Muscles of the tympanic membrane. Muscle straining the eardrum
The muscle straining the tympanic membrane (m. Tensor tympani, PNA, BNA, JNA) see the list of anat. terms 837.
Large Medical Dictionary. 2000 .
See what the "tympanic membrane" muscle is in other dictionaries:
- (aurus media) the part of the ear between the outer and inner earperforming a sound-conducting function. The middle ear is in temporal bone and consists of three interconnected air cavities. The main is the tympanic cavity (cavum ... ... Medical encyclopedia
S. has a special function of the ear, excited by vibrating bodies in the air or water. IN hearing aid we are dealing with the nerve of a special feeling, auditory nerve; with end organs adapted to the perception of sound ... encyclopedic Dictionary F. Brockhaus and I.A. Efron
S. has a special function of the ear, excited by vibrating bodies in the ambient air or water. In the hearing aid we deal with the nerve of the special sense, the auditory nerve; with finite organs adapted to the perception of sound ... ... Encyclopedia of Brockhaus and Efron
middle ear - (auris media) a part of the vestibular cochlear organ located in the pyramid of the temporal bone and consisting of the tympanic cavity, auditory tube and cells of the mastoid process. The central position in the middle ear is occupied by the tympanic cavity, which ... Glossary of terms and concepts in human anatomy
MUSCLES - MUSCLES. I. Histology. General morphodogically, the tissue of the contractile substance is characterized by the presence of differentiation in the protoplasm of its specific elements. fibrillar structure; the latter are spatially oriented in the direction of their reduction and ... ... Big medical encyclopedia
muscle straining the eardrum - (m. tensor tympani, PNA, BNA, JNA) see the list of anat. terms 837 ... Large Medical Dictionary
Middle ear - (aurus media) part of the ear between the outer and inner ear that performs a sound-conducting function. The middle ear is located in the temporal bone and consists of three air cavities communicating with each other. The main is the tympanic cavity (cavum ... ... Medical encyclopedia
Hearing - S. has a special function of the ear, excited by vibrating bodies in the surrounding air or water. In the hearing aid we are dealing with a nerve of a special sense, the auditory nerve; with end organs adapted to the perception of sound ... Encyclopedic Dictionary of F.A. Brockhaus and I.A. Efron
Hearing - S. has a special function of the ear, excited by vibrating bodies in the ambient air or water. In the hearing aid we deal with the nerve of the special sense, the auditory nerve; with finite organs adapted to the perception of sound ... ... Encyclopedia of Brockhaus and Efron
middle ear - (auris media) part of the vestibular cochlear organ, located in the pyramid of the temporal bone and consisting of the tympanic cavity, auditory tube and cells of the mastoid process. The central position in the middle ear is occupied by the tympanic cavity, which ... Glossary of terms and concepts in human anatomy
MUSCLES - MUSCLES. I. Histology. General morphodogically, the tissue of the contractile substance is characterized by the presence of differentiation in the protoplasm of its specific elements. fibrillar structure; the latter are spatially oriented in the direction of their reduction and ... ... Big medical encyclopedia
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The inner wall of the tympanic cavity is the most complex in comparison with other formations of the middle ear. It contains two holes - the window of the snail (fenestra cochleae) and the window of the vestibule (fenestra vestibuli), as well as a bulge - the promontorium (Fig. 4). The window of the vestibule is behind and above the cape, the window of the snail is behind and below the promontory. closed by the base of the stirrup, the window of the cochlea - by a fibrous membrane (secondary tympanic membrane).
Figure: 4. Schematic representation of the middle ear: 1 - roof of the tympanic cavity; 2 - entrance to the cave; 3 - protrusion of the lateral semicircular canal; 4 - bony canal of the facial nerve; 5 - window of the vestibule; 6 - snail window; 7 - jugular vein; 8 - tympanic membrane; 9 - auditory tube; 10 - cape
Above the window of the vestibule there is a horizontal knee of the bony canal of the facial nerve, and above and behind - the ampulla of the horizontal semicircular canal. The facial nerve bends from the front to the back of the protrusion of the horizontal semicircular canal, goes down, forming a descending knee, and through the styloid opening (foramen stylomastoideum) leaves the skull, dividing into a series of terminal branches, the so-called goose foot (pes anserinus). It is important for an otosurgeon to remember these anatomical structures, since their damage can be accompanied by the development of paresis or paralysis of the facial nerve and intralabyrinth complications.
In the lower part of the tympanic cavity, the tympanic string (chorda tympani), which has taste and salivary fibers, emerges from the bone canal, separating from the facial canal. The fibers are placed between the auditory ossicles (malleus and incus), pass through the entire tympanic cavity, heading to the tongue, submandibular and sublingual glands.
