a small cavity between the inner ear and the middle ear. The transformation of air vibrations into fluid vibrations is provided by the middle ear, which is recorded by auditory receptors in the inner ear. This happens with the help of special bones (hammer, anvil, stirrup) due to sound vibration from the eardrum to the auditory receptors. To equalize the pressure between the cavity and the environment, the middle ear communicates with the Eustachian tube with the nose. The infectious agent penetrates this anatomical structure and provokes inflammation - otitis media.

Auditory ossicles: Hammer, malleus; Anvil, incus; Stirrup, stapes. Functions of bones.

Located in tympanic cavity three small auditory ossicles are named after the malleus, anvil, and stirrup.

1. Hammer, malleus, equipped with a rounded head, caput mallei, which through necks, collum mallei, connects with handle, manubrium mallei.

2. Anvil, incus, has a body, corpus incudis, and two divergent processes, of which one is more short, crus breve, directed back and rests against the hole, and the other - long shoot, crus longum, runs parallel to the handle of the malleus medially and posteriorly from it and has a small oval thickening, processus lenticularis articulated with the stirrup.

3. stirrup, in its form justifies its name and consists of small head, caput stapedis, bearing the articular surface for processus lenticularis anvil and two legs: front, more straight, crus anterius, and back, more curved, crus posterius, which are connected with oval plate, basis stapedis inserted into the vestibule window.
In places of articulation of the auditory ossicles, two real joints with limited mobility: articulatio incudomallearis and articulatio incudostapedia. The stirrup plate is connected to the edges fenestra vestibuli through connective tissue, syndesmosis tympano-stapedia.

auditory ossicles reinforced, in addition, by several more separate ligaments. Generally all three auditory ossicles represent a more or less mobile chain running across the tympanic cavity from the tympanic membrane to the labyrinth. Bones mobility gradually decreases in the direction from the malleus to the stirrup, which protects the spiral organ located in the inner ear from excessive shaking and harsh sounds.

The chain of bones performs two functions:
1) bone conduction of sound and
2) mechanical transmission of sound vibrations to the oval window of the vestibule, fenestra vestibuli.

6.3.3. The structure and function of the middle ear

Middle ear(Fig. 51) represented by a system of air cavities in the thickness of the temporal bone and consists of tympanic cavity, auditory tube And mastoid process with his bone cells.

tympanic cavity - the central part of the middle ear, located between the tympanic membrane and the inner ear, is lined from the inside mucous membrane, filled with air. In shape, it resembles an irregular tetrahedral prism, with a volume of about 1 cm 3. The upper wall or roof of the tympanic cavity separates it from the cranial cavity. There are two openings in the inner bony wall that separates the middle ear from the inner ear: oval And round windows covered with elastic membranes.

The auditory ossicles are located in the tympanic cavity: hammer, anvil and stirrup(so called because of their shape), which are interconnected by joints, strengthened by ligaments and represent a system of levers. The handle of the malleus is woven into the center of the tympanic membrane, its head articulates with the body of the incus, and the anvil, in turn, articulates with the head of the stirrup with a long process. The base of the stirrup is included in oval window(as in a frame), connecting to the edge through the ring connection of the stirrup. The bones are covered with a mucous membrane on the outside.

Function auditory ossicles transmission of sound vibrations from the tympanic membrane to the oval window of the vestibule and their gain, which allows you to overcome the resistance of the membrane of the oval window and transmit vibrations to the perilymph of the inner ear. This is facilitated by the lever articulation of the auditory ossicles, as well as the difference in the area of ​​the tympanic membrane (70 - 90 mm 2) and the area of ​​​​the membrane of the oval window (3.2 mm 2). The ratio of the surface of the stirrup to the tympanic membrane is 1:22, which increases the pressure of sound waves on the membrane of the oval window by the same amount. This pressurization mechanism is an extremely useful device for efficient transmission of acoustic energy from the air in the middle ear to the fluid-filled cavity of the inner ear. Therefore, even weak sound waves can cause an auditory sensation.

