1b Vestibular Systems Flashcards
What are the mechanical sensors of the vestibular system?
Canals and otoliths
What is the input signal for the vestibular system?
movement and Gravity
What are the outputs of the vestibular system?
ocular reflex
Postural control
Where are the utricle and the saccule located?
in the vestibule, joined by a conduit
What are the three semi-circular canals on each ear calld?
Anterior, posterior and lateral
What do the semicircular canals have on one side and what are they connected to?
They have an ampulla and connected to the utricle
What are the two otolith organs?
The utricle and the saccule
Where are the hair cells located on otolith organs?
Maculae
How are the maculae placed on the saccule?
Vertically
How are the maculae placed on the utricle?
horizontally
What type of movements do the utricles detect?
horizontal movements
What type of movements do the saccule detect>
up and down linear movements
What does the maculae contain?
Hair cells, gelatinous matrix and the otoliths
What are otoliths?
Carbonate crystals that help the deflection of hair
What detects linear movement and tilt?
otolith movement
Where are the hair cells of the semi circular canals located?
At the ampulla
What does the rest of the vestibular canal contain?
endolymph which is high in potassium
What is the crista of the ampulla?
where the hair cells are located
What is the cupula?
Structure which surrounds the hair cells of the ampullary crista which helps the hair cell movement
Which two planes for a 90 degree angle?
Anterior and posterior
What direction do the lateral canals go in?
Horizontal to the other canals
What shape are the canals?
Semi-circular
What type of acceleration do the semi-circular canals provide information on?
Angular acceleration
What causes the hair cells to depolarise?
movement of the lymph generated through movement of the head
What happens to the nerve discharge when the hairs move towards the kinocilium?
Generates depolarisation and increase in nerve discharge
What happens to the nerve discharge when the hairs move away from the kinocilium?
generates hyperpolarisation and a reduction in nerve discharge
Where do the primary afferents of the vestibular nerve end?
IN THE VESTIBULAR NUCLEI IN THE PONS
What are the functions of the vestibular system?
Detect and inform about head movements
Keep images fixed in the retina during head movements
balance
What is the Vestibulo-Ocular Reflex?
When a quick movement of the head results in the eyes still focusing on the object
Keeps images fixed in the retina
What is the vestibulo Spinal reflex?
A reflex when the body falls to keep head up
What eye movements does the VOR (Vestibular Ocular Reflex) result in?
Eye movement in the opposite direction to head movement but same velocity and amplitude
How are vestibular disorders characterised?
by timing and laterality
What are the main complaints of Acute and unilateral vestibular disorders?
Imbalance, Dizziness, vertigo and naseua
What are the main complains of Slow progression and unilateral (or any bilateral) vestibular disorders?
Imbalance and nausea - no vertigo
What is Vestibular neuritis?
inflammation of the vestibular organ
what is affected in peripheral vestibular disorders?
vestibular organ and/or 8th cranial nerve
What is affected in central vestibular disorders?
CNS (Brainstem/cerebellum)
What are some examples of peripheral vestibular disorders?
Vestibular neuritis
benign Paroxysmal Positional vertigo
meniere’s disease
What are some examples of central vestibular disorders?
Stroke
MS
Tumours
What is BPPV?
benign Paroxysmal Positional Vertigo = When the crystal balls become dislodged
What are the red flag symptoms for vestibular disorders?
Headache
gait problems
hyperacute onset
hearing Loss
Prolonges sympoms
What is eye skew?
When you cover one eye, the eye then returns to the normal position as it was not in it before
What are acute balance disorders?
Vestibular neuritis
stroke
What are some examples of intermittent balance disorders?
benign Paroxysmal Positional vertigo
What are some examples of recurrent balance disorders?
Migraine
Menieres Disease
What are some examples of progressive balance disorders?
Schwannoma vestibular
Degerative Conditions
What is the HINTS test?
Head Impulse test
Nystagmus
Test of Skew deviation
What is the HINTS test used to do?
Differentiate between vestibular neuritis or stroke
What is the Dix Hallpike test used to do?
Diagnose benign paroxysmal positional vertigo
What condition?
Sudden intermittent vertigo crisis, felt like the room was spinning
When the patient sat down the spinning improved
benign paroxysmal positional vertigo
