The tectum (Latin: roof) is the dorsal part of the midbrain, derived in embryonic development from the alar plate of the neural tube. In adult humans it is present only in the mesencephalon (midbrain), as the inferior and the superior colliculi.
The superior colliculus is involved in preliminary visual processing, and control of eye movements. In non-mammalian vertebrates, it serves as the main visual area, functionally analogous to the visual areas of the cerebral cortex in mammals.
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.
