Definition of tectum in English:



  • 1The uppermost part of the midbrain, lying to the rear of the cerebral aqueduct.

    • ‘Each trochlear nerve makes its exit through the caudal tectum (the dorsal portion of the midbrain), immediately lateral to the frenulum of the superior medullary velum.’
    • ‘Although medial and lateral gaze palsies are typical, patients usually retain upper eyelid control and vertical eye movement because of sparing of the mid-brain tectum, which allows communication.’
    • ‘Recently, we presented evidence for an involvement of histamine in the generation and organization of such defensive reactions in the midbrain tectum.’
    1. 1.1 A rounded swelling (colliculus) forming part of the tectum and containing cells involved in the visual system.
      • ‘In fish, the optic tecta and cerebellum, which can be thought of as the functional equivalent of the optic lobes, occupy approximately one-half of total brain volume.’
      • ‘Cavefish have reduced the size of their optic tecta, the region of the brain responsible for interpreting visual information.’
      • ‘Brains were removed and dissected into telencephalon (excluding the olfactory bulbs), hypothalamus (excluding the pituitary), optic tectum, and brain stem (excluding the cerebellum).’
      • ‘Electrophysiological recordings from the optic tectum of the pigeon and the Bobolink revealed the presence of neurons that respond to changes in the direction of the ambient magnetic field, but only in the presence of light.’
      • ‘However, expression appeared to be greater in the cerebellum, ectostriatum, paleostriatum, and layers of the optic tectum, suggesting regional differences in regulation.’


Early 20th century: from Latin, literally ‘roof’.