The inferior colliculi together with the superior colliculi, are collectively referred to as the corpora quadrigemina and form the roof of the midbrain.
The word colliculus actually means “lower hill” in Latin, describing the appearance of these structures.
The superior colliculi are part of the visual system, whereas the inferior colliculi are involved in the auditory system.
Auditory fibres project to the inferior colliculi, which then in turn project to the medial geniculate nucleus of the thalamus. From here, the fibres project to the auditory cortex within the temporal lobe.
Learn about the basic anatomy of the brain in this video.