Dorothy FarrarVestibulocochlear nerve
The vestibulocochlear nerve is the eighth of the twelve cranial nerves . It basically consists of two parts, namely the vestibular and the cochlear part.
Definition
The main tasks of the vestibulocochlear nerve are hearing and imparting the sense of balance. The nerve connects specific receptor areas in the inner ear to corresponding areas of the brain . However, it also includes some fibers that run from the brain to the inner ear and allow fine adjustment of the sense of hearing.
The vestibulocochlear nerve can be divided into the vestibular part, also known as the vestibular nerve, and the cochlear part or the N. cochlearis due to its different parts, which fulfill different functions.
Anatomy
The part of the vestibulocochlear nerve involved in mediating the sense of balance is the vestibular nerve. It was formerly also referred to as N. staticus. It consists of bipolar nerve cells whose cell bodies are located in the vestibular ganglion . The vestibular ganglion is located at the bottom of the internal auditory canal, the meatus acusticus internus, and can also be divided into two parts.
The processes originating from the vestibulocochlear nerve go to the inner ear receptor areas involved in the sense of balance. There are a total of eight main nerve cords: the utriculoampullary nerve, the utricular nerve, the anterior ampullary nerve, the lateral ampullary nerve, the posterior ampullary nerve and the saccular nerve.
Immediately after the vestibular ganglion, all the fibers are bundled together to form the vestibular nerve and pull together into the cranial cavity. During this process, the fibers belonging to the N. cochlearis accumulate, resulting in the formation of the N. vestibulocochlearis. The cochlear nerve is the portion of the eighth cranial nerve that is responsible for hearing. In the past it was also called N. acusticus. It also includes bipolar neurons. However, their cell bodies are located in the spiral ganglion, also known as the cochlear ganglion.
This nerve ganglion is located in a cavity that is centrally located within the cochlea coils. The associated nerve cell extensions pull to the hair cells of the organ of Corti. The individual nerve cells unite in their course to form the N. cochlearis. In the area of the inner auditory canal, they accumulate on the vestibular nerve, resulting in the vestibulocochlear nerve.
Function
The main functions of the vestibulocochlear nerve are, on the one hand, enabling hearing and, on the other hand, imparting the sense of balance. The nerve can be further divided into afferent and efferent parts. Afferent nerve fibers are defined as nerve fibers that transport information from the periphery to the brain. Efferent fibers, on the other hand, carry signals from the brain to the periphery.
Nerve impulses are generated in the vestibular organ and in the cochlea by so-called mechanoreceptors. The mechanoreceptors of the cochlea are used to perceive sound waves, those of the vestibular organ to perceive body position in order to obtain information for the coordination of balance. The afferent fibers now deliver the information from the sensory organs to the brain, more precisely to their specific nerve nuclei, in which further processing follows.
The efferent signals take the opposite route. They come from specific regions and nuclei of the brain and contain information about how specific organs should act. Both the afferent and efferent fibers are switched several times along the way. The purpose of this is that certain information should be made accessible to other bodies.
The sense of balance in particular is not only based on the vestibular organ, but also obtains a large part of the data necessary for its proper function from the sense of sight. Exact control of the body is only possible through the interconnections.
Diseases
- Acoustic neuron
- Positional Vertigo (BPLS)
In diseases of the vestibulocochlear nerve, at least in the early stages, the main symptoms are related to the affected part of the nerve. If the N. cochlearis is damaged, the main cause is hearing loss, while problems with the N. vestibularis result in a loss of balance .
The most common causes of damage to the vestibulocochlear nerve are craniocerebral trauma, neuritis and tumors . Damage to the vestibulocochlear nerve caused by craniocerebral trauma often manifests itself in balance disorders with dizziness and malaise.
Hearing impairments and even complete deafness can also occur. If the damage is unilateral, then nystagmus of the eyes is characteristic. Here, the eyes perform uninterrupted, rapid restoring movements, which otherwise only occur when rotating and stopping the same.
Nerve inflammation of the vestibulocochlear nerve usually manifests itself with similar symptoms. Reasons can be viral infections or circulatory disorders . Brain tumors also trigger similar symptoms. The most common tumor of the vestibulocochlear nerve is the acoustic neuroma, the treatment of which depends on the location in the brain and the condition of the patient.
Hello and welcome to my Health Guide & Encyclopedia! My name is Dorothy Farrar, and I'm the founder and main author of this platform.
My passion for health and wellness started at a young age when I became interested in the connection between the food we eat and the way we feel. This fascination led me to study nutrition and dietetics in college, where I learned about the importance of a balanced diet and the impact of various nutrients on the body.