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D. Cochlear nuclei
—are the only auditory nuclei that do not receive binaural input, -
damage results in unilateral deafness.
1. Dorsal cochlear nucleus
-underlies the acoustic tubercle of the floor of the fourth ventricle,
—receives input from the cochlear nerve (CN VIII). -projects
contralaterally to the lateral lemniscus.
2. Ventral cochlear nucleus
-receives input from the cochlear nerve (CN VIII). -
projects bilaterally to the superior olivary nuclei, -
projects contralaterally to the lateral lemniscus. -gives
rise to the trapezoid body (ventral acoustic striae).
E. Superior olivary nucleus
-is located in the pons at the level of the facial nucleus.
-receives input from ventral cochlear nuclei.
-projects bilaterally to the lateral lemniscus.
-plays a role in sound localization and binaural processing.
-gives rise to the efferent olivocochlear bundle, a cochlear feedback pat hway.
F. Trapezoid body
-is located in the caudal pontine tegmentum at the level of the abducent
-is transversed by intra-axial abducent fibers of CN VI. -contains
decussating fibers from the ventral cochlear nucleus.
G. Lateral lemniscus
-receives input from the contralateral cochlear nuclei.
-receives input from the superior olivary nuclei.
-is connected to the contralateral lateral lemniscus via commissural fibe rs.
—projects to the nucleus of the inferior colliculu s.
Chapter 11 Auditory System I 181
H. Nucleus of the inferior colliculus
-receives input from the lateral lemniscus.
-projects via the brachium of the inferior colliculus to the medial
geniculate body, —projects to the superior colliculus to mediate audiovisual
I. Medial geniculate body (see Figures 1-6 and 11-1) —receives input from
the nucleus of the inferior colliculus. -projects via the auditory radiation
to the primary auditory cortex, the transverse gyri of Heschl (areas 41
J. Auditory radiation (see Figures 11-1 and 16-3)
-extends from the medial geniculate body via the posterior limb of the
internal capsule to the transverse gyri of Heschl.
K. Transverse temporal gyri of Heschl (see Figure 11-1)
-contain the primary auditory cortex (areas 41 and 42). -
are located in the depths of the lateral sulcus. -receive
auditory input via the auditory radiation, -project to the
auditory association cortex (area 22).
IV. Efferent Cochlear (Olivocochlear) Bundle
-is a crossed and uncrossed tract that arises from the superior olivary
nucleus and projects to the hair cells of the organ of Corti. -