tectal

Tectal is an anatomical term referring to the tectum, the dorsal part of the midbrain (the mesencephalon). The word tectum comes from Latin tectum, meaning “ceiling.” In mammals, the tectum comprises two paired structures, the superior colliculus (often called the optic tectum) and the inferior colliculus (the auditory tectum), which together form the core of the dorsal midbrain.

The superior colliculus and the inferior colliculus have distinct roles. The superior colliculus receives direct input from the retina and from higher visual areas, with its superficial layers processing visual information and deeper layers integrating multisensory and motor signals. It acts as a center for orienting movements, guiding rapid eye and head movements toward salient stimuli, and giving rise to the tectospinal tract that influences neck and trunk reflexes. The inferior colliculus is a major relay in the central auditory pathway, receiving ascending auditory input from the cochlear nuclei via the brainstem's auditory pathways and projecting to the medial geniculate body of the thalamus, which in turn relays to the auditory cortex.

Developmentally, the tectum forms from the dorsal region of the mesencephalon, with the tectal plate giving rise to its layered structure. Comparative anatomy shows the optic tectum is prominent in non-mammalian vertebrates, while in mammals the superior colliculus retains many of its ancestral visual functions alongside multisensory processing.

Clinically, lesions affecting tectal regions can impair reflexive gaze, orienting responses, and auditory localization, and may contribute to broader midbrain syndromes.