The midbrain contains the superior and inferior colliculi.
Together these paired bumps form the tectum, a dorsal part of the midbrain. The superior colliculi help coordinate visual orienting responses, such as turning the eyes or head toward a stimulus. The inferior colliculi are important relay and processing centers in the auditory pathway before signals reach the medial geniculate body and auditory cortex.
The midbrain is the uppermost division of the brainstem, positioned between the pons and the diencephalon. Besides the colliculi, it contains the cerebral peduncles, periaqueductal gray matter, substantia nigra, and red nucleus. These structures contribute to movement, pain modulation, eye control, and arousal.
The colliculi are sometimes called the “corpora quadrigemina,” meaning fourfold body, because there are two superior and two inferior colliculi. They are not part of the cerebral cortex and should not be confused with the visual and auditory cortices that receive later-stage sensory information.