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The outer ear, auris externa, consists of the auricle and the external auditory meatus.
The auricle, auricula, (Fig. 1.1.1), basically has a complex form of elastic cartilago-cartilago auriculae, covered with skin. There is no cartilage in the lower third. A fold of skin filled with adipose tissue forms the ear lobule, lobulus auriculae, (lobe). With inflammation of the cartilage of the auricle (perichondritis) hyperemia does not extend to the earlobe.
The free edge of the shell is wrapped on its concave side, forming a curl, helix. The front end of the curl, located above the external auditory canal, is called the curl leg, crus helicis. In parallel with the curl on the concave side of the shell, there is a second elevation - the antihelix, antehelix. Upward, the antihelix differs into two legs - crura antehelicis, which limit the shallow triangular fossa, fossa triangularis. The curl and anti-curl are separated from each other by a groove, the so-called rook, scapha. In front of the anti-helix is an ear-shell recess, concha auriculae, which is divided into the upper part, called the shell shuttle, cyrnba conchae, and the lower, called the shell cavity, cavum conchae. At the bottom of the latter there is an opening of the external auditory meatus. In front, the shell cavity is bounded by a clearly defined protrusion - the tragus, tragus. Behind, at the lower end of the anti-helix, opposite the tragus, is a similar tubercle-antitragus, antitragus. The tragus and anti-tragus are separated by an interstitial notch, incisura intertragica.
The ear muscles in humans are poorly developed, they are almost not subject to arbitrary contraction. Distinguish between the front, upper and lower ear muscles.
The external auditory meatus, meatus acusticus externus (Fig. 1.1.1), begins with an opening at the bottom of the shell cavity and consists of the outer cartilaginous part, meatus acusticus externus cartilagineus and the internal bone, meatus acusticus externus osseus. The passage from the middle ear cavity is fenced off by the eardrum.
The dimensions of the external auditory meatus vary. Its average length in an adult is 2.5 cm, with 1/3 in the cartilage and 2/3 in the bone. The clearance of the passage is elliptical in shape with a diameter of 6-9 mm. Its diameter gradually decreases to the junction of the cartilaginous part with the bony part, forming an isthmus, then it grows and again narrows at the tympanic membrane.
Between the bony and cartilage sections of the external auditory meatus, an angle is formed that is open anteriorly and downward. In this regard, with otoscopy, in adults, it is necessary to delay the auricle posteriorly and upward. In young children, the external auditory meatus is more direct, the eardrum is located horizontally, therefore, for a better view during otoscopy, it is necessary to pull the auricle posteriorly and downward. The cartilage of the auditory meatus, cartilago meatus acustici, is integral with the cartilage of the auricle and has the shape of an irregular quadrangular plate curved in the form of a groove. The cartilaginous groove, in its entirety, is interrupted by vertical incisions of the cartilage of the auditory meatus, the so-called Santorinium cracks, incisurae cartilaginis meatus acustici (Santorini), filled with fibrous tissue. Through these gaps, an infection from the ear canal can spread to the capsule of the temporomandibular joint and the parotid salivary gland or vice versa.
The cartilaginous part of the ear canal is lined with thin skin, in which there is hair, sebaceous and special sulfur glands, which are modified sweat glands. Hair protects the external auditory area from dust particles. Sulfur glands secrete earwax and are called ceruminous glandulae ceruminosae.
Earwax is an anti-inflammatory agent that prevents the development of inflammation of the skin of the ear canal, which is in conditions of constant temperature and humidity, which is necessary for normal transmission of the sound wave. Excess earwax leads to the formation of sulfur plugs. Subcutaneous tissue in the membranous region is quite pronounced, the presence of hair makes it possible for a boil and ostiofolliculitis to occur. In the area of the bony auditory canal, the skin is devoid of hair and glands. It is closely associated with the periosteum, gradually becoming thinner and passes to the eardrum only in the form of the epidermis. Therefore, sulfuric plugs, boils do not form in the bone section of the auditory meatus. Due to the close connection of the skin lining with the periosteum, inflammatory processes in the bone section of the external auditory canal are painful.
The bony part of the auditory meatus is formed by the drum section of the temporal bone. The upper wall consists of two plates of temporal bone scales. The upper, shorter plate faces the cavity of the middle cranial fossa, and the lower one into the auditory meatus. Carious processes of the upper wall can spread to the cranial cavity. A fracture of the base of the skull in this place is often accompanied by bleeding with cerebrospinal fluid from the ear canal. The posterior wall separates the passage from the cells of the mastoid process. When mastoid inflammation of the posterior and upper walls is manifested by a symptom of their "overhang", which makes it difficult to view the eardrum. Traumatic effects on the lower jaw can lead to a fracture of the anterior bone wall of the ear canal.
