Where is the inferior longitudinal fasciculus, and what does it join?
The inferior longitudinal fasciculus (ILF) is a long association bundle running along the lower side of one hemisphere, joining the occipital lobe at the back to the front of the temporal lobe. It runs along the outer and lower wall of the lateral ventricle. [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 longitudinal fasciculus joins.
The brain starts seen from the left, a little from below and behind, so the occipital lobe at the back and the underside of the temporal lobe both show. One end is lit in blue (the occipital lobe), the other in orange (the temporal 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, nor for the front of the temporal lobe alone, so the whole temporal lobe is lit, on both sides; the bundle ends only in its front part. The fibres between the two ends, beside the lateral ventricle, are not lit. [3][1]
The two ends: which colour is which
Back end: the occipital lobe, lit in blue: the occipital lobe, on both sides of the brain.
Behind, its fibres start in the extrastriate cortex of the occipital lobe, the visual cortex outside the primary visual area: the superior, middle and inferior occipital gyri, the lingual gyrus, the cuneus, and the fusiform gyrus where the occipital and temporal lobes meet. [1][2]
Front end: the front of the temporal lobe, lit in orange: the temporal lobe, on both sides of the brain.
In front, they end in the anterior temporal regions, on the lower surface of the front of the temporal lobe; its lingual branch reaches the front of the middle temporal gyrus, its cuneal branch the inner temporal gyri. [1][2]
The bundle runs between the blue and the orange parts; its fibres are not drawn.
It is the white-matter backbone of the ventral visual stream, the route out of the occipital lobe tied to recognising what things are. [1][2]
Dissection finds four branches: fusiform (the fusiform gyrus to the front of the temporal lobe), dorsolateral occipital (the superior, middle and inferior occipital gyri to the same region), lingual (the lingual gyrus to the front of the middle temporal gyrus) and a minor cuneal branch (the cuneus to the inner temporal gyri). [1][2]
The Dejerines described it in 1895 as a sharply bent gutter of fibres round the lower and outer side of the lateral ventricle. Some later authors denied it existed, because results in non-human brains were unclear, until diffusion imaging confirmed it as a constant pathway in humans. [2][1]
It is layered and carries signals both ways. Studies tie it to object, face and place processing, reading, word meaning, emotion processing and visual memory; a working right ILF appears crucial for recognising faces efficiently. [2][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.