Cochlear nucleus

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Position of the two cochlear nuclei within the auditory pathway .

The nuclei cochleares ("snail cores") are two core areas ( nuclei ) in the brain stem that are used to switch the auditory pathway for the first time . The afferents run in the cochlear nerve (part of the 8th cranial nerve ), which transmits hearing information from the organ of Corti from the inner ear to the brain. A distinction is made between two snail cores, which extend at the bottom of the diamond pit from the medulla oblongata to the pons :

  • Nucleus cochlearis anterior (anterior cochlear core )
  • Nucleus cochlearis posterior (posterior snail core)
Schematically a cross section through the hindbrain with 4th ventricle (13) at the level of VIII Nn vestibular (1) and cochlear (2) and the front (3) and rear (4) screw cores - are colored blue fiber trains of auditory pathway to olivary nucleus superior (upper olive, 7), mostly crossing in the corpus trapezoideum (trapezoidal body, 8) and ascending further as Lemniscus lateralis (10). The nuclei corporis trapezoidei (9) are embedded in the trapezoidal body.
Only half of the fibers crossing the midline ( raphe , 11) are shown; The tracts of the descending pyramidal tract (12) are shown in red .

Nucleus cochlearis anterior

Most of the efferents of the anterior snail nucleus cross to the other side of the brain (contralateral) and form a transverse structure on the underside of the brain that is visible from the outside, the corpus trapezoideum . Most of the axons in the lateral lemniscus then run to the respective lower hill ( colliculus inferior ) of the four- hill plate ( lamina quadrigemina ). Some of the efferents move to the corpus geniculatum mediale and from there via the auditory radiation to the auditory cortex .

Some of the fibers run from the corpus trapezoideum to the ocular muscle nuclei ( Nucleus nervi abducentis , Nucleus nervi oculomotorii and Nucleus nervi trochlearis ). Reflective eye movements to a sound source are conveyed via these nerve tracts .

If the nucleus is damaged on one side, directional hearing is impaired and hearing on the same side is impaired ( hypacusis ).

Posterior cochlear nucleus

The efferents of the posterior cochlear nucleus also cross to the opposite side in the medullary striae and run in the lateral lemniscus to the contralateral lower mound.

literature

  • Karl-Josef Moll, Michaela Moll: Anatomy: Short textbook for the subject catalog 1 . Elsevier, Urban & FischerVerlag, 18th edition 2005, ISBN 9783437417436 , p. 639.