Corpora Quadrigemina

Two pairs of rounded knobs on the upper surface of the midbrain mark the location of four nuclei, which are called collectively the "corpora quadrigemina." These masses contain the centers for certain visual reflexes, such as those responsible for moving the eyes to view something as the head is turned. They also contain the hearing reflex centers that operate when it is necessary to move the head so that sounds can be heard better.