Longitudinal fissureThe deep groove between the brain's two halves.
Genu of the corpus callosumThe bent front end of the corpus callosum. Its fibers fan forward into both frontal lobes.
Septum pellucidumA thin sheet between the two anterior horns. It runs from the corpus callosum to the fornix.
FornixA curved bundle of fibers from the hippocampus. This cut passes through its two columns.
Third ventricleThe narrow fluid space on the midline, between the two thalami.
Splenium of the corpus callosumThe thick back end of the corpus callosum. Its fibers fan backward into both occipital lobes.
Deep gray matter 5
Head of the caudate nucleusThe wide front end of the caudate nucleus. It bulges into the anterior horn of the lateral ventricle.
PutamenThe outer part of the lentiform nucleus.
Globus pallidusThe inner part of the lentiform nucleus, medial to the putamen.
ThalamusAn egg-shaped mass beside the third ventricle. The posterior limb of the internal capsule runs along its outer side.
ClaustrumA thin sheet of gray matter just inside the insula.
White matter bands 4
Anterior limb of the internal capsuleThe front arm of the V. It runs between the caudate nucleus's head and the lentiform nucleus.
Genu of the internal capsuleThe bend of the V, where the two limbs meet.
Posterior limb of the internal capsuleThe back arm of the V. It runs between thalamus and lentiform nucleus.
External capsuleA thin band of white matter between the putamen and the claustrum.
Edges and spaces 5
Cerebral cortex (gray matter)The folded outer layer of gray matter.
White matterThe mass of nerve fibers under the cortex.
InsulaA patch of cortex hidden deep in the lateral sulcus.
Anterior horn of the lateral ventricleThe front end of the lateral ventricle, in the frontal lobe.
Posterior horn of the lateral ventricleThe back end of the lateral ventricle, in the occipital lobe.
How this list was compiled: Every name checked on 2026-10-01 in at least two of these. (1) Wikipedia, English edition, Internal capsule, Corpus callosum, Septum pellucidum, Fornix (neuroanatomy), Third ventricle, Lateral ventricles, Longitudinal fissure, Insular cortex and Cerebral hemisphere, https://en.wikipedia.org/wiki/Internal_capsule. (2) Henry Gray, Anatomy of the Human Body (1918), The Fore-brain or Prosencephalon, https://www.bartleby.com/lit-hub/anatomy-of-the-human-body/4c-the-fore-brain-or-prosencephalon/. (3) Kenhub, Horizontal sections of the brain and Internal capsule, https://www.kenhub.com/en/library/anatomy/horizontal-sections-of-the-brain. (4) TeachMeAnatomy, The Cerebrum and The Basal Ganglia, https://teachmeanatomy.info/neuroanatomy/structures/cerebrum/. (5) Neuroscience Online, McGovern Medical School at UTHealth Houston, Section 3, Chapter 4, https://nba.uth.tmc.edu/neuroscience/m/s3/chapter04.html. 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
Twenty names to write in. The front of the brain points up the page, and each paired part is marked on one half only. Fifteen parts have a line; five are written on a shape with no line.
Read the full guide
Word bank for the blank axial section
Midline: longitudinal fissure, genu of the corpus callosum, septum pellucidum, fornix, third ventricle, splenium. Deep gray matter: head of the caudate nucleus, putamen, globus pallidus, thalamus, claustrum. White matter bands: anterior limb, genu and posterior limb of the internal capsule, external capsule. Edges and spaces: cerebral cortex, white matter, insula, anterior horn, posterior horn. Genu is written twice.
Five names with no line
In front of the V-shaped band, the oval: head of the caudate nucleus. In the open side of the V, a wedge in two pieces: putamen outside, globus pallidus inside. Behind the V, the large egg: thalamus. Under the folded rim, the wide field: white matter.
Two of the fifteen lines lie on the midline itself: one sticks out above the front of the brain, one runs back from the slit.
Questions and answers
What are the parts of the corpus callosum?
Four: the rostrum, the genu, the trunk or body, and the splenium. This cut meets it twice, so two separate bands cross the midline: the genu in front and the splenium behind.
What are the forceps minor and the forceps major?
Fibers of the corpus callosum on their way into the hemispheres. Those that curve forward, genu to frontal lobes, are the forceps minor; those that curve back from the splenium to the occipital lobes are the forceps major.
What is the extreme capsule?
A thin band of white matter between the claustrum and the insula. The external capsule is the band on the other side of the claustrum, against the putamen. Here the extreme capsule is the unnamed gap and takes no line.