The external auditory canal and the middle ear are separated by the tympanic membrane (membrana tympani), the thickness of which is about 0.1 mm, the shape approaches a circle, and the diameter is about 1 cm.On the outside, the tympanic membrane is covered with epidermis, with a mucous membrane on the inside. Between the epidermis and the mucous membrane on the tympanic membrane, there is a connective tissue layer with radial and circular elastic fibers that provide tension to the tympanic membrane. The eardrum is located obliquely in the external auditory canal, its top part tilted outward. central part the tympanic membrane is concave inward, due to its fusion with the handle of the hammer. The area where the hammer handle ends is called the umbo membranae tympani and corresponds to the maximum retraction of the tympanic membrane into the middle ear cavity.
The tympanic membrane consists of two parts: stretched (pars tensa) and relaxed (pars flaccida). The relaxed part is housed in upper section the tympanic membrane, it has an insignificant size, there is no fibrous layer in it; the stretched part is large and located in the center and below. Due to the conical shape and unequal tension in different areas, the eardrum has a slight intrinsic resonance and transmits acoustic signals of different frequencies with the same strength. The eardrum is conventionally subdivided into four quadrants: anteroposterior, antero-inferior, posterior superior, posterior inferior (Fig. 5).
Figure: 5. Eardrum: 1 - posterior superior quadrant; 2 - anteroposterior quadrant; 3 - posterior lower quadrant; 4 - anteroinferior quadrant; 5 - lateral process of the malleus; 6 - light cone; 7 - hammer handle
Quadrants are formed by two mutually perpendicular lines. This conditional division of the tympanic membrane is taken to indicate the location of the localization of scars, perforations and other pathological formations on its surface. The center of the tympanic membrane is located at a distance of 1.5-2 mm from the medial wall of the tympanic cavity; in the area of \u200b\u200bthe anteroinferior quadrant, it lags behind by 4-5 mm, in the area of \u200b\u200bthe posterior inferior quadrant - up to 6 mm from the inner wall of the tympanic cavity.
As a result of such anatomical and topographic features of the placement of the tympanic membrane, many clinicians with inflammation of the middle ear carry out its paracentesis in the area farthest from the medial wall of the tympanic cavity - in the posterior inferior quadrant. The eardrum, when illuminated by a frontal reflector, forms a reflection in the form of a light triangle in the antero-inferior quadrant, called the light cone. The handle of the hammer and its short process are interwoven into the eardrum along the radius.
The color of the tympanic membrane under natural light is ash-gray, under electric light it is yellowish-gray. During an otoscopy, the light cone, the handle, and the short process of the malleus can normally be seen. These landmarks are the identification marks of the eardrum. Under the condition of the development of pathological processes in the middle ear cavity, deformation or retraction of the tympanic membrane, the light reflex may disappear, and the characteristics of other identification marks also change.
In clinical practice, the tympanic cavity is conventionally subdivided into three floors: the upper - the tympanic space, or attic (epitympanum), the middle (mesotympanum) and the lower (hypotympanum). The epitympanum is located above the short process of the malleus, the mesotympanum is located between the short process of the malleus and bottom wall external auditory canal (the level corresponds to the stretched part of the tympanic membrane), the hypotympanum is a small depression located below the level of attachment of the tympanic membrane.
The ear bones, ligaments, muscles, nerves and blood vessels are located in the tympanic cavity. The auditory ossicles (Fig. 6) include the malleus, incus, and stapes.
Figure: 6. Auditory bones: 1 - malleus; 2 - anvil; 3 - stirrup
In the hammer, a head, a neck, a lateral process and a handle are distinguished. The malleus is tightly fixed by the handle to the eardrum, and its head is connected to the incus by means of a joint and tendon. In the incus, a body, long and short legs and a lenticular process are distinguished. With its long process, the incus attaches to the head of the stirrup. The stirrup is the smallest bone in the human body. It distinguishes between head, neck, front and back legs and base.
The base of the stirrup is fixed in the window of the vestibule with a ring ligament. The auditory ossicles are closely connected with the eardrum, the window of the vestibule, and also with each other, forming a single movable chain that transmits the vibration of the eardrum to the receptor structures of the inner ear.
In the middle ear cavity there are also two miniature muscles - the muscle that strains the tympanic membrane (m. Tensor tympani) and the stapedius muscle (i.e. stapedius). The muscle that strains the eardrum starts from the anterior wall of the tympanic cavity, where it attaches to the bony semicircular canal. Passing through the tympanic cavity, the muscle turns into a tendon and is woven into the handle of the hammer. Its innervation is carried out by fibers trigeminal nerve (V pair of cranial nerves).
