lateral lemniscus(redirected from lateral fillet)
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a bundle of ascending fibers that originate from the cochlear and auditory relay nuclei of the rhombencephalon, enter the trapezoid body, a transverse fiber stratum in which about half their number decussate, and from here turn rostrally along the lateral side of the spinothalamic tract; in the midbrain, it arches superiorly and enters the inferior colliculus in which all of its fibers terminate; the auditory pathway is transsynaptically extended from here by the brachium of the inferior colliculus to the medial geniculate body of the thalamus, from which in turn the auditory radiation leads to the auditory cortex; intercalated in the trapezoid body and along the ascending trajectory of the lemniscus are several cell groups in which part of the fibers synapse.
An axon tract originating in the cochlear nuclei and ascending to synapse in the inferior colliculi; axons from the inferior colliculi ascend to synapse in the medial geniculate nucleus of the thalamus. This lemniscus is a middle link in the circuit carrying auditory information to the auditory cortex (Heschl's gyrus).
See also: lemniscus