The middle ear has two muscles(the smallest muscles in the body), attached to the handle of the malleus (a muscle that strains the eardrum) and the head of the stirrup (stapedius muscle), they support the auditory ossicles in weight, regulate their movements, providing accommodation of the hearing aid to sounds of different strengths and heights.

For the normal functioning of the tympanic membrane and the ossicular chain, it is necessary that air pressure on either side of the eardrum(in the external auditory canal and tympanic cavity) was the same. This function is performed auditory (Eustachian) pipe- a canal (about 3.5 cm long, about 2 mm wide) connecting the tympanic cavity of the middle ear with the nasopharyngeal cavity (Fig. 51). From the inside, it is lined with a mucous membrane with ciliated epithelium, the movement of the cilia of which is directed towards the nasopharynx. The part of the tube adjacent to the tympanic cavity has bony walls, and the part of the tube adjacent to the nasopharynx is the cartilaginous walls, which usually come into contact with each other, but when swallowing, yawning, due to the contraction of the pharyngeal muscles, diverge to the sides and air from the nasopharynx enters the tympanic cavity. This maintains the same air pressure on the eardrum from the external auditory canal and the tympanic cavity.

Mastoid - a process of the temporal bone (shaped like a nipple), located behind the auricle. In the thickness of the process there are cavities - cells filled with air and communicating with each other through narrow slits. They improve the acoustic properties of the middle ear.

Rice. 51. The structure of the middle ear:

4 - hammer, 5 - anvil, 6 - stirrup; 7 - auditory tube

Inner Fish [History human body from ancient times to the present day] Shubin Nil

Middle ear - three auditory ossicles

Mammals are special creatures. Hair and mammary glands distinguish us mammals from all other living organisms. But many will be surprised to learn that the structures located deep in the ear are also important distinguishing features of mammals. No other animal has bones like those in our middle ear: mammals have three of these bones, while amphibians and reptiles have only one. Fish don't have these bones at all. How, then, did the bones of our middle ear come about?

A bit of anatomy: let me remind you that these three bones are called the hammer, anvil and stirrup. As already mentioned, they develop from the gill arches: the hammer and anvil - from the first arch, and the stirrup - from the second. This is where our story begins.

In 1837, German anatomist Karl Reichert studied mammalian and reptile embryos to understand how the skull is formed. He traced the development of gill arch structures different types to understand where they end up in the skulls of different animals. The result of lengthy research was a very strange conclusion: two of the three auditory ossicles of mammals correspond to fragments of the lower jaw of reptiles. Reichert couldn't believe his eyes! Describing this discovery in his monograph, he did not hide his surprise and delight. When he comes to comparing the auditory ossicles with the bones of the jaw, the usual dry style of 19th-century anatomical descriptions gives way to a much more emotional style, showing how startled Reichert was by this discovery. From his results, the inevitable conclusion followed: the same gill arch, which forms part of the jaw in reptiles, forms the auditory ossicles in mammals. Reichert advanced the thesis, which he himself had difficulty believing, that the structures of the mammalian middle ear corresponded to the structures of the jaw of reptiles. The situation will look more complicated if we remember that Reichert came to this conclusion more than twenty years earlier than Darwin's position on a single genealogical tree of all living things sounded (this happened in 1859). What is the point of saying that different structures in two different groups of animals "correspond" to each other, without a concept of evolution?

Much later, in 1910 and 1912, another German anatomist, Ernst Gaupp, continued Reichert's work and published the results of his exhaustive research on the embryology of the mammalian hearing organs. Gaupp provided more details and, given the time he worked, was able to interpret Reichert's discovery in terms of evolution. Here's what he came up with: the three ossicles in the middle ear show a connection between reptiles and mammals. The single bone of the middle ear of reptiles corresponds to the stapes of mammals - both of which develop from the second gill arch. But the truly stunning discovery was not that, but that the other two bones in the mammalian middle ear, the malleus and anvil, developed from bones located at the back of the reptile jaw. If this is true, then the fossil record should show how the ossicles passed from the jaw to the middle ear during the emergence of mammals. But Gaupp, unfortunately, studied only modern animals and was not ready to fully appreciate the role that fossils could play in his theory.

