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The cochlear nucleus is
the first nucleus in the auditory nervous system, but it is a good
illustration of the complexity of the pathways from the very beginning. The
structures labeled MSO, LSO and MNTB are actually parts of the superior
olive, the medial superior olive, the lateral superior olive and the medial
nucleus of the trapezoid body. The structure through which the nerve fibers
pass between the side of the brain in this vicinity is called the trapezoid
body. Notice that the anterior part of the ventral cochlear nucleus (AVCN)
projects to the ipsilateral LSO and the contralateral MNTB. But the AVCN also
sends a second projection to the MSO. So this one part of the cochlear
nucleus has already set up two different pathways. The posterior part of the
ventral cochlear nucleus (PVCN) and the dorsal cochlear nucleus (DCN) bypass
the LSO, MSO and MNTB and head straight up the lateral lemniscus. But notice
that they branch off around the superior olive (these are called periolicvary
areas).
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