The contraction of the muscle straining the tympanic membrane is accompanied by the movement of the hammer handle inward, which leads to the pressing of the stapes into the oval window. The stapes muscle originates from the posterior wall of the tympanic cavity and attaches to the head of the stapes. When it contracts, the base of the stapes extends from the vestibule window into the tympanic cavity. The stapes muscle is innervated by a branch of the facial nerve (VII pair).
The walls of the tympanic cavity and all of its formations are lined with a mucous membrane.
The middle ear cavity connects to the environment through the auditory tube. The auditory tube is a narrow canal 30-38 mm long, which begins in the anterior wall of the tympanic cavity and ends with the tympanic opening in the cavity of the nasal part of the pharynx at the level of the posterior end of the inferior turbinate. Anatomically distinguish between the bone and cartilaginous parts of the auditory tube. The site of transition from one part to another is called the isthmus tubae auditivae.
This is the narrowest part of the auditory tube, and most often it is here that its blockage occurs. The lumen of the tube in the bone part is round, in the cartilaginous part it is slit-like. A muscle is attached to the cartilaginous part, straining the soft palate (i.e. tensor veli palatini). From the place of its attachment, the muscle goes down, turns into a tendon and ends in the aponeurosis of the soft palate. When swallowing and yawning, the muscle contracts, pulls the cartilaginous part of the tube and opens the pharyngeal opening of the auditory tube.
Other muscles also take part in the expansion of the opening of the auditory tube - the muscle that lifts palatine curtain (i.e. levator veli palatini), and palatopharyngeal muscle (i.e. palatopharyngeus). Periodic opening of the auditory tube allows air to flow into the tympanic cavity and equalizes the pressure in it with the ambient air pressure. The auditory tube is covered with mucous membrane. Its epithelium in the cartilaginous part is ciliated, multi-row, the movement of the cilia is directed towards the nasal part, which contributes to the evacuation of secretions from the tympanic cavity into the nasal part of the pharynx. In children, the auditory tube is located more horizontally, it is relatively wider and shorter, its pharyngeal opening is gaping, which predetermines a more rapid spread of infection from the nasal cavity to the ear.
Mastoid process (processus mastoideus), located behind auricle, represents bone tissuecontaining air-filled cells, cells. In shape, the process resembles a cone-shaped formation with the top down. The mucous membrane lining the cave and process cells is a continuation of the mucous membrane of the tympanic cavity. The cells are connected to each other, as well as to the tympanic cavity. The largest cell is called a cave (antrum mastoideum), it is round, the size of a pea. The baby has this cell from birth.
The upper wall of the cave is a continuation of the roof of the tympanic cavity, separating the tympanic cavity and the cave from the middle cranial fossa. When the upper wall of the cave is destroyed by a purulent process, inflammation from the middle ear can go directly to the lining of the brain. On the inner surface of the mastoid there is a depression in which the sigmoid venous sinus is located, which carries out the outflow of blood from the brain to the jugular vein.
DI. Zabolotny, Yu.V. Mitin, S.B. Bezhapochny, Yu.V. Deeva
The middle ear contains two muscles that attach to the ossicular chain — the muscle that contracts the eardrum and the stapes.
Stapes muscle(M. stapedius) is the smallest in the body: its average length is 6.3 mm, and its cross-sectional area is 4.9 mm 2. The muscle is completely enclosed in a pyramidal protrusion (eminentia pyramidalis) on the back wall of the tympanic cavity and originates from the walls of its own canal. Its tendon exits through the apex of the pyramidal protrusion and then goes horizontally until it is attached to the posterior surface of the stapes neck. Thus, during its contraction, the stapes muscle pulls the stapes back. The stapedius muscle is innervated by the stapedius branch VII ( facial) the cranial nerve extending from it directly near the muscle itself.
Muscle straining the eardrum(M. tensor tympani) is located in the bony semi-canal directly above the auditory tube, from which it is separated by a thin bony septum. The muscle starts from the cartilage of the auditory tube, from the walls of its own canal, a part of the main bone adjacent to the wall of the canal. When leaving the canal, the tendon of this muscle makes a turn around a small hook-shaped protrusion on the promontorium (processus cochleariformis), crosses the tympanic cavity in the lateral direction and attaches to the apex of the handle or neck of the malleus. With the contraction of the muscle that strains the eardrum, the handle of the hammer is displaced anteriorly and inward. This muscle is innervated by the eponymous branch of the mandibular nerve (3rd branch V - trigeminal- cranial nerve), the fibers of which pass through the ganglion oticum.
