Where is the inferior fronto-occipital fasciculus, and what does it join?
The inferior fronto-occipital fasciculus (IFOF) is one of the longest association bundles in the human brain, joining the frontal lobe to the occipital lobe within one hemisphere. From the front it runs back low, through the temporal stem, and fans out into the occipital lobe and nearby parietal and temporal cortex. [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 inferior fronto-occipital fasciculus joins.
The brain starts seen from the left, so the frontal lobe at the front and the occipital lobe at the back, the bundle’s two far ends, both show. One end is lit in blue (the frontal lobe), the other in orange (the occipital 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. Its fibres fanning into the parietal and back temporal cortex are not lit, nor is its narrow middle stretch through the temporal stem and the extreme and external capsules. [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.
Back end: the occipital lobe, lit in orange: the occipital lobe, on both sides of the brain.
Behind, its core ends in the occipital lobe (areas 18 and 19). Its upper layer also reaches the upper occipital lobe, the precuneus and the angular gyrus; its lower layer the lower occipital lobe and the basal and back temporal cortex. [1]
The bundle runs between the blue and the orange parts; its fibres are not drawn.
More about the inferior fronto-occipital fasciculus
Herbert Mayo engraved fibres passing above the temporal horn of the lateral ventricle, through the temporal stem and the limen insulae to the frontal lobe, in 1823; Theodor Meynert described them by blunt dissection, and in 1909 Curran called it a large bundle uniting the occipital with the frontal lobe. [1]
Gray’s Anatomy (1918) traces it backward from the frontal lobe along the outer border of the caudate nucleus, its fibres then spreading like a fan into the occipital and temporal lobes beside the back and lower horns of the lateral ventricle. [2]
In the temporal stem it lies just above the uncinate fasciculus. Before birth the two can be separated by dissection only behind the limen insulae, and the pair seems to mature before the other cortical bundles, which can be told apart from about the 30th week of gestation; the arcuate–superior longitudinal complex only from the 32nd to the 35th week. [1]
Some sources also name a superior fronto-occipital fasciculus, but it is no longer believed to exist in the human brain. [2]
Whether monkeys have one is disputed: tract-tracing in macaques found a temporal-to-frontal “extreme capsule fascicle” instead, though other tracing studies show occipital-to-frontal fibres that resemble it. [1]
Its role is still debated. Electrical stimulation along it during awake brain surgery made people name pictures with a wrong word of related meaning, tying it to word meaning; newer evidence points to a broader role in cognitive control, reaching attention, reading, memory and recognising emotions. [1]
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.