All parts of the brain › Pathways › Superior longitudinal fasciculus

Where is the superior longitudinal fasciculus, and what does it join?

The superior longitudinal fasciculus (SLF) is the largest association bundle of the brain: nerve fibres running front to back high in the white matter of one hemisphere, joining the frontal lobe to the parietal lobe. It is described in three parts, SLF I, II and III, from top to bottom. [1][2]

A bundle has no shape of its own in this atlas; lit: the two parts it joins.

The 3D brain needs JavaScript. The legend below still names the two parts the superior longitudinal fasciculus joins.

Lit: its two ends, the frontal lobe in blue and the parietal lobe in orange.

Ends Slice

The brain starts seen from the left and a little from above, so the frontal lobe in front and the parietal lobe behind it both show along the top half of the side. One end is lit in blue (the frontal lobe), the other in orange (the parietal lobe); the bundle runs between them. Drag to turn, pinch or scroll to zoom; tap a lit part to name it.

The bundle itself is not drawn: BodyParts3D has no shape for any fasciculus, so each end lights its whole lobe, on both sides of the brain, not the strips of cortex its fibres reach. The fibres running between the two ends, deep under the cortex, are not lit. [3][1]

The two ends: which colour is which

Front end: the frontal lobe, lit in blue: the frontal lobe, on both sides of the brain.
In front, each part ends in a different strip of the frontal lobe: SLF I in its upper and inner cortex (Brodmann areas 6, 8 and 9) and the supplementary motor area, SLF II in the dorsolateral prefrontal cortex (areas 6, 8 and 46), SLF III in the ventral premotor cortex and the prefrontal cortex below it (areas 6, 44 and 46). [2][1]
Back end: the parietal lobe, lit in orange: the parietal lobe, on both sides of the brain.
Behind, they start in the parietal lobe: SLF I in the superior and inner parietal cortex, SLF II in the back of the inferior parietal lobule around the angular gyrus, SLF III in the supramarginal gyrus at its front. [2][1]

The bundle runs between the blue and the orange parts; its fibres are not drawn.

More about the superior longitudinal fasciculus

Other names: SLF [2][1]

Reil and Autenrieth found it by dissection at the beginning of the 19th century; Burdach refined the description, and the Dejerines followed in 1895. Its split into three parts comes from Petrides and Pandya, who traced it in the rhesus monkey about a century later. [1]
The arcuate fasciculus runs beside it, deeper down, and is sometimes counted as its fourth part (SLF IV). The review cited here argues against that: the SLF is in essence a fronto-parietal tract, while the arcuate is a fronto-temporal one passing through the parietal white matter beneath it. Only SLF III and the arcuate’s anterior segment seem to overlap. [1][4]
SLF I runs so close to the cingulum that some authors say the two cannot be told apart and SLF I should no longer be counted separately. [1]
SLF II, its major part, is thought to give the prefrontal cortex the parietal lobe’s information on visual space. The fibres carry signals both ways, so working memory in area 46 may in turn steer where spatial attention goes. [2]
SLF III is thought to carry body-sense information, such as for articulating speech, between the ventral premotor cortex, Brodmann area 44 (pars opercularis) and the supramarginal gyrus (area 40). [2]
Its two sides are not the same, but how they differ is not settled: one study tied a larger right SLF II to faster detection of things in the left half of the visual field, while other studies find SLF II larger on the left. [2][1]

The bundle tied to where attention goes: What part of the brain controls attention?

Sources

Facts describe anatomy and normal function only. The 3D model is the adult male BodyParts3D brain (credits and licence); it has no shape for any fibre bundle, so a bundle is shown by the two parts it joins.