Preddverno cochlear nerve: description, structure, and anatomy

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2018-03-19 00:05:57

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Anatomists distinguish twelve pairs of nerves, which have specific functions and are located within the area of the head and neck. One of them is the vestibulocochlear nerve. He is responsible for the special sensitivity: hearing and sense of balance. Disturbance of its functions or of anatomy can lead to profound disability.

Structure

preddverno cochlear nerve

What is the vestibulocochlear nerve? Its anatomy is quite complex, because, as the name suggests, includes two separate roots having different functions. First – vestibular, responsible for balance and innervates semicircular canals of the inner ear. Second – auditory, conducts impulses from the labyrinth of the cochlea to its back.

The origins of the nerve takes on the lower surface of the hemispheres, leaving the gray matter nuclei of the olive in the medulla oblongata which is situated below the facial nerve. Auditory branch starts from the burl of a snail and its peripheral processes end in the spiral organ, and Central exits through the top of the pyramid of the auditory bones in the brain and reaches the cochlear nuclei.

Second, the vestibular branch also starts with the knot located in the inner ear. The dendrites of these neurons go to the semicircular canals, spherical and elliptical sacs. And axon as part of the vestibular spine is sent in a diamond-shaped fossa and terminates in the vestibular nuclei.

Providing hearing

preddverno cochlear nerve anatomy

Perception of sound in humans is quite difficult. There are outer, middle and inner ear, but vestibulocochlear nerve innervates exclusively the inner part. First, a sound wave is perceived by the eardrum. Its vibrations are transferred to the hammer, anvil, and stirrup, connected together. With a wave of the stapes touches the oval window located ahead of the maze. Vibrations cause displacement of perilymph and the endolymph within the labyrinth. Together with the liquid range and plots the secondary tympanic membrane, or basilar records. It is located on sound the hairs, generating the nerve impulse. It is a spiral node, located in the inner ear. Outgrowths from nerve cells that make up the site, go through the hole in the ear canal and coupling with Predgorny nerve, go to the bridge where and ends in the substance of the cochlear nuclei in rhomboid fossa.

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Cochlear Axons of the neurons crisscross and form a lateral loop. Then the fibers are separated. A small part of them ends up on the lower hills of lamina quadrigemina (middle brain). The rest go to the medial geniculate bodies in the intermediate brain or in the median thalamus.

Balance

lose preddverno cochlear nerve

For the balance of the body in space during movement and at rest also meets the vestibulocochlear nerve. Scheme of innervation of the uninitiated could cause confusion, so as to ensure that this function required the simultaneous operation of many parts of the nervous system.

The Main function of the vestibular apparatus lies in the fact that in each moment of time to analyze the position of the head in space and to adjust the position of the body and muscle tone. The body responsible for balance near the labyrinth in the middle ear and consists of three intersecting canal oval shape that end with elliptic and spherical saccules. Within these structures are hairs that are sensitive to changes in head position, angular and linear acceleration, and change gravity.

From the sensitive hairs of the peripheral processes of neurons are sent to predgornomu node, located at the bottom of the temporal bone. Entering into the substance of the brain, the nerve is directed to a diamond-shaped hole to the vestibular nuclei. From the bridge the processes of the neurons differ in the spinal cord (anterior horn nuclei), the cerebellum (bark worm), the thalamus (vestibular nuclei) and the reticular formation (nuclei of cranial nerves). All these structures provide friendly the body's reaction to irritation of the vestibular receptors. All information from subcortical structures is supplied in the region of the middle and inferior temporal gyrus, where the center of motor functions, center of General sensitivity and the center of the body scheme.

Hearing Research

preddverno cochlear nerve diagram

What you need to do to check how well it performs its functions vestibulocochlear nerve? Its two branches are examined separately. Hearing evaluation performed by ENT doctors, neurologists and even psychiatrists, therefore, was designed the same for all specialties the tests.

It All starts with a simple hearing test. Normal people needs from a distance of five meters to hear addressed to him whispered speech. Hearing loss or the lack of it can cause not only lesions of the outer or middle ear, but also internal. Therefore, it is important to understand the causes of the disease.

  1. Schwabach Test is based on measuring the length of bone conduction. Include tuning fork and place on mastoid process behind the ear. If the patient does not hear sound, then the problem is in the inner ear, if the sound is heard longer than necessary, the pathology is located in the middle section of the analyzer.
  2. Rinne Test determines the difference between the air and bone conductivity. Included a tuning fork set on the mastoid process and the patient is asked to say when he ceases to hear the sound. After that, the tool is transferred to the ear. In the case when the patient is healthy, the sound will still be heard.
  3. Test Weber. Re-enabled the tuning fork is placed on the parietal region of the person, and the doctor asks which side the sound is heard better. If the patient indicates the patient's side, this speaks in favor of the damage of the middle ear, and if healthy, the problems in the inner ear.

