A morphological evidence of direct connections from the cochlear nuclei to tensor tympani motoneurons in the cat: a possible afferent limb of the acoustic middle ear reflex pathways.

The central circuitry of the acoustic middle ear reflex activating the tensor tympani muscle was studied in the cat by tracer methods using horseradish peroxidase (HRP), wheat germ agglutinin (WGA) or HRP conjugated with WGA (WGA-HRP). The results indicate that the dorsal and ventral cochlear nuclei send fibers to motoneurons innervating the tensor tympani muscle, bilaterally with an ipsilateral dominance.