Usu, Nerves In The Head 2

Front 1

Name the 3 parts of the Ear

Back 1

External Ear - transferring sound
Middle Ear - transferring sound
Inner Ear - sensory receptors and vestibular system

Front 2

Where is the tympanic membrane located?

Which way does it face?

What are its two parts?

Back 2

Between the external and middle ear.

It faces downwards, forwards, and laterally.

It's two parts are:
1. Pars flaccids
2. Pars tensa - has fibrous core

Front 3

Roof of the Middle Ear:
What forms it?
What courses on/through it?

Back 3

It is formed by the tegmen tympani, a thin protion of the petrous temporal bone.
Courses on/through it: NOTHING

Front 4

FLoor of the Middle Ear:
What forms it?
What courses on/through it?

Back 4

Formed by: thin bone which separates the cavity from jugular fossa

Courses on/through it: Tympanic branch of IX pierces the floor enroute to tympanic plexus

Front 5

Medial Wall of the Middle Ear:

Contains: 6 things.

Back 5

1. Tympanic Plexus
2. Lesser Petrosal N.
3. Prominence of facial canal (CN.VII)
4. Prominence of lateral semicircular canal
5. Oval window - covered by stapes
6. Round window

Front 6

Posterior wall of the Middle Ear:

Contains: 4 things.

Back 6

Contians:
1. Auditus - an opening into the mastoid antrum. (communicates with mastoid air cells)
2.Facial Nerve
3. Chorda tympani nerve - arises from facial nerve
4. Pyrmaidal eminence - contains stapedius muscle

Front 7

Lateral wall of middle ear:

Contains:

Back 7

1. Formed inferiorly by tympanic membrane with the attached handle of the malleus.

2. Superiorly formed by bony lateral wal of the epitympanic recess

3.Chorda tympani - courses over the tendon of the tensor tympani

Front 8

Anterior wall of middle ear:

Contains:

Back 8

1. Opening of the canal of the tensor tympani

Front 9

3 bones of the middle ear:

Back 9

Malleus (hammer)

Incus (anvil)

Stapes (stirrup)

Front 10

Tensor Tympani
Origin
Insertion
Action
Innervation

Back 10

Tensor Tympani
Origin: cartilage of auditory tube

Insertion: Malleus

Action: tenses tympanic membrane and dampens its movements

Innervation: Mandibular N (V3)

Front 11

Stapedius
Origin
Insertion
Action
Innervation

Back 11

Stapedius
Origin: Oyramidal eminence

Insertion: Neck of stapes

Action: dampens movement of stapes

Innervation: Facial Nerve (CN.VII)

Front 12

2 Parts of the Inner ear

What is each filled with

Back 12

1. Bony labryinth - filled with perilymph

2. Membranous labryinth- filled with endolymph

Front 13

Components of the bony labrynth:

3 components

Back 13

1. Chochlea

2. Vesitbule - houses utricle and saccule

3. Semicircular canals

Front 14

Modiolus

Back 14

Spingy bone around which the choclea duct turns.

Center of the choclea.

Front 15

Vestibule

Back 15

Central chamber of the bony labyrinth.

Houses the utricle and saccule of the membranous labyrinth.

Front 16

Semicircular canals

Back 16

Part of the BONY LABYRINTH

Respond the rotational movements of the head.

House the semicircular ducts (membranous labyrinth)

Front 17

Semicircular ducts

Back 17

3 ducts - ant. post. lat.

Each contains and AMPULLA with a ridge of specialized epithelium, the CRISTA AMPULLARIS, which senses changes in the speed of angular movement of the head

Front 18

Crista Ampullaris

Back 18

Specialized epithelium which senses changes in the speed of angular movement of the head

Front 19

Utricle
Location:
Connected to:
Function:

Back 19

Located in bony vestibule and connected to semicircular ducts.

Contains a MACULA which senses gravity and horizontal and linear movement of the head.

Front 20

Saccule:
Location:
Connected to:
Function:

Back 20

Located in bony vestibule

Connected to cochlear duct

Function: senses gravity and verticle linear movement of the head

Front 21

5 Parts of membraneous duct

Back 21

Semicircular Ducts
Utricle
Saccule
Cochlear Duct
Endolymphatic Duct

Front 22

Choclear Duct
Location:
Contains:

Back 22

Location: Bony Choclea

Contains: Organ of corti - sound receptor

Front 23

Endolymphatic Duct:

Connects:
Function:

Back 23

Connects the utricle and saccule

Function: reabsorbs endolymph

Front 24

Meniere's disease
Cause:
Symptoms:

Back 24

Cause: excess of endolymph in inner ear
Symptoms: hearing loss, tinnitis, pain or pressure in affected ear.

