The intraparietal sulcus (IPS) is the groove on the outer surface of each parietal lobe that separates the superior parietal lobule above from the inferior parietal lobule, the supramarginal and angular gyri, below. It has an oblique and a horizontal part, and areas in its walls guide eye movements, reaching and grasping, steer attention and handle numbers. [1][2][3]
The 3D brain needs JavaScript. The text below still says where the intraparietal sulcus is and what it does.
Seen from the left, above and behind: the superior parietal lobule is lit in blue, the supramarginal and angular gyri in orange, on both hemispheres. The groove runs where blue meets orange; the front (coronal) slice button cuts across it. Drag to turn, pinch or scroll to zoom, tap any part to name it; .
A groove has no shape of its own; lit: the parts on either side of it. Lit: above, the superior parietal lobule in blue; below, the supramarginal and angular gyri in orange. The horizontal part of the intraparietal sulcus separates the superior parietal lobule above from the inferior parietal lobule below, and the inferior parietal lobule is two gyri, the supramarginal in front and the angular behind. [2][3][1]
Where it is
It lies on the lateral (outer) surface of the parietal lobe and has two portions, an oblique one and a horizontal one. [1]
Its horizontal part is the lower border of the superior parietal lobule and the upper border of the inferior parietal lobule. [2][3]
Its walls hold a row of distinct areas named by position: the lateral and ventral intraparietal areas (LIP, VIP) for visual attention and quick eye movements (saccades); VIP and the medial area (MIP) for reaching and pointing; the anterior area (AIP) for grasping and handling objects; and the caudal area (CIP) for seeing depth with two eyes. All of them project to the frontal lobe. [1]
The dorsal attention network includes the intraparietal sulcus of each hemisphere, and it is activated when you turn your attention somewhere on purpose. [1]
It handles numbers: the right side is more involved in estimating quantities, the left in number symbols and operations. Nerve cells there fired while volunteers did calculations, and also when a patient merely said a quantity word such as “some more” or “bigger than the other one”. [1]
It links what is seen with what is felt to guide skilled hand actions such as using a tool, and its activity has been tied to learning sequences of finger movements. [1]
Inside it
Its subdivisions were worked out by recording single nerve cells in monkeys and by functional imaging in people, so the named areas are functional regions inside the groove, not separate folds. [1]
Other names
Often shortened to IPS; the prefix intra- (within) reflects that it runs within the parietal lobe rather than between lobes. [1][4]
Size
The model has no shape for the intraparietal sulcus, so the groove itself is not measured here. Measured from the model instead: on the left hemisphere, the stretch where the superior parietal lobule and the supramarginal and angular gyri come within 3 mm of each other fits in a box about 47 mm front to back, 49 mm top to bottom and 15 mm side to side (the box that stretch fits in, not the groove’s length along its bends or its depth). [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.