• 18 parts
  • Checked October 2026

Diencephalon Labeling Quiz

Tap each named part of the diencephalon on the drawing, cut down the middle and from behind.

Diencephalon Labeling Quiz

Name Date

Tap the medial geniculate body

1 of 5

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Write the name of each numbered part.Answer key

  1. Thalamus
  2. Hypothalamus
  3. Third ventricle
  4. Pituitary gland
  5. Pineal gland
  6. Optic chiasm
  7. Mammillary body
  8. Infundibulum (pituitary stalk)
  9. Tuber cinereum
  10. Hypothalamic sulcus
  11. Interthalamic adhesion
  12. Anterior commissure
  13. Posterior commissure
  14. Pulvinar
  15. Medial geniculate body
  16. Lateral geniculate body
  17. Habenular trigone
  18. Stria medullaris

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 part is answered.

Next step Zoom out: the whole brain, lobes to brainstem

All 18 parts on the diagram

Show the list

Thalamus 5

  1. Thalamus The large egg-shaped mass that forms most of the diencephalon. It relays signals to and from the cerebral cortex.
  2. Interthalamic adhesion A band of gray matter joining the two thalami. It is cut across here.
  3. Pulvinar The bulging back end of the thalamus.
  4. Medial geniculate body A small oval swelling under the pulvinar. It is a relay on the hearing pathway.
  5. Lateral geniculate body An oval swelling at the outer side of the pulvinar. The optic tract ends in it.

Hypothalamus 6

  1. Hypothalamus The part of the diencephalon below the thalamus. It forms the floor and lower side walls of the third ventricle.
  2. Pituitary gland The gland that hangs from the hypothalamus on its stalk.
  3. Optic chiasm Where the two optic nerves meet and partly cross. It marks the front of the hypothalamus.
  4. Mammillary body One of two small round bodies in the ventricle floor. They mark the back of the hypothalamus.
  5. Infundibulum (pituitary stalk) The stalk from hypothalamus to pituitary gland.
  6. Tuber cinereum A swelling of the floor, behind the optic chiasm. The mammillary bodies lie behind it.

Epithalamus 4

  1. Pineal gland A small cone-shaped gland at the back of the third ventricle. It is part of the epithalamus.
  2. Posterior commissure A small band of crossing fibers below the pineal stalk. It is cut across here.
  3. Habenular trigone A small triangular area that holds the habenular nuclei. It lies ahead of the superior colliculus.
  4. Stria medullaris A thin band of fibers along the edge of the thalamus. It runs back to the habenular trigone.

Landmarks 3

  1. Third ventricle The narrow space between the two thalami. This view looks at its side wall.
  2. Hypothalamic sulcus The groove between the thalamus and the hypothalamus.
  3. Anterior commissure A bundle of crossing fibers in front of the fornix. It is cut across here.

How this list was compiled: Every name checked on 2026-10-01 in at least two of these. (1) Wikipedia, English edition, Diencephalon, Interthalamic adhesion, Habenular trigone, Pituitary gland, Medial geniculate nucleus and Lateral geniculate nucleus, https://en.wikipedia.org/wiki/Diencephalon. (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, Diencephalon, Thalamus and Hypothalamus, https://www.kenhub.com/en/library/anatomy/diencephalon. (4) Neuroscience Online, McGovern Medical School at UTHealth Houston, Section 4, Chapter 1, https://nba.uth.tmc.edu/neuroscience/m/s4/chapter01.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

The diencephalon is the part of the brain round the third ventricle: the thalamus, the hypothalamus, the epithalamus and the subthalamus. This brain diagram has the diencephalon labeled in two views, cut down the middle and from behind.

Read the full guide

What to look for in each view

The quiz names a part and you tap it. Cut down the middle, find the thalamus, the hypothalamus under the heavy curved line, and the third ventricle that shows round them. Then come the pituitary gland on its stalk, the pineal gland at the back, and the floor from front to back: optic chiasm, tuber cinereum, mammillary body. The view from behind shows the pulvinar, the two geniculate bodies under it, and the stria medullaris running back to the habenular trigone.

  • The hypothalamic sulcus is the dividing line: thalamus above it, hypothalamus below.
  • Two glands hang off the diencephalon: the pituitary below, on its stalk, and the pineal behind.

Questions and answers

What are the parts of the diencephalon?

The thalamus, the hypothalamus, the epithalamus and the subthalamus, arranged round the third ventricle. The thalamus is the largest. The epithalamus includes the pineal gland, and the pituitary gland hangs from the hypothalamus. The subthalamus is not drawn here.

How do you label the parts of the hypothalamus and surrounding structures?

Start at the third ventricle's floor. From front to back it holds the optic chiasm, the tuber cinereum with the infundibulum, and the mammillary bodies. The hypothalamic sulcus above parts the hypothalamus from the thalamus.

Where is the diencephalon in the brain?

In the center, round the third ventricle. It sits above the brainstem and below the corpus callosum and the cerebral cortex.

What is the difference between the medial and lateral geniculate bodies?

Both are small swellings under the back end of the thalamus. The medial geniculate body is a relay on the hearing pathway. The lateral geniculate body is a relay on the sight pathway, where the optic tract ends.

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