Front 25

Cupula

Back 25

Gelatinous structure that rides on top of hair cells on top of the ampulla in the semicircular ducts.

Front 26

In semicircular ducts:

Bending hair cells TOWARDS cilium _____ cell membrane

Bending hair cells AWAY from cilium ______ cell membrane

Back 26

In semicircular ducts:
(change of speed of angular movement)

Bending hair cells TOWARDS cilium depolarizes cell membrane

Bending hair cells AWAY from cilium hyperpolarizes cell membrane

Afferent nerve fibers supplying the hair cells increase their rate of firing when hair cells are bent towards the cilium (depolarized)

Front 27

Otolithic membranes

Found: 2 places.

Back 27

Found in Utricle and Saccule

Gelatinous layers with crystals of calcium carbonate known as otoconia or otoliths

Front 28

Otoconia are more/less dense than endolymph?

Back 28

Otoconia are MORE dense than endolymph.

Front 29

Saccule senses ______ acceleration

Utricle senses _______ acceleration

Back 29

Saccule senses verticle acceleration

Utricle senses horizontal acceleration

The macula of the utricle is orientated perpendicular to the one in the saccule.

Front 30

Macula

Detects:

Back 30

Specialized epithelium in the utricle and saccule that have otolithic membranes.

Detects: LINEAR ACCELERATION

It is analogous to the crista ampullaris in the semicircular ducts.

Front 31

Crista Ampullaris detects:

Back 31

Crista Ampullaris detects ANGULAR ACCELERATION (which we perceive as angular velocity)

Front 32

Perilymph

Location:

Back 32

Between the outer wall of the membraneous labyrinth and the inner wall of the bony labyrinth.

Front 33

Endolymph has a high concentration of _____.

Back 33

Endolymph has a high concentration of POTASSIUM.

Front 34

Duct above the choclear duct.

Back 34

Scala vestibuli

Front 35

Duct below the choclear duct.

Back 35

Scala Tympani.

Front 36

Connects the scala vestibuli and the scala tympani.

Back 36

Helicotrema

Front 37

The scala vestibuli and the scala tympani both contain THIS fluid.

Back 37

Perilymph

Front 38

The choclear duct contains THIS fluid.

It is produced by_____.

Back 38

Endolymph

Endolymph is produced by the STRIA VASCULARIS

Front 39

The Scala Vestibuli connects to the ______ window.

Back 39

The Scala Vestibuli connects to the OVAL window.

Front 40

The Scala Tympani connects to the ______ window.

Back 40

The Scala Tympaniconnects to the ROUND window.

Front 41

INNER / OUTER hair cells receive 90-95% of the afferent fibers from the choclear nerve.

Back 41

INNER hair cells receive 90-95% of the afferent fibers from the choclear nerve.

Front 42

Path of Sound entering the Inner Ear.

Back 42

The stapes vibrates the OVAL WINDOW -->
The vibrations travel through the perilymph in the SCALA VESTIBULI--->
The sound wave causes displacement of the BASILAR MOVEMENT-->
The basilar membrane movement causes a sheering force on hair cell microvilli in contact with the TECTORIAL MEMBRANE -->
Sheering force changes the hair cell membrane potential -->
Choclear Nerve -->

Front 43

High frequency sounds cause displacement NEAR/FAR from the oval window.

Back 43

High frequency sounds cause displacement NEAR from the oval window.

Front 44

Low Frequency sounds cause displacement NEAR/FAR from the Oval window.

Back 44

Low Frequency sounds cause displacement FAR from the Oval window.

Front 45

Monitor position of the head with respect to gravity and linear acceleration.

Back 45

Hair cells of the MACULAE of the UTRICLE and SACCULE.

Front 46

Monitor changes in angular or rotational accelerations.

Back 46

Hair cells of the CRISTA AMPULLARIS of SEMICIRCULAR DUCTS.

Front 47

Sensory Epithelium of the Utricle and Saccule?

Back 47

Macula

Located on floor of Utricle - parallel to ground.

Located on the medial wall of saccule - perpendicular to ground.

Are mirror images of each other on each side of head.

Front 48

This membrane covers the Macula

Back 48

Otolithic membrane

Front 49

Detect angular or rotational acceleration of the head.

Back 49

Semicircular ducts.

Front 50

Snesory epithelium of the semicircular ducts.

Back 50

CRISTAE AMPULLARIS

Cristae ampullaris is covered by a gelatinous membrane called the CUPULA which responds to endolymph movement.

