Vestibulocochlear nerve
The vestibulocochlear nerve (hearing balance nerve, from Latin vestibulum " atrium " and cochlea "snail" ) is the eighth cranial nerve. He was formerly known as nerve statoacusticus.
It is composed of two parts:
- The vestibular nerve ( staticus ) is the balance nerve,
- The cochlear nerve ( auditory ) of the auditory nerve.
The nerves transmit the afferent information from the respective receptor areas in the inner ear to the brain. In addition, there are also efferent pathways, which allow fine adjustment of the auditory nerve in the hearing sense.
Vestibular nerve
The vestibular nerve ( nerve outdated staticus ) is the balance nerve. The cell bodies of the bipolar neurons of the nerve are located in the vestibular ganglion ( Scarpa ganglion ). This ganglion consists of two definable subdivisions and is located at the bottom of the internal auditory canal ( internal auditory meatus ). The axons ( afferent and efferent ) to pull the receptor areas of the vestibular part of the inner ear. One distinguishes several nerve strands:
- Nerve utriculoampullaris: the macula of the utricle and ampulla of the membranous anterior and lateral
- Nerve utricularis: the macula of the utricle
- Ampullary nerve anterior: the ampulla of the membranous anterior
- Nervus ampullaris lateralis: the ampulla of the lateral membranous
- Posterior ampullary nerve: the ampulla of the posterior membranous
- Saccular nerve: the saccular
From the vestibular ganglion draw all men to the brain contracting fibers of these nerves as a single vestibular nerve into the cranial cavity. This leads to an accumulation of the fibers of the auditory nerve, causing the vestibulocochlear nerve arises.
The Vestibularanteile enter into the hindbrain to the trapezoidal body ( trapezoid body ). They end up mainly in the four vestibular nuclei ( vestibular or equilibrium cores):
- Medial vestibular nucleus,
- Lateral vestibular nucleus,
- Superior vestibular nucleus and
- Inferior vestibular nucleus
These nuclei are located in the hindbrain, in some mammals also in the hindbrain. Some fibers pass directly into the cerebellum and reticular formation in the. In the equilibrium cores, the first switchover to the secondary neurons that have links to almost all brain sections and to the spinal cord and provide a coupling of the equilibrium information with other body functions.
Cochlear nerve
The cochlear nerve ( auditory nerve ) is the auditory nerve. The nerve cell bodies of the bipolar neurons of the auditory nerve are located in the spiral ganglion ( ganglion cochlear ). This ganglion is in a cavity in the center of the spirals. The extensions of these nerve cells pull on the hair cells of the organ of Corti.
The axons of the nerve cells unite to form the cochlear nerve ( auditory ) and are deposited on the inner ear canal to the balance nerve to the vestibulocochlear nerve to. The Hörfasern end at the two Hörkernen - ventral cochlear nucleus and cochlear nucleus dorsalis - in Myelencephalon. Of these Hörkernen there are numerous connections to other brain areas, which travel along the auditory pathway to the auditory cortex ( Heschl Querwindung ) in the cerebrum.
Study possibilities for function of the auditory nerve are the promontory test and the ear canal electrostimulation.