The parieto-occipital sulcus is a deep groove near the back of the brain that marks the border between the parietal lobe in front and the occipital lobe behind. Most of it lies on the inner (medial) face of each hemisphere; only a short part reaches the outer surface. [1][2]
The 3D brain needs JavaScript. The text below still says where the parieto-occipital sulcus 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 parietal lobe is lit in blue, the occipital lobe in orange. The groove runs where blue meets orange; the side (sagittal) 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: in front, the parietal lobe in blue; behind, the occipital lobe in orange. The parieto-occipital sulcus marks the boundary between the parietal and occipital lobes; its chief part is on the inner (medial) surface of the hemisphere, so this page opens cut down the midline. [1][2]
Where it is
Its medial part runs downward and forward as a deep cleft on the inner face of the hemisphere and joins the calcarine sulcus a little below and behind the back end of the corpus callosum. [1][3]
Its lateral part, the short notch seen on the outer surface, lies about 5 cm in front of the back tip of the hemisphere (the occipital pole) and is about 1.25 cm long. [1]
On the inner face it separates the precuneus in front, the inner part of the superior parietal lobule, from the cuneus behind, the wedge of occipital lobe above the calcarine sulcus. [1][4][5]
On the outer surface there is no obvious border between the parietal and occipital lobes; the clear landmark between them is this groove on the inner surface. [2][1]
What it does
It is a landmark rather than a working part: in front of it the precuneus works on episodic memory, visuospatial processing and reflections upon self; behind it the cuneus handles basic visual processing. [4][5]
The back part of the precuneus, along the parieto-occipital fissure, connects with visual areas in the cuneus and the primary visual cortex. [4]
The visual area V6 lies near the deep midline groove and typically includes part of the cortex of the parieto-occipital sulcus. [6]
Inside it
In most brains the groove holds a gyrus buried in its depth. [1]
The model has no shape for the parieto-occipital sulcus, so the groove itself is not measured here. On the left hemisphere, the stretch where the parietal lobe and the occipital lobe come within 3 mm of each other fits in a box about 40 mm front to back, 37 mm top to bottom and 46 mm side to side (the box that stretch fits in, not the groove’s length along its bends or its depth). [7]
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.