The precuneus is the part of the superior parietal lobule that lies on the inner (medial) face of each hemisphere, hidden between the two halves of the brain toward the back: in front of the cuneus of the occipital lobe, behind the somatosensory cortex and above the posterior cingulate. [1]
The 3D brain needs JavaScript. The text below still says where the precuneus is and what it does.
Opens cut down the midline and seen from the left, so you look at the inner face of the right hemisphere: the lit superior parietal lobule shows where it folds over onto that face, above the cingulate gyrus and in front of the occipital lobe; that inner stretch is the precuneus. Drag to turn, pinch or scroll to zoom, tap any part to name it; .
Lit: the whole superior parietal lobule, on both sides. The area is part of this lobule; its exact border is not drawn. It is the portion of the superior parietal lobule on the medial surface. The model’s superior parietal lobule shape runs over onto that inner face (it has hundreds of vertices within 5 mm of the midline) and has no precuneus of its own, so the whole lobule is lit. [1][2]
Because it lies deep between the hemispheres and is rarely injured on its own, it has been called “one of the less accurately mapped areas of the whole cortical surface”. [1]
What it does
Its front part is linked to mental imagery about the self and its back part to episodic memory, the recall of past events, including events about oneself, together with the left prefrontal cortex. [1]
It helps direct attention in space, both when making movements and when imagining or preparing them, and is active when a person takes a third-person rather than a first-person point of view. [1]
Imaging links it to reflective self-awareness, such as rating one’s own personality traits against other people’s, and with the posterior cingulate it has been called “pivotal for conscious information processing”. [1]
Connections
It has three subdivisions: a front, sensorimotor one wired to the paracentral lobule, the supplementary motor area, the premotor cortex and the insula; a central, cognitive one wired to the angular gyrus and prefrontal areas 10, 46 and 8; and a back, visual one along the parieto-occipital fissure wired to the cuneus and the primary visual cortex. [1]
It is one of the core regions of the default mode network, with the medial prefrontal cortex, the posterior cingulate cortex and the angular gyrus; networks are mapped differently from method to method, and even the precuneus’s place in that network has been questioned. [3][4]
Other names
Quadrate lobule of Foville, after Achille-Louis Foville. The Latin praecuneus was first used in 1868 and the English precuneus in 1879. [1]
Brodmann mapped it as the inner continuation of area 7 on the outer face of the parietal lobe. [1]
Size
The model has no shape for the precuneus itself, so it is not measured here. The whole left superior parietal lobule that holds it measures about 57 mm front to back, 67 mm top to bottom and 36 mm side to side on this model (the box it fits in, not its volume). [2]
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.