Cranial nerves Aygul Shafigullina - PowerPoint Presentation

Slide1

Cranial nerves

Aygul

Shafigullina

Department of Morphology and General Pathology

Slide2

Organization of the nervous system

1.

Central

Nervous

System

(

CNS

)

a. Brain

b. Spinal cord

2.

Peripheral Nervous System

(

PNS

)

a. Peripheral nerves

b. Ganglia

Slide3

The peripheral nervous system

is subdivided into the

Somatic nervous system

Autonomous

(vegetative) nervous system

Sensory:

General:

Tactile

Pain

Pressure

Vibration

Temperature

2) Specific:

Vision

Hearing

Smell

Taste

Equilibrium

Motor:

-

Striated skeletal muscles

Parasympathetic:

Smooth muscles

of internal organs

Exocrine glands

Sympathetic:

Smooth muscles of the blood vessels

Piloerector

(erector muscles of hairs)

Sweat glands

Slide4

Effects of the ANS

Slide5

Functional classification of the ANS

Slide6

The Autonomic Nervous System (ANS) Controls the Body's Internal Environment in a Coordinated Manner

Slide7

In the ANS there are

2 nerves

between the central nervous system (CNS) and the organ.

The nerve cell bodies for the second nerve are organized into

ganglia

:

Slide8

Cranial Nerves Contain Sensory, Motor and

Parasympathetic

Fibers

Slide9

There are 12 Pairs of Cranial Nerves

The 12 pairs of cranial nerves emerge mainly from the ventral surface of the brain

Most attach to the

medulla, pons or midbrain

They leave the brain through various fissures and foramina of the skull

Slide10

Consequence of the answer

Name of the cranial nerve (English and Latin), number.

Nature (sensory, motor, parasympathetic, mixed).

Nuclei: names, projection to the brain (on rhomboid fossa), nature.

Emerge from the brain, where they leave the skull.

Passes of the nerves

Region of the innervation.

Slide11

Cranial nerves:

I –

O

lfactory

II –

O

ptic

III –

O

culomotor

IV –

T

rochlear

V –

T

rigeminal

VI –

A

bducens

VII –

F

acial

VIII –

V

estobulocochlear

IX –

G

lossopharyngeal

X –

V

agus

XI –

A

ccessory

XII –

H

ypoglossal

Slide12

Memory devices for learning the names of the 12 Cranial Nerves

O

n

O

ld

O

lympus's

T

owering

T

ops

A

F

inn

A

nd

G

erman

V

iewed

S

ome

H

ops

O

h,

O

h,

O

h,

T

o

T

ouch

A

nd

F

eel

V

ery

G

ood

V

elvet,

AH

!

The first letters (bold) match up with the first letters of the cranial nerves (for the second phrase use Vestibulocochlear instead of Auditory and plain Accessory instead of Spinal Accessory)

Slide13

Consequence of the answer

Name of the cranial nerve (English and Latin), number.

Nature (sensory, motor, parasympathetic, mixed).

Nuclei: names, projection to the brain (on rhomboid fossa), nature.

Emerge from the brain, where they leave the skull.

Passes of the nerves

Region of the innervation.

Slide14

Cranial Nerves Mediate 5 Special Senses: Smell, Vision, Hearing, Taste, Equilibrium

Smell

:

nerve

I (

Olfactory

)

Vision

:

nerve

II (

Optic

)

Hearing

:

nerve

VIII (

Auditory

part

)

Equilibrium

:

nerve

VIII (

Vestibular part

)

Taste: nerves

VII, IX, X (minor) (Facial, Glossopharyngeal,

Vagus

)

Slide15

Most of the Nerves Carry Somatic (Skin & Muscle) Sense

The trigeminal (V)

is the sensory nerve for the face

The nerves which are primarily motor also have fibers for muscle sense (proprioception): III, IV, VI, VII, XI, XII

Slide16

Three Nerves Are Concerned With Eyeball Movements

Oculomotor (III):

superior rectus, medial rectus, inferior rectus, inferior oblique

Trochlear (IV)

: superior oblique

Abducens (VI)

