<P> In some vertebrates, including fish and birds, the tectum is one of the largest components of the brain . In mammals, and especially primates, the massive expansion of the cerebral cortex reduces the tectum ("superior colliculus") to a much smaller fraction of the whole brain . It remains nonetheless important in terms of function as the primary integrating center for eye movements . </P> <P> Note on terminology: This article follows terminology established in the literature, using the term "superior colliculus" when discussing mammals and "optic tectum" when discussing either specific non-mammalian species or vertebrates in general . </P> <P> The two superior colliculi sit below the thalamus and surround the pineal gland in the vertebrate midbrain . It comprises the dorsal aspect of the midbrain, posterior to the periaqueductal gray and immediately superior to the inferior colliculus . The inferior and superior colliculi are known collectively as the corpora quadrigemina (Latin, quadruplet bodies). The brachium of superior colliculus (or superior brachium) extends laterally from the superior colliculus, and, passing between the pulvinar and medial geniculate body, is partly continued into an eminence called the lateral geniculate body, and partly into the optic tract . </P> <P> The microstructure of the optic tectum / superior colliculus varies across species . As a general rule, there is always a clear distinction between superficial layers, which receive input primarily from the visual system and show primarily visual responses, and deeper layers, which receive many types of input and project to numerous motor - related brain areas . The distinction between these two zones is so clear and consistent that some anatomists have suggested that they should be considered separate brain structures . </P>

Where is the superior colliculus located in the brain
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