1. Vestibular Ocular Reflex (VOR) EXAM #2 CONTENT - Eye Movements and Binocular Vision Summer 2026

stretch receptors in the neck rather than by the vestibular apparatus

What is the cervico-ocular reflex initiated by?

to that of the VOR

Cervico-ocular reflex gives a response similar to what?

who have lost normal vestibular function (infection, trauma, congenital, etc)

Cervico-ocular reflex is only important in what patients?

This is an antibiotic that can knock out the RVOR system

What does streptomycin have to do with the VOR system?

in the inner ear; adjacent and continuous with the cochlea

Where is the vestibular apparatus located?

membranous structure filled with viscous endolymph

What is the vestibular apparatus?

-3 semicircular canals

-otolith

What does the vestibular apparatus consist of?

rotational acceleration

What do the 3 semicircular canals detect?

detect linear acceleration (often gravity)

What does the otolith detect?

2

The otolith organ consists of ____ functional bodies

-Utricle

-Saccule

What are the 2 functional bodies of the otolith organ?

horizontally

The utricle is ________ oriented

-horizontally translational acceleration

-shifts in gravity vector d/t tilt

What does the utricle respond to?

vertically

The utricle is ________ oriented

vertical translational acceleration

What does the saccule respond to?

Vestibular Apparatus (Pic)

Vestibular Apparatus (Pic)

macula

Forces in the utricle and saccule are sensed by the _______

crista

The macula of the utricle and saccule is analogous to the ______ of the semicircular canals

region of epithelium which contains a dense aggregate of hair cells

What is the macula of the utricle and saccule?

true

True or False:

Cilia of the hair cells of the utricle and saccule are much like those of the semicircular canals and contain kilocilium and stereocilia

otolithic membrane

Cilia extend into the ________

calcium carbonate crystals

What does the otolithic membrane contain?

origin of otoconia in BPPV

What is the importance of the otolithic membrane?

In the macula of the utricle and saccule, hair cells have a random orientation. Stimulate based on all different head movements

How are the kinocilium different in the utricle and saccule than in the semicircular canals?

Otolith Organ (Drawing)

Otolith Organ (Drawing)

Linear accelerations will move the macula and hair cells. Crystals give the otolithic membrane more mass and it can stay in one place with movements/accelerations. Otolithic membrane seems to move in the opposite direction of the macula/hair cells (causes shearing).

Why are calcium carbonate crystals important?

transient linear (translational) accelerations of the head and static head tilt

Shearing of the sensory hair cells with acceleration causes what?

It will slide and pull on the cilia, causing an increase or decrease in the firing rate

When the head translates, what happens to the otolithic membrane?

35ms

What is the latency for T-VOR movement?

R-VOR

Which is faster?

R-VOR or T-VOR

-sustained lateral tilts (head tilt to the shoulder)

-sustained fore-aft tilts (pitch forward or backwards)

-Side to side translations of the head

The utricle will respond best to what?

Responds best to up and down translations of the head

The saccule will respond best to what?

One example of an eye movement which results from the otolith organ; refers to cycloversion that accompanies tilt of the head, tilt head to left or right shoulder.

What is counter-rolling of the otolith organ?

Get a compensatory eye movement in the opposite direction

What happens with counter-rolling?

dynamic response is much better

Which response is better?

Dynamic or static counter-rolling

rotational acceleration

Semicircular Canals vs Otolith

What do the semicircular canals detect?

translational acceleration or static tilt (shift in the gravity vector)

Semicircular Canals vs Otolith

What does the otolith detect?

in the ampulla

Semicircular Canals vs Otolith

Where does detection occur in the semicircular canals?

utricle, saccule

Semicircular Canals vs Otolith

Where does detection occur in the otolith?

Crista

Semicircular Canals vs Otolith

Where is movement detected? Where do the hair cells reside in the semicircular canals?

macula of the utricle and saccule

Semicircular Canals vs Otolith

Where is movement detected? Where do the hair cells reside in the otolith?

stereocilia; kinocilium

Semicircular Canals vs Otolith

In the semicircular canals and in the otolith, each hair cell has multiple ____ and one ______

depolarization -- increased firing rate

Semicircular Canals vs Otolith

Bending of the stereocilia toward the kinocilium causes ______ of the hair cell in both the semicircular canals and the otolith

hyperpolarization -- decreased firing rate

Semicircular Canals vs Otolith

Bending of the stereocilia away from the kinocilium causes ______ of the hair cell in both the semicircular canals and the otolith

symmetrical (kinocilium on same side of each hair cell) and all respond to the same direction of flow

Semicircular Canals vs Otolith

What is the arrangement of kinocilium in the semicircular canals?

Variable orientation -- Different hair cells respond to forces in different directions

Semicircular Canals vs Otolith

What is the arrangement of kinocilium in the otolith?

into the cupula -- dome like structure

Semicircular Canals vs Otolith

Stereocilia and kinocilium extend where in the semicircular canals?

into the otolithic membrane

Semicircular Canals vs Otolith

Stereocilia and kinocilium extend where in the otolith?