yläcolliculus

The yläcolliculus, known in English as the superior colliculus, is a paired structure in the dorsal midbrain that forms part of the tectum. It sits above the cerebral aqueduct and works in concert with the inferior colliculus to integrate sensory information and guide orienting responses.

Anatomically, the superior colliculus is layered. The superficial layers primarily receive direct visual input from retinal ganglion cells, while deeper layers integrate multisensory information and generate motor commands. This organization supports the translation of sensory stimuli into rapid, coordinated movements of the eyes and head.

Functionally, the superior colliculus plays a key role in visually guided behavior. It mediates reflexive orientation to salient stimuli, contributes to the initiation and control of rapid eye movements (saccades), and participates in head and neck movements necessary to shift gaze. It also participates in attention and sensorimotor integration, helping to select targets for gaze based on multisensory cues.

Afferent connections include retinal inputs and various cortical and subcortical visual pathways, along with multisensory inputs from auditory and somatosensory systems. Efferent projections reach brainstem oculomotor nuclei to influence eye movements, as well as brainstem centers involved in head and neck control. The superior colliculus also projects to thalamic regions such as the pulvinar, linking it to higher-order processing and attentional networks.

Clinical relevance of the superior colliculus is typically seen in disorders of gaze control and visually guided behavior, where lesions can impair rapid orienting to stimuli while often sparing conscious visual perception.