page_title: Superior colliculus
section_title: Structure
hierarchical_section_title: Superior colliculus / Structure
caption_attribution_description: Hind- and mid-brains; postero-lateral view.
context_page_description: The superior colliculus is a structure lying on the roof of the mammalian midbrain. In non-mammalian vertebrates, the homologous structure is known as the optic tectum, or optic lobe. The adjective form tectal is commonly used for both structures.
  In mammals, the superior colliculus forms a major component of the midbrain. It is a paired structure and together with the paired inferior colliculi forms the corpora quadrigemina. The superior colliculus is a layered structure, with a number of layers that varies by species. The layers can be grouped into the superficial layers and the deeper remaining layers. Neurons in the superficial layers receive direct input from the retina and respond almost exclusively to visual stimuli. Many neurons in the deeper layers also respond to other modalities, and some respond to stimuli in multiple modalities. The deeper layers also contain a population of motor-related neurons, capable of activating eye movements as well as other responses.
  The general function of the tectal system is to direct behavioral responses toward specific points in egocentric space.
context_section_description: The superior colliculus is a synaptic layered structure. The two superior colliculi sit below the thalamus and surround the pineal gland in the mammalian midbrain. It comprises the dorsal aspect of the midbrain, posterior to the periaqueductal gray and immediately superior to the inferior colliculus. The inferior and superior colliculi are known collectively as the corpora quadrigemina (Latin, quadruplet bodies). The superior colliculi are larger than the inferior colliculi, though the inferior colliculi are more prominent. The brachium of superior colliculus (or superior brachium) is a branch that extends laterally from the superior colliculus, and, passing between the pulvinar and medial geniculate body, is partly continued into an eminence called the lateral geniculate body, and partly into the optic tract.
  The superior colliculus is associated with a nearby structure called the parabigeminal nucleus, often referred to as its satellite. In the optic tectum this nearby structure is known as the nucleus isthmi.
caption: Hind- and mid-brains; postero-lateral view. Superior colliculus labeled in blue.
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