The superior colliculus is a pair of small rounded bumps on the back (roof) of the midbrain, just below the pineal gland and the back end of the corpus callosum, with the inferior colliculi directly beneath them. It turns the eyes, and the head, toward things you see, hear or feel. [1]
The 3D brain needs JavaScript. The text below still says where the superior colliculus is and what it does.
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Opens cut by a side (sagittal) slice through the superior colliculus. Drag to turn, pinch or scroll to zoom, tap any part to name it; .
Takes part in: vision — see every part of each lit together.
Where it is
A paired structure on the back (dorsal) side of the midbrain, part of the midbrain tectum, the roof that lies behind the cerebral aqueduct. [1][2]
The two superior colliculi sit below and behind the pineal gland and the splenium (back end) of the corpus callosum; the pulvinar of the thalamus overhangs them, and a medial geniculate body lies to the side of each. [1][3]
The two inferior colliculi lie directly below them; the four together are the corpora quadrigemina (Latin for “quadruplet bodies”). The superior pair is the larger, though the inferior pair stands out more. [1]
What it does
Its superficial layers take input straight from the retina and respond almost only to what is seen; many neurons in its deeper layers also respond to sound or touch, and some to several senses at once. [1]
Each layer holds a map of the space around you, and activity at one point of the map drives a response toward that point; in primates this is best known as the saccade, the quick jump of both eyes from one fixed point to the next. [1][4]
In primates it also helps make head turns, arm reaches and shifts of attention with no visible movement, and it remains the main integrating centre for eye movements. [1]
In species with a fovea, its front part holds many “fixation” neurons that fire steadily while the eyes stay still on one point. [1]
Connections
In, to the top layers: the retina of both eyes (more from the opposite eye), the primary and secondary visual cortex (areas 17, 18 and 19) and the frontal eye fields. [1]
In, to the deeper layers: most areas of the cerebral cortex, and an inhibitory (GABA) input from the substantia nigra pars reticulata of the basal ganglia that is thought to gate it. [1]
Out: to the pulvinar and nearby parts of the thalamus, which pass the signal on to cortex that controls eye movements; to the lateral geniculate nucleus; and down two large pathways to the brainstem and spinal cord. [1]
The brachium of the superior colliculus runs out from its side, between the pulvinar and the medial geniculate body, into the lateral geniculate body and the optic tract. [1]
Inside it
Seven layers in mammals: three superficial (stratum zonale, superficial grey layer, optic layer), two intermediate (intermediate grey and white layers) and two deep (deep grey and white layers); the deepest lies directly on the periaqueductal grey. [1]
The layers are not smooth sheets but a honeycomb of separate columns, estimated at around 100 in all. [1]
Other names
Superior colliculi (the pair); the name is Latin for “upper hill”. With the inferior colliculi it forms the tectum (“roof”) of the midbrain, also called the corpora quadrigemina; the matching structure in fish, frogs and birds is the optic tectum. [1]
Size
On this model the left superior colliculus measures about 6 mm front to back, 6 mm top to bottom and 8 mm side to side (the box it fits in, not its volume); the right one is its mirror image. [5]
Centre of the left superior colliculus compared with the centre of the pineal gland: 7 mm further forward, 4 mm lower, 4 mm further from the midline; 9 mm apart in a straight line. [5]
Centre of the left superior colliculus compared with the centre of the left inferior colliculus: 8 mm higher; 8 mm apart in a straight line. [5]
Facts describe anatomy and normal function only. The 3D model is the adult male BodyParts3D brain (credits and licence); real brains vary in size and shape, so its measurements describe one model, not anyone’s brain.