: lateral rectus

Slide17

Several of the Nerves Innervate Other Skeletal Muscles

The Facial nerve (VII)

controls the muscles of facial expression

The Spinal accessory (XI)

stimulates the trapezius and sternocleidomastoid muscles

Chewing muscles (masseter, temporalis) are innervated by the

Trigeminal (V)

Speech muscles (larynx) are under control of the

Vagus

(X)

The Hypoglossal (XII

) moves the tongue

Slide18

Slide19

Four of the Nerves Carry Parasympathetic Fibers

Oculomotor (III):

innervates iris constrictor (causes pupil constriction); also controls ciliary muscle (focuses the lens)

Facial (VII)

and

Glossopharyngeal (IX):

stimulate salivary glands to secrete

Vagus (X):

the major nerve of the parasympathetic system: goes to most visceral organs (heart, lungs, kidneys, liver, stomach, intestines)

Slide20

Consequence of the answer

Name of the cranial nerve (English and Latin), number.

Nature (sensory, motor, parasympathetic, mixed).

Nuclei: names, projection to the brain (on rhomboid fossa), nature.

Emerge from the brain, where they leave the skull.

Passes of the nerves

Region of the innervation.

Slide21

NB!

Sensory portion:

1

st

sensory neurons are in

sensory ganglion

(outside CNS)!

Exceptions:

- CN I and CN II develop from anterior brain vesicle (telencephalon).

- CN I and CN II have no sensory ganglion!

1

st

sensory neurons

are:

mucous membrane of the nasal cavity (CN I)

retina (CN II)

Parasympathetic portion

– 2 neurons:

1

st

neuron

– nucleus in CNS

2

nd

neuron

–

parasympathetic ganglion

:

g.

ciliare

(CN III)

g.

oticum

(CN IX)

g.

pterygopalatinum

(CN VII)

g.

submandibulare (CN VII)They are only parasympathetic! No sensory neurons!

Cranial nerves

Slide22

Cranial Nerve I - Olfactory Nerve

(

Nervus

olfactorius

)

Slide23

Olfactory

neuroepithelium

–

1

st

neuron

cell body in the nasal mucosa!

18-20 nerves ascend through

the cribriform plate

Olfactory bulb

– 2

nd

neurons cell bodies

Axons of the

2

nd

neurons

form

Olfactory tract

Olfactory area of the cortex

:

4

th

neuron

gyrus

parahippocampalis

, uncus

Primary olfactory regions

:

3

rd

neuron

1)

trigonum

olfactorium

; 2)

substantia

perforata anterior; 3) septum pellucidum

Cranial Nerve I - Olfactory Nerve

Slide24

Areas of the rhinencephalon

Medial olfactory area

- located in the

septal

region of the

medial surface of the frontal lobe

.

Via its connections with

the limbic system

, this area is thought to mediate the emotional response to odors.

Intermediate olfactory area

- located beneath

the olfactory

trigone

.

Lateral (primary) olfactory area

- consists of the cortex of the

uncus and the anterior part of the

parahippocampal

gyrus

(entorhinal area). Most of the axons of the olfactory tract project here.

Slide25

The

vomeronasal

organ

(

VNO

,

Jacobson's organ

)

an auxiliary olfactory sense organ that is found in many animals.

close to the

vomer

and nasal bones.

detect chemical stimuli, mainly

pheromones

(chemical messengers that carry information between individuals of the same species).

Olfactory

neuroepithelium

–

1

st

neuron

cell body in the nasal mucosa!

Accessory Olfactory bulb

–

2

nd

neurons

cell bodies

Amygdala

and

the

stria

terminalis

Hypothalamus

Slide26

Cranial Nerve II - Optic Nerve

(

Nervus

opticus

)

Slide27

Photons of light passing through the cornea and aqueous humor and entering the pupil travels through the lens and vitreous body to reach the retina at the back of the eye.

