Brain Tracts Labeled: The White Matter of the Brain
The white matter of the brain in its three kinds of fiber: tap a ring to see what each joins.
Brain Tracts Labeled: The White Matter of the Brain
Name Date
Tap any tract to read, rename or leave it out
1 of 9
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Write the name of each numbered tract.Answer key
Corpus callosum
Anterior commissure
Corona radiata
Internal capsule
Short association fibers (U-fibers)
Superior longitudinal fasciculus
Cingulum
Uncinate fasciculus
Inferior longitudinal fasciculus
Drawn for this site on 2026-10-01 from plain geometry. Licence: own work.
Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a tract is answered.
Corpus callosumThe largest bundle of commissural fibers. It joins the two halves of the cerebrum.
Anterior commissureA small bundle of commissural fibers. It joins the two temporal lobes across the midline.
Projection fibers 2
Corona radiataA fan of projection fibers between the cortex and the internal capsule.
Internal capsuleA band of projection fibers between the deep gray nuclei. It carries fibers between the cortex and the brainstem and spinal cord.
Association fibers 5
Short association fibers (U-fibers)Short loops just beneath the cortex. Each joins one fold to the fold next to it.
Superior longitudinal fasciculusA long association bundle from the frontal lobe back over the insula. It reaches the parietal, occipital and temporal lobes.
CingulumAn association bundle inside the cingulate gyrus. It arches round the corpus callosum toward the temporal lobe.
Uncinate fasciculusA hook-shaped association bundle. It joins the frontal lobe to the front end of the temporal lobe.
Inferior longitudinal fasciculusA long association bundle along the bottom of the hemisphere. It joins the occipital lobe to the temporal lobe.
How this list was compiled: Every name checked on 2026-10-01 in at least two of these. (1) Henry Gray, Anatomy of the Human Body, 20th edition (1918), https://archive.org/details/anatomyofhumanbo1918gray. (2) Wikipedia, English edition, Superior longitudinal fasciculus, Uncinate fasciculus, Cingulum (brain), Inferior longitudinal fasciculus, Corona radiata and Anterior commissure, https://en.wikipedia.org/wiki/Superior_longitudinal_fasciculus. (3) Kenhub, White matter, Corpus callosum, Internal capsule and Anterior commissure, https://www.kenhub.com/en/library/anatomy/white-matter. The name U-fibers was also checked in (4) two journal abstracts at Europe PMC, Brain Connectivity (2011) and Cerebral Cortex (2020), https://europepmc.org/article/MED/22432953. Detail lines are in our own words. Licence: own work
The drawing: Drawn for this site on 2026-10-01 from plain geometry; nothing traced. Licence: own work
How it works
The white matter of the cerebrum is made of three kinds of fiber: commissural, projection and association. The first drawing cuts the brain from ear to ear; the second shows the long bundles of one half from the side.
Read the full guide
Cut ear to ear
Rings 1 and 2 cross the midline: the corpus callosum and the thin anterior commissure. Rings 3 and 4 run between the cortex and the parts below: the fan of the corona radiata narrows into the striped internal capsule. Ring 5 marks the short association fibers, U-shaped loops just under the cortex.
From the side
Four long association bundles stay inside one half of the brain. The superior longitudinal fasciculus is the outer arch and the cingulum the inner one. The uncinate fasciculus is the hook at the front, and the inferior longitudinal fasciculus runs along the bottom.
Commissural fibers cross to the other half. Association fibers stay in one half. Projection fibers join the cortex with lower parts.
Fasciculus is Latin for a small bundle.
Questions and answers
What are the three types of white matter tracts in the brain?
Association fibers, which join parts of the same half of the cerebrum; commissural fibers, which join the two halves; and projection fibers, which join the cortex with deeper parts of the brain, the brainstem and the spinal cord.
What is the largest white matter tract in the brain?
The corpus callosum. It is the largest bundle of commissural fibers and joins the left and right halves of the cerebrum. The anterior commissure is a much smaller bundle that also crosses the midline.
What is the difference between the corona radiata and the internal capsule?
They are two stretches of the same projection fibers. Near the cortex the fibers spread out as a fan, the corona radiata. Lower down they are packed into a narrow band between the deep gray nuclei, the internal capsule.
What do the association bundles join?
The superior longitudinal fasciculus joins the frontal lobe with the lobes behind it. The uncinate fasciculus joins the frontal and temporal lobes, the inferior longitudinal fasciculus the occipital and temporal lobes. The cingulum runs in the cingulate gyrus round the corpus callosum.