Blood supply. The auricle is supplied by a.auricularis posterior and a.temporalis superficialis. Due to the fact that these arteries are not surrounded by subcutaneous fat, the auricle is especially prone to frostbite.
The blood vessels of the external auditory canal come from the branches of a.auricularis post., A.temporalis superficialis and a.auricularis profunda, forming a plexus around it. Cartilage does not contain its own vessels, its nutrition is diffuse from the vessels of the perichondrium, which also form the plexus. A.auricularis profunda is involved in the formation of the vascular plexus around the eardrum. All vascular plexuses are interconnected by longitudinal trunks running along the walls of the external auditory canal. Thanks to this combined vasculature in the external auditory canal, the most constant temperature in the human body is maintained at 37.00 C.
Venous outflow occurs according to v.auricularis ant. in v.temporalis superficialis and by v.auricularis post. in v.jugularis externa or v.retrormandibularis.
Lymph from the outer ear flows into nodi lymphatici mastoidei, nodi lymphatici parotidei and nodi lymphatici cervicales profundi.
Innervation. The auricle is innervated by n.auriculotemporalis, extending from n.maxillaris (III branch n.trigeminus) and n.auricularis magnus from plexus cervicalis.
On the front and upper walls of the external auditory canal, n.meatus acustici externi branches - the branch of n.auriculotemporalis. The posterior and lower walls of the external auditory canal are innervated by r.auricularis n.vagi (Arnold's nerve), so when an ear funnel is inserted into the ear canal and toilet some people have a reflex cough, and when washing the ear there may be a swoon. As part of this branch, sensitive, parasympathetic and sympathetic fibers pass to the ceruminous glands of the external auditory canal.
External auricular muscles are innervated by branches of the facial nerve.
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- EXTERIOR AND MIDDLE EAR
As you can see, there is nothing mysterious about converting sound waves into electrical impulses. According to one point of view, hearing is nothing more than a sense of pressure developed to perfection. Sound waves with a certain periodicity exert pressure on objects that they meet along the path of their propagation. This pressure is very low under normal conditions, and single
- MIDDLE EAR
The middle ear, auris media, includes the tympanic cavity with its contents, the airways of the mastoid process and the auditory tube. The tympanic cavity is separated from the external auditory meatus by the eardrum. There are auditory ossicles in it, transmitting sound vibrations to the ear labyrinth, and the muscles that regulate their position. Behind, the tympanic cavity opens into the antrum - a constant large
- INNER EAR
On the other side of the oval window, at the foot of the stepladder, there is a vestibule. The vestibule and the formations inside it are filled with a fluid that, in consistency, resembles a cerebrospinal fluid. Here, sound waves are finally transformed from air vibrations to fluid vibrations. The hearing organs of primitive vertebrates were adapted precisely to the liquid medium, and, in fact
- INNER EAR
The inner ear, auris interna, or labyrinth, labirinthus, is located in the depths of the pyramid of the temporal bone and consists of several intricately constructed cavities and channels that communicate with each other. A bone labyrinth or labyrinth capsule and the connective tissue or membranous labyrinth contained in it are isolated. The bony labyrinth, labyrinthus osseus, (Fig. 1.1.7) has walls consisting of
- AN EAR
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- Helps get foreign bodies into your ear, nose, eyes and respiratory tract
Foreign bodies of the external auditory meatus. There are two types of foreign bodies - living and nonliving. Living ones are insects (bugs, cockroaches, midges, flies, etc.), non-living ones are small objects (buttons, beads, peas, seeds from berries, seeds, pieces of cotton wool, etc.) that fall into the external auditory canal. Inanimate foreign bodies, as a rule, do not cause any pain and being in the ear
- Anatomy of the outer ear
The outer ear (Fig. 4.2) includes the auricle (auricula) and the external auditory meatus (meatus acusticus externus). At sh N and I r a k about in and n and it is located between a temporomandibular joint in front and a mastoid behind; it distinguishes between a concave outer surface and a convex inner, facing the mastoid process. The shell backbone is elastic cartilage
- EXTERNAL EAR INFLAMMATION
Inflammation of the outer ear affecting the skin of the auricle and the external auditory canal is a fairly common disease in cats, which most often develops due to tick-borne infestation. Therefore, in the absence of an opportunity to establish an accurate diagnosis, otitis media should be treated in combination with acaricidal (anti-mite) drugs such as the Bars drop, otovedin, or decor-2. It
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- Clinical anatomy of the external ear
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- Tumors of the outer ear
Benign tumors of the outer ear. Among the epithelial benign tumors, papilloma is often found on the skin of the external auditory canal and auricle. Treatment - excision, diathermocoagulation, cryodestruction and laser destruction. A rare tumor from the sulfur glands of ceruminoma grows slowly, with a pronounced tendency to malignancy. It is observed in people over 25 years old, similar to