The Human Inner Ear

How it was built, what is exact, and where the anatomy comes from.

Scale & placement

The Inner ear · + Middle ear · In the head control zooms between three true-to-scale levels. The labyrinth is about 20 mm across; the head around it is about 200 mm — a factor of ten. The right labyrinth is placed 38 mm from the midline, at the level of the external acoustic meatus and roughly 30–35 mm medial to it, inside the petrous temporal bone. The head, skull, brain and outer ear are stylised references built at correct proportions, not scan data; they exist to answer “where in the head is this?”, not to be dissected.

The geometry

Nothing here is a scanned or downloaded mesh. Every structure is generated in the browser from parametric equations at true millimetre scale, for a right ear, in the anatomical frame +X lateral, +Y superior, +Z anterior. The cochlea is a logarithmic spiral of 2.65 turns with a tapering canal; the three semicircular canals are arcs in three mutually perpendicular planes, with the lateral canal tilted 25–30° nose-up and the vertical canals at ~45° to the sagittal plane; the anterior and posterior canals merge into a single common crus, giving five — not six — openings into the vestibule.

What is exact and what is schematic

Exact: overall proportions, canal radii and orientations, cochlear turn count and taper, the position of the oval and round windows, the direction the modiolus and CN VIII point, and the tonotopic frequency map (Greenwood function, f = 165.4 (10^2.1x − 0.88) over a 35 mm partition).

Deliberately exaggerated for legibility: the basilar membrane, Reissner’s membrane, the tectorial membrane, the stria vascularis and the membranous ducts are drawn thicker than life — several are only microns thick in reality. True dimensions are always given in each structure’s Key data. The two inset drawings (cochlear cross-section, organ of Corti) are schematic histological diagrams, not renderings of the 3D mesh.

Sources

• StatPearls / NCBI Bookshelf — Neuroanatomy of the Ear; Anatomy, Organ of Corti; Endolymph; Presbycusis; BPPV; Otosclerosis; Labyrinthitis; Acoustic Neuroma; Internal Auditory Canal
• NCBI Bookshelf — Neuroscience (Purves): The Otolith Organs; The Semicircular Canals; Two Kinds of Hair Cells in the Cochlea
• Kenhub — Internal ear anatomy; Vestibular system; Utricle and saccule; Vestibulocochlear nerve; Internal acoustic meatus
• TeachMeAnatomy — The Inner Ear
• Radiopaedia — Cochlea; Vestibular aqueduct; Enlarged vestibular aqueduct; Superior semicircular canal dehiscence
• Bradshaw et al., A Mathematical Model of Human Semicircular Canal Geometry (JARO, PMC2862918) — canal radii of curvature
• Massachusetts Eye and Ear Temporal Bone Registry — Anatomic Studies of the Human Cochlea — measured cochlear height, base width and duct length
• Greenwood, A cochlear frequency-position function for several species — the tonotopic map
• NIDCD — Ménière’s disease; Noise-induced hearing loss; Balance disorders
• GeneReviews — SLC26A4-related sensorineural hearing loss (Pendred syndrome / DFNB4)

Where the literature disagrees — cochlear height, outer hair cell counts, spiral ganglion neuron counts, canal lumen calibre — the panels give the range rather than a single figure.

Keyboard

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focus search

C

cutaway

G

cycle inner ear → middle ear → whole head

T

tonotopy map

L

labels

H

reset view

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step through a guided tour

Esc

deselect / close

Technical

Single self-contained HTML file — Three.js r185 (WebGL 2), OrbitControls and CSS2DRenderer, bundled inline with esbuild. No network requests, no external assets, no tracking; it runs offline from a local file. Geometry detail drops automatically on low-core touch devices.

Educational reference only — not a substitute for clinical training or medical advice.

Select a condition to jump to the structure it affects.