Since the forties of the 19th century, fossil remains of animals of a previously unknown group began to be mined in South Africa and Russia. Many well-preserved finds were found - whole skeletons of creatures the size of a dog. Shortly after these skeletons were discovered, many of their specimens were boxed and sent to London for identification and study by Richard Owen. Owen found that these creatures had a striking mixture of features from different animals. Some structures of their skeletons resembled reptiles. At the same time, others, especially the teeth, were more like those of mammals. And these were not isolated finds. In many localities, these mammal-like reptiles were the most abundant fossils. They were not only numerous, but also quite diverse. Already after Owen's research, such reptiles were also found in other regions of the Earth, in several layers of rocks corresponding to different periods of earth's history. These findings formed a beautiful transitional series leading from reptiles to mammals.

Until 1913, embryologists and paleontologists worked in isolation from each other. But this year was significant in that the American paleontologist William King Gregory, of the American Museum of Natural History in New York, drew attention to the connection between the embryos in which Gaupp worked and the fossils found in Africa. The most "reptilian" of all mammal-like reptiles had only one bone in the middle ear, and its jaw, like other reptiles, consisted of several bones. But in studying a series of reptiles that were increasingly close to mammals, Gregory discovered something very remarkable - something that would have deeply struck Reichert if he were alive: a consistent series of forms, unambiguously indicating that the bones of the back of the jaw in mammalian reptiles gradually decreased and shifted, until, finally, in their descendants, mammals, they took their place in the middle ear. The hammer and anvil actually evolved from the bones of the jaw! What Reichert discovered in embryos had long since been buried in the earth as a fossil, waiting for its discoverer.

Why do mammals need to have three bones in the middle ear? The system of these three bones allows us to hear sounds of a higher frequency than those animals that have only one bone in the middle ear are able to hear. The emergence of mammals was associated with the development of not only bite, which we discussed in the fourth chapter, but also more acute hearing. Moreover, it was not the appearance of new bones that helped to improve the hearing of mammals, but the adaptation of old ones to perform new functions. Bones that originally served to help reptiles bite are now helping mammals hear.

This is where the hammer and anvil come from. But where, in turn, did the stirrup come from?

If I were to just show you how an adult human and a shark are built, you would never guess that this tiny bone in the back of the human ear corresponds to a large cartilage in upper jaw sea ​​predator. However, studying the development of man and sharks, we are convinced that this is exactly the case. The stirrup is a modified skeletal structure of the second branchial arch, like this shark cartilage, which is called the suspension, or hyomandibular. But pendants are not a middle ear bone, because sharks do not have ears. In our aquatic relatives, the cartilaginous and bony fishes, this structure links the upper jaw to the skull. Despite the obvious difference in the structure and functions of the stapes and pendant, their relationship is manifested not only in a similar origin, but also in the fact that they are served by the same nerves. The main nerve leading to both of these structures is the nerve of the second arch, i.e. facial nerve. So, we have a case where two completely different skeletal structures have a similar origin in the development of the embryo and a similar system of innervation. How can this be explained?

And again, we should turn to fossils. If we trace the changes in the suspension from cartilaginous fishes to creatures like Tiktaalik, and further to amphibians, we see that it gradually decreases and finally separates from the upper jaw and becomes part of the hearing organ. At the same time, the name of this structure also changes: when it is large and supports the jaw, it is called a pendant, and when it is small and participates in the work of the ear, it is called a stirrup. The transition from suspension to stirrup took place when the fish came out onto land. To hear in the water, you need completely different organs than on land. small size and the position of the stirrup is the best possible way to capture the small vibrations occurring in the air. And this structure arose due to a modification of the structure of the upper jaw.

We can trace the origin of our auditory ossicles from the skeletal structures of the first and second gill arches. The history of the hammer and anvil (left) is shown from ancient reptiles, and the history of the stirrup (right) from even older cartilaginous fish.

Our middle ear holds traces of two of the most important changes in the history of life on Earth. The emergence of the stirrup - its development from the suspension of the upper jaw - was caused by the transition of fish to life on land. In turn, the malleus and anvil arose during the transformation of ancient reptiles, in which these structures were part of the lower jaw, into mammals, which they help to hear.

Let's look deeper into the ear - the inner ear.