Point 23
Intro
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Point 23. Superior Colliculus |
The superior colliculi form the rostral two bumps (one on each side) on the dorsal aspect of the midbrain. The caudal two bumps are the inferior colliculi and together they (inferior and superior colliculi) comprise the TECTUM or roof of the midbrain. In contrast to the inferior colliculus, which is an AUDITORY structure, the superior colliculus is usually described as a VISUAL reflex center. It is a highly laminated (layered). The top or dorsal-most three layers receive visual information primarily from two sources, i.e., the retina (retinocollicular) and the visual cortex (area 17; corticotectal). In contrast to the exclusively visual nature of the superficial layers, the intermediate and deep layers receive projections from many functionally different areas of the brain. These inputs are both "motor" and "sensory". Since the latter category includes visual, auditory and somatosensory inputs, you can see that the superior colliculus is not exclusively related to visual function. Instead, it plays a role in helping orient the head and eyes to all types of sensory stimuli.
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