Front 51

Rotation of Head to the Left (Conterclockwise)

Back 51

Cilia in L.Duct are deflected towards the kinocilium causing a depolarization of hair cells in L.Horizontal Semicircular Duct

Cilia in the R.Duct are deflectedf away from the kinocilium caugin hyperpolarization of hair cells in the RHD.

This causes and INCREASE in firiing of L. Vestibular Nerve axons. (the side towards which the head is turned)

Front 52

Vestibulo-Ocular Reflex (VOR)
Function:

Back 52

VOR
Function: Allow gaze to remain fixed on a point in space during vertical and horizontal movements of the head.

Front 53

VOR:
Smooth (slow) eye movements

Back 53

As the head rotates, there is a slow phase eye movement in the opposite direction of motion that is times to coordinate with the head movement.

(Opposed to saccade - snap back)

Front 54

VOR:
Saccade

Back 54

VOR: SACCADE
When the eyes reach the edge of the orbit, they snap back rapidly in the direction of the rotation to reset to a new central position

(opposed to smooth eye movement)

Nysatagmus is named for the direction of the 'snap back' fast eye movement (in the direction of rotation)

Front 55

Nystagmus

Named for direction of FAST/SLOW eye movement?

Named according direction of _______.

Back 55

Nystagmus - repetitive slow and quick oscillation of the eye.

Named for the direction of FAST movement.

Named for direction of rotation

Front 56

Autonomic Pathway of VOR

Sensory Limb:

Efferent Limb:

Back 56

Autonomic Pathway of VOR

Sensory Limb:
Recpetors in semicircular ducts-->
Vestibular nerve --> vestibular nuclei
Cells in the vestibular nuclei project to extraocular cranial motor N. via MLF

Efferent Limb:
Extraocular cranial nerve motor nuclei (CN 3,4,6) project to extaocular eye muscles

Front 57

Barany Chair Rotation to the Right.

Stage 1:
Stage 2:
Stage 3:

Back 57

Barany Chair Rotation to the Right.

Stage 1:
i. Movement to R. causes hair cells in RHD to depolarize increasing action potential of R. Vestibular N.
ii. R. Vestibular N. stimulation produces a VOR resulting in a RIGHT nystagmus.

Stage 2:
After 25-30 sec of constant velocity, the endolymph reaches the same velocity as the head and semicircular ducts/cuplae are no longer deflected. NYSTAGMUS CEASES.

Stage 3: When the rotation is stpped, the endolymph continues to flow in direction of original rotation, bending the cupulae.
This produces a perceived rotation to the LEFT and produces a LEFT NYSTAGMUS.

Front 58

Optokinetic Nystagmus

Back 58

Produced if eyes are kept open while rotation in Barany Chair

Front 59

VOR Test (Doll's Eye Maneuver)

Back 59

Done on unconscious patient.

Lack of VOR indicated brain stem injury.

Front 60

Semilunar Ducts Contain:
Dilated Portion:
Sensory Receptor:
Capsule:

Sense:

Back 60

Semilunar Ducts Contain:

Dilated Portion: Ampulla
Sensory Receptor: Crista Ampullaris
Capsule: Cupula

Sense: Angular acceleration

Front 61

Utricle and Saccule Contain:
Sensory Receptor:
Covered by:

Sense:

Back 61

Utricle and Saccule Contain:
Sensory Receptor: Macula
Covered by: Otolithic Membrane

Sense: Linear Acceleration.

Front 62

Vestibular Pathway:

Back 62

Vestibular Nerve -->

Vestibular Nuclei -->
(4 Vestibular Nuclei are located in the flood of 4th ventricle lateral to sulcus limitans.

Vestibular Nuclei project to: -->
i. Spinal Cord (Med./Lat.Vest.Spinal Tracts)
ii. Extraocular nuclei - VOR (via MLF)
iii. Cerebellum

Front 63

A unilateral lesion of the vestibular systems produces:

Back 63

A unilateral lesion of the vestibular systems produces: an unapposed PUSH from the intact side causing the eyes, limbs, and body, to veer TOWARDS the lesioned side.

Front 64

In Past-Pointing a patients arm deviates _______ the side of the lesion.

Back 64

In Past-Pointing a patients arm deviates TOWARDS the side of the lesion.

Front 65

Caloric Stimulation of Vestibular Testing
Cold Water:

Hot Water:

Back 65

Cold Water: produces nystagmus to side OPPOSITE of injected ear.

Warm Water: Produces nystagmus towards SAME side as injected ear.