Assessment of the balance

preddverno cochlear nerve innervates

The vestibulocochlear nerve is also responsible for balance, so neurologists in the comprehensive examination often resort to different tests to check the patient's stability:

  1. Posture Romberga is one of the most popular options. The patient is asked to stand up straight so that the feet were on one line and the heel of one foot rested on the second sock. Hands must be extended or straightened in front of him. Then the doctor asks to take a few steps forward, first with eyes open and then closed. Unsteadiness of gait in the second case indicates a lesion of the internal ear.
  2. Test Mittelmeer. The patient walks in place with eyes closed. If there is a lesion of the vestibular apparatus, then it will gradually turn in the direction of the hearth.

Lose the cochlear branch

neurinoma preddverno cochlear nerve

The defeat of the vestibulocochlear nerve to the area responsible for processing auditory impulses, has specific clinical manifestations. There are two variant of reduce:

- violation of zvukoprovodnost, or conductive hearing loss (middle ear lesions);
- sensorineural hearing loss in lesions of the inner ear.

In the first case, the reasons for the condition may be inflammation, sclerosis of the tissues or neoplastic disease. The second variant of the disease also can be caused by inflammatory phenomena, neurinoma, as well as damage to the substance of the brain in the areas of location of the nuclei of the eighth cranial nerves.

Clinically it is manifested by complaints of noise in the ear, headache, General hearing loss. If the pathological process is located deep in the brain, it may be a loss of function of neighboring nerves such as the vestibular, trigeminal and facial. This community of symptoms is called "alternating syndrome".

Defeat of the vestibular part

preddverno innervation of the cochlear nerve

The pathology of the vestibulocochlear nerve at the site of the vestibular branch will primarily manifest itself with dizziness, nausea (sometimes with vomiting) and nystagmus. This nerve is partly responsible for the position of the eyeball when changing head position, therefore, its defeat may be a change in eye movement. Namely, small horizontal or vertical twitches.

In addition, the patient has unsteady gait, and he must stretch down (like on a ship during pitching) to keep the balance, as well as to constantly monitor their feet. Therefore, such people have a doctor can suggest the diagnosis at that moment, when they enter his office.

Neuroma vestibulocochlear nerve

Innervation of vestibulocochlear nerve suggests that its fibers are covered by the sheath of Schwann cells. It is a kind of insulation to the nerve impulse is not passed to other fibers. But from the cells of the sheath in rare cases (one hundred thousand) can grow benign tumor.

It is slow and, as a rule, when the tumor has reached considerable size. Patients complain of decreased hearing on one side, dizziness, pain in the side of the face, and the presence of concomitant pathology of the l...


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AR: https://tostpost.com/ar/health/13681-preddverno.html

BE: https://tostpost.com/be/zdaro-e/24462-preddverno-ulitkovyy-nerv-ap-sanne-budova-anatom-ya.html

DE: https://tostpost.com/de/gesundheit/24475-preddverno-das-cochlear-nerv-beschreibung-aufbau-und-anatomie.html

ES: https://tostpost.com/es/la-salud/24501-preddverno-ulitkovyy-nervio-ptico-descripci-n-estructura-y-anatom-a.html

HI: https://tostpost.com/hi/health/13701-preddverno.html

JA: https://tostpost.com/ja/health/13704-preddverno.html

KK: https://tostpost.com/kk/densauly/24443-preddverno-ulitkovyy-nerv-sipattamasy-rylysy-zh-ne-anatomiyasy.html

PL: https://tostpost.com/pl/zdrowie/24376-preddverno-ulitkovyy-nerw-opis-budowa-i-anatomia.html

PT: https://tostpost.com/pt/sa-de/24384-preddverno-coclear-do-nervo-a-descri-o-a-estrutura-e-anatomia.html

TR: https://tostpost.com/tr/sa-l-k/24451-vestibulokoklear-ulitkovyy-sinir-tan-m-yap-s-ve-anatomisi.html

UK: https://tostpost.com/uk/zdorov-ya/24422-pereddverno-ul-tkoviy-nerv-opis-budova-anatom-ya.html

ZH: https://tostpost.com/zh/health/14426-preddverno.html






Alin Trodden - author of the article, editor
"Hi, I'm Alin Trodden. I write texts, read books, and look for impressions. And I'm not bad at telling you about it. I am always happy to participate in interesting projects."

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