Vestibular Physiology

An interactive teaching atlas of vestibular physiology and the assessment of vertigo. Content synthesized from Dr Prahlada N.B's Physiology of the Vestibular System and peer-reviewed sources.

1

Introduction & Overview

What the vestibular system does, and why its physiology underpins the diagnosis of vertigo.

2

Evolution & Embryology of the Labyrinth

From the otic placode to the membranous labyrinth, and why a sealed endolymphatic compartment evolved.

3

Labyrinth Fluid Spaces & Ionic Homeostasis

Endolymph versus perilymph, the potassium gradient, dark cells, and the positive endolymphatic potential.

4

Hair Cells & Mechanoelectric Transduction

Type I and Type II hair cells, stereocilia and kinocilium, MET channels, and cosine tuning.

5

Semicircular Canals

Three orthogonal canals, the crista and cupula, coplanar push-pull pairing, and canal hydrodynamics.

6

Otolith Organs

Utricle and saccule, the maculae and striola, otoconia, and the detection of linear acceleration and tilt.

7

Vestibular Afferent Neurons

Spontaneous firing, regular versus irregular afferents, and bidirectional encoding of head motion.

8

Vestibulo-Ocular Reflex

The three-neuron arc, horizontal, vertical, and translational VOR pathways, the MLF, and INO.

9

Vestibulospinal Reflexes

Medial and lateral vestibulospinal tracts, the vestibulocollic reflex, and postural control.

10

Cerebellar Modulation & Central Integration

Flocculus and nodulus, Purkinje feedback, climbing fibres, the neural integrator, and central neuron types.

11

Visual–Vestibular Integration & Eye–Head Coordination

Multimodal convergence, gaze-shift VOR suppression, and adaptive plasticity.

12

Clinical Correlates & Vestibular Testing

How physiological lesions map onto vHIT, caloric testing, and VEMP, and onto the major vertigo syndromes.