Both intra-tympanic muscles are completely enclosed in bone canals and are connected to the chain of the auditory ossicles by the corresponding tendons. This, according to G. von Bekesy, allows you to avoid distortions of sound that occur during muscle contractions. Histological examination of the muscles of the middle ear revealed both striated and smooth fibers. This is not surprising, since these muscles, which function involuntarily during sound stimulation, can contract at will in some people.
Certain muscles are known to contract in response to sound. Reflex contraction of the auricle muscles, for example, is called pinna reflex. Preyer (1879) studied this phenomenon in detail in rodents. Much more important are the contractions of the muscles of the tympanic cavity in response to sound stimuli. For the first time, bilateral contraction of the muscle that strains the eardrum, when exposed to one ear with high intensity sound, was discovered in the late 19th century during experiments on dogs. Later (in the early 20th century) it was shown that the stapes muscle in cats and rabbits also responds to intense sound stimulation.
The first contraction of the stapes muscle in humans was observed through a perforated eardrum by Luscher in 1929. Politzer, Cobrack, Lindsay, Lorente de No, Philip, Hallpike and other famous scientists were also studying the acoustic reflex.
Contraction of the tympanic muscles in response to intensivesoundstimulation is called acoustic (muscle) reflex- AR. It is unconditional.
, m. tensor tympani... It takes place in the half-channel of the same name above the auditory tube. Its tendon surrounds the cochlear process, bends almost at right angles laterally, and attaches to the base of the malleus handle. Inn .: mandibular nerve. Figure: AND.Stapes muscle
, m. stapedius... It starts in the bony canal on the posterior wall of the tympanic cavity, its tendon exits through the opening at the apex of the pyramidal eminence and attaches to the head of the stapes. With muscle contraction, the base of the stirrup is pressed more tightly against the window of the vestibule, which contributes to attenuation sound wavereaching the inner ear. Inn .: stapedal nerve (branch n. Facialis). Figure: B.The mucous membrane of the tympanic cavity
, tunica mucosa cavitatis tympanicae... Consists of a single-layer flat (cubic) epithelium and a thin lamina propria containing a large number of blood vessels.Posterior hammer fold
, plica mallearis posterior... It runs from the base of the hammer handle back to the top of the drum ring. Contains a portion of a drum string. Figure: D.Anterior hammer fold
, plica mallearis anterior... It runs from the base of the hammer handle forward to the top of the drum ring. Contains the anterior part of the drum string, the anterior process of the hammer and lig. mallei anterius. Figure: D.Drum string fold
, plica chordae tympani... Connects the hammer folds in the neck of the malleus. Figure: D.7a.
Deepening of the tympanic membrane
, recessus membranae tympanicae... Pockets of the tympanic mucosa.Anterior groove [tympanic membrane]
, recessus anterior... Located between the anterior hammer fold and the tympanic membrane. Figure: D.Upper recess [tympanic membrane] [[pocket of the Prussian]]
, recessus superior []... From the lateral side, it is limited by the loose part of the membrane, from the medial side - by the head and neck of the malleus, as well as by the body of the incus. Figure: D.10.
Posterior groove [tympanic membrane]
, recessus posterior... Located between the posterior hammer fold and the tympanic membrane. Figure: D.11.
Anvil fold
, plica incudialis... It passes between the dome of the tympanic cavity and the head of the anvil, or connects the short stem of the incus with the back wall of the tympanic cavity. Figure: D.12.
Stirrup fold
, plica stapedialis... Located between the posterior wall of the tympanic cavity and the stirrup, covering m. stapedius and stirrup. Figure: B.13.
Auditory tube
, tuba auditoria (auditiva)... Bone-cartilaginous tube, about 4 cm long between the middle ear and the nasopharynx. Serves for the entry of air into the tympanic cavity. Figure: AND , Figure: IN.14.
The tympanic opening of the auditory tube
, ostium tympanicum tubae auditоriae... It is located on the anterior wall of the tympanic cavity, slightly above its bottom. Figure: AND.15.
Bony part of the auditory tube
, pars ossea tubae auditoriae... Its posterolateral (upper) part is approximately 1/3 of its entire length. It is located downward from the semicanal of the muscle straining the tympanic membrane, and ends with an opening located between the carotid canal and the foramen spinosum. Figure: AND.16.
Isthmus of the auditory tube
, isthmus... Narrowing at the junction of the cartilaginous part of the tube into the bone. Figure: AND.17.