• 21 parts
  • Checked September 2026

Inner Ear Diagram

The balance side of the inner ear: canals, ducts, sacs, and the sensors inside them.

Inner Ear Diagram

Name Date

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
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Write the name of each numbered part.Answer key

  1. Cochlea
  2. Vestibule
  3. Anterior semicircular canal
  4. Posterior semicircular canal
  5. Lateral semicircular canal
  6. Semicircular ducts
  7. Utricle
  8. Saccule
  9. Macula
  10. Oval window
  11. Round window
  12. Vestibular nerve
  13. Cochlear nerve
  14. Ampulla
  15. Cupula
  16. Endolymph
  17. Otoliths
  18. Otolithic membrane
  19. Hair cells
  20. Stereocilia
  21. Supporting cells

Drawn for this site on 2026-09-30 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 ear

All 21 parts on the diagram

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The whole inner ear 13

  1. Cochlea Sound is turned into nerve signals here.
  2. Vestibule It holds the utricle and the saccule.
  3. Anterior semicircular canal One of the two upright canals. It picks up the head nodding.
  4. Posterior semicircular canal It picks up the head tilting toward a shoulder.
  5. Lateral semicircular canal It picks up the head turning side to side, like saying no.
  6. Semicircular ducts They are filled with endolymph, which lags behind when the head turns.
  7. Utricle The semicircular ducts open into it. With the saccule it senses the position of the head.
  8. Saccule With the utricle it senses the position of the head.
  9. Macula Hair cells and supporting cells under the otolithic membrane. The third drawing enlarges it.
  10. Oval window Vibrations from the middle ear enter here.
  11. Round window Its membrane bulges out and in as fluid in the cochlea moves.
  12. Vestibular nerve It joins the cochlear nerve to form the vestibulocochlear nerve.
  13. Cochlear nerve It joins the vestibular nerve to form the vestibulocochlear nerve.

Inside the balance organs 8

  1. Ampulla Its hair cells respond when the head turns.
  2. Cupula When the head turns, the fluid lags behind and pushes it over. That bends the hairs.
  3. Endolymph It fills the membranous labyrinth. A second fluid, perilymph, lies outside it, against the bone.
  4. Otoliths Crystals of calcium carbonate that make the membrane under them top-heavy.
  5. Otolithic membrane It slides over the macula when the head tilts, bending the stereocilia.
  6. Hair cells Bending the tuft changes the signal the cell sends along the nerve.
  7. Stereocilia They stand in a row from tallest to shortest.
  8. Supporting cells They surround the hair cells in the macula.

How this list was compiled: Every name and detail checked on 2026-09-30 against OpenStax Anatomy and Physiology 2e, section 14.1 Sensory Perception (hearing and equilibrium: cochlea, vestibule, oval and round windows, utricle, saccule, macula, hair cells, support cells, stereocilia, otolithic membrane, otoliths, semicircular canals, ampulla, cupula), https://openstax.org/books/anatomy-and-physiology-2e/pages/14-1-sensory-perception, and against Wikipedia, Inner ear, Semicircular canals and Utricle (ear), text only. The names OpenStax does not print (lateral semicircular canal, semicircular ducts, endolymph, vestibular nerve, cochlear nerve) were confirmed in Wikipedia and in a second text: TeachMeAnatomy, The Inner Ear, https://teachmeanatomy.info/head/organs/ear/inner-ear/, or Gray, Anatomy of the Human Body, 20th edition, 1918 (public domain), https://archive.org/details/anatomyofhumanbo00grayrich. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; nothing traced. Licence: own work

How it works

The inner ear is a bony labyrinth with a softer set of ducts and sacs inside it. The first drawing shows the whole of it; the next two open an ampulla and enlarge a macula, where balance is sensed.

Read the full guide

Three drawings, from the outside in

Numbers 1 to 13 are on the whole inner ear: the cochlea, the vestibule, the three semicircular canals and the ducts inside them, the utricle and saccule, the two windows and the two nerve branches. Numbers 14 to 16 are in an ampulla cut open, where the cupula stands in the endolymph. Numbers 17 to 21 are in a macula: the otoliths, the otolithic membrane, the hair cells, their stereocilia and the supporting cells.

  • Canal is the bone; duct is the soft tube inside it. Likewise the vestibule is bone, and the two sacs lie inside it.
  • The semicircular canals sense the head turning; the utricle and saccule sense the position of the head.

Questions and answers

What are the semicircular ducts?

Three soft tubes of the membranous labyrinth, one inside each bony semicircular canal. They are filled with endolymph, and each has a swelling at one end, the ampulla, where hair cells sense the head turning.

What is the difference between the semicircular canals and the semicircular ducts?

The canals are the three bony loops of the labyrinth: anterior, posterior and lateral. The ducts are the membranous tubes that run inside them. Perilymph fills the canal around each duct; endolymph fills the duct.

What is the otolithic membrane?

A layer of gel that lies over the macula of the utricle and of the saccule, with crystals of calcium carbonate, the otoliths, on top. When the head tilts, it slides and bends the stereocilia of the hair cells under it.

What does the cupula do?

The cupula is a jelly-like cap in each ampulla that the stereocilia reach into. When the head turns, the fluid in the duct lags behind and pushes the cupula over, which bends the stereocilia.

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