Audition Part 2

Question 0

What two labyrinths make up the vestibular system? What are those labyrinths made up of?

Answer 0

The bony (vestibule and semicircular canals) and membranous labyrinths (semicircular ducts, saccule and utricle)

Question 1

Where is the vestibular system?

Answer 1

In the petrous portion of the temporal bone

Question 2

What secretes endolymph and where does it drain?

Answer 2

Secreted by cochlear duct, drained into dural sinuses via the endolymphatic duct

Question 3

What secretes perilymph and where is perilymph drained?

Answer 3

Perilymph is secreted by the periosteum, and drained into CSF via the perilymphatic duct

Question 4

What is Meniers disease? What are the symptoms and what is it caused by?

Answer 4

Excess production of endolymph creates pressure and causes malfunctioning signal transduction. Sympts include dizziness, vertigo, nausea, abnormal saccadic eye movements

Question 5

What are the three semicircular ducts/canals?

Answer 5

Anterior (superior), horizontal (lateral) and posterior

Question 6

What is the crista ampullaris? What is it made of?

Answer 6

It is the receptor in the ampulla of each semicircular canal. It contains a gelatinous mass called the cupula as well as receptor hair cells embedded within the cupula

Question 7

What two types of hair cell projections are in the cupula?

Answer 7

Stereocilia and one kinocilium per hair cell

Question 8

How does endolymph relay information about relative head motion?

Answer 8

As the skull turns, endolymph gains inertia within the semicircular canals, putting pressure on hair cells which relay signals about head motion

Question 9

What is the macula? Where is it? What is it made of?

Answer 9

Receptor system in the saccule and utricle. Contains epithelial supporting cells with receptor hair cells. Supporting cells produce the otoliths gelatinous layer. On top of the gelatinous layer is the otoliths, calcium carbonate stones

Question 10

In what planes of space are the macular of the saccule and utricle oriented?

Answer 10

The saccule is oriented in a vertical plane, the utricle is oriented in a horizontal plane

Question 11

When the Stereocilia are deflected towards the kinocilium, is the firing rate of the sensory neuron increased or decreased?

Answer 11

Increased

Question 12

Hair cell cilia are distorted by what two things?

Answer 12

Gravitational pull of the otoliths and inertia of the otoliths during movement

Question 13

Sensory vestibular neurons join which cranial nerve?

Answer 13

The vestibulocochlear nerve, CN VIII

Question 14

What are two common causes of vertigo?

Answer 14

Acoustic neuroma and Ménière’s disease

Question 15

What is acoustic neuroma?

Answer 15

Benign tumor pressing against the vestibulocochlear nerve and facial nerve. Symptoms: nausea, vomiting, ipsilateral deafness, tinnitus

Question 16

How is it that pressure on the vestibulocochlear nerve or vertigo can lead to nausea and vomiting?

Answer 16

Vestibular nuclei project to the solitary nucleus, a site of stomach afference

Question 17

What is benign paroxysmal positional vertigo?

Answer 17

Dizziness, vertigo, nausea imbalance due to dislodged otoliths from trauma, infection or degeneration with age

Question 18

Where do vestibular nuclei project to for postural control?

Answer 18

Thalamus and cortex

Question 19

Where do vestibular nuclei project to for eye movements?

Answer 19

Brain stem nuclei

Question 20

Where do vestibular nuclei project to for vascular control?

Answer 20

Autonomic centers

Question 21

Vestibular nuclei communicate with what lobe for reflex and precision?

Answer 21

The flocculonodular lobe of the cerebellum

Question 22

What is the vestibulo-ocular reflex for?

Answer 22

Tracking objects- movement of the head results in opposite movement of the eye

Question 23

What is the neural pathway of the vestibulo-ocular reflex?

Answer 23

Head moves left, causes movement in the horizontal semicircular canals. Vestibular nerve –> reticular formation –> Abducens and oculomotor nerve –> eyes move right.

Question 24

What does the VOR require for precision?

Answer 24

Vestibulo-cerebellar communication

Question 25

What is physiological nystagmus?

Answer 25

Normal part of the VOR system, rapid movement of the eye after tracking to keep up with the head

Question 26

What is pathological nystagmus?

Answer 26

Spontaneous rapid eye movements independent of head movement due to damage to one or more parts of the vestibular system

Question 27

What is the neural pathway for the vestibulo-sympathetic reflex?

Answer 27

Vestibular nuclei –>RVLM –> IML cell column of the spinal cord

Question 28

What does the vestibulo-sympathetic reflex do?

Answer 28

Enhances vasoconstriction during stress, postural syncope. Increased MAP, increased sympathetic control of skeletal muscle, kidney, blood vessels, but NOT GI. Increased skin vasoconstriction and sweating during nausea (eg. Sea sickness)

Question 29

How does information get from the vestibular nuclei to the vestibular cortex? What are 5 areas of cortex that are involved here?

Answer 29

Vestibular nuclei –> thalamus (VPL) –> cortex such as the temporal parietal junction (TPL), and parietal areas 3aV, 2V, 7 and the insula

Question 30

What is autoscopy? What is it caused by?

Answer 30

A condition in which one sees their own body in extrapersonal space, caused by incongruences among sensory inputs

Question 31

What are three types of autoscopy?

Answer 31

Autoscopic hallucination, heautoscopy, and out-of-body experience

Question 32

An out of body autoscopy is mainly due to a dysfunction in:

Answer 32

Strong vestibular dysfunction in the TPJ

Question 33

Autoscopic hallucination is usually a result in what dysfunction?

Answer 33

Minimal vestibular dysfunction

Question 34

Heautoscopy is usually due to what kind of dysfunction?

Answer 34

A mixture of strong vestibular dysfunction in the TPJ and minimal vestibular dysfunction

Question 35

How does the vestibular system regulate cerebral blood flow?

Answer 35

Increasing MAP via baroreceptors and vasoconstriction. Also increases cerebral blood flow by vasodilation cerebral vessels.

Question 36

The vestibular system dilates cerebral blood vessels via what two pathways?

Answer 36

Sympathetic inhibition: vestibular nuclei –> cerebellum–> RVLM –> inhibits constriction of cerebral vessels.
AND:
Vestibular nuclei –> solitary nucleus –> pteryyopalatine parasympathetic ganglion –> vasodilation of vessels