Midbrain tectum

The tectum (Latin: roof) is a region of the brain, specifically the dorsal part of the mesencephalon (midbrain). This is contrasted with the tegmentum, which refers to the region ventral to the ventricular system. The tectum is responsible for auditory and visual reflexes.

It is derived in embryonic development from the alar plate of the neural tube.

Colliculi

In adult humans, it only consists of the inferior and the superior colliculi.

Both colliculi also have descending projections to the paramedian pontine reticular formation and spinal cord, and thus can be involved in responses to stimuli faster than cortical processing would allow. Collectively the colliculi are referred to as the corpora quadrigemina.