Cranial Nerve II - Optic Nerve

Slide28

Nature: - only a special sensory component (vision)

Cranial Nerve II - Optic Nerve

1

st

neuron

Photoreceptor cells:

Rod and Cone Cells

2

nd

neuron –

Bipolar cells

3

rd

neuron

-

Ganglion cells,

whose axons form

optic nerve

Slide29

Optic nerve

Optic chiasm

(only medial portion of the fibers cross the midline)

Subcortical vision centers: 4

th

neurons

Corpus

geniculatum

laterale

Pulvinar

cells of thalamus

Colliculi

superiores

tecti

mesencephali

Axons pass through crus posterior

capsulae

internae

and form

radiatio

optica

(

geniculocalcarine

tract, fasciculus of

Gratiolet

, #5)

Cortical vision centers: 5

th

neuron

- Laterally to

sulcus

calcarinus

Slide30

NB! The axons of the optic radiation fan out to pass above and lateral to the inferior horn of the lateral ventricles enroute

to the visual cortex. The fibers that course anteriorly toward the pole of the temporal lobe before turning posteriorly are referred to as

Meyer's loop

.

Slide31

Optic nerve

Chiasma

opticum

Optic tract

Corpus

geniculatum

laterale

Radiatio

optica

Sulcus

calcarinus

Left

Right

Slide32

Slide33

Extraorbital muscles of the eye

Voluntary skeletal muscles

– somatic motor innervation

Slide34

Slide35

m. obl. inferior

m. obl. inferior

m. rectus superior

m. rectus superior

m. rectus lat.

m. rectus lat.

m. rectus med.

m. rectus med.

m. obl. superior

m. obl. superior

m. rectus inf.

m. rectus inf.

Slide36

Intraorbital

muscles of the eye

Smooth muscles – parasympathetic innervation

Slide37

Function of the

intraorbital

muscles

m. sphincter

pupillae

m.

ciliaris

Slide38

The somatic motor

component of CN III:

Nuclei

:

1) Nucleus

nervi

oculomotorii

2) Nucleus

impar

(nucleus

Perlia

)

The

parasympathetic

component of CN III (involved in the pupillary light and accommodation reflexes):

Nucleus:

-

Nucleus

accessorius

nervi

oculomotorii

(nucleus

Edinger-Westphal

–

Yacubovich

)

Cranial Nerve III - Oculomotor Nerve

(Nervus oculomotorius)

Slide39

Slide40

The Parasympathetic is the "Rest and Digest" Branch of the ANS

Parasympathetic nerves

come from the

cranial and sacral regions

of the CNS.

They have long preganglionic nerves which synapse at ganglia near or on the organ innervated

Postganglionic fibers reach the effector with sensory nerves, that give sensory innervation to the same effector

Slide41

Preganglionic fibers

Postganglionic fibers

Slide42

Intraorbital

muscles innervation

CN III

CN III

Sympathetic innervation

Slide43

CN III –

Oculomotor

nerve palsy

Paralysis of

m.levator

palpebrae

superior –

ptosis

of superior eyelid

Paralysis of

extraorbital

muscles:

m.rectus

superior

m.rectus

medialis

m.rectus

inferior

m.obliquus

inferior

m.levator

palpebrae

superior

Result

– eye is moved laterally and downwards – action of

m.rectus

laterlis

Paralysis of

intraorbital

muscles:

m.

ciliaris

m. sphincter

pupillae

Result

–

mydriasis

and no

accomodation

Slide44

Paralysis of…:

Nervus

oculomotorius

Nervus

abducens

Nervus

trochlearis

Slide45

Paralysis of…:

Nervus

oculomotorius

Nervus

abducens

Nervus

trochlearis

Slide46

Cranial Nerve V - Trigeminal Nerve

(

nervus

trigeminalis

)

The largest of the cranial nerves and contains both sensory and motor fibers.

Slide47

Nuclei of the trigeminal nerve (CN V)

Sensory nuclei:

n.

mesencephalicus

n.

pontinus

(main sensory nucleus)

n.

spinalis

Motor nucleus:

Nucleus

nervi

trigemini

1

st

sensory neurons:

- Trigeminal ganglion

Slide48

1

st

sensory neurons

- Trigeminal ganglion

The sensory root carries the

trigeminal ganglion

which consists of the cell bodies of the sensory axons and lