The precentral sulcus is the groove that runs parallel to and in front of the central sulcus on the outer side of each frontal lobe. It divides the precentral gyrus behind it from the superior, middle and inferior frontal gyri in front. In most brains it is in two parts, the superior and inferior precentral sulci. [1]
The 3D brain needs JavaScript. The text below still says where the precentral sulcus is and what it does.
Seen from the left and above: the precentral gyrus is lit in blue, the superior, middle and inferior frontal gyri in orange, on both hemispheres. The groove runs where blue meets orange; the top (axial) 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: behind, the precentral gyrus in blue; in front, the superior, middle and inferior frontal gyri in orange. The precentral sulcus lies parallel to and in front of the central sulcus and divides the superior, middle and inferior frontal gyri in front from the precentral gyrus behind. [1][2]
The outer surface of the frontal lobe has three horizontal gyri ahead of the precentral gyrus, the superior, middle and inferior frontal gyri, and the precentral sulcus divides all three from it. [3][1]
The middle frontal gyrus is bounded behind by it; behind the inferior frontal gyrus, past the inferior precentral sulcus, lies the precentral gyrus. [4][5]
In most brains it is split into two parts, the superior and inferior precentral sulci; sometimes it is in three parts, and sometimes it forms one continuous groove. [1]
What it does
It is a landmark for the motor strip behind it: the primary motor cortex lies on the front wall of the central sulcus and extends onto the precentral gyrus, and the front of the gyrus, next to this groove, holds premotor areas. [6]
The frontal eye field lies around where the back of the middle frontal gyrus meets the precentral gyrus, so near this groove. [7]
In front of its lower part lies the back of the inferior frontal gyrus, the pars opercularis, which with the pars triangularis makes up Broca’s area. [5]
Other names
Its two usual parts are named the superior precentral sulcus and the inferior precentral sulcus. [1]
Size
The model has no shape for the precentral sulcus, so the groove itself is not measured here. Measured from the model instead: on the left hemisphere, the stretch where the precentral gyrus and the superior, middle and inferior frontal gyri come within 3 mm of each other fits in a box about 54 mm front to back, 67 mm top to bottom and 60 mm side to side (the box that stretch fits in, not the groove’s length along its bends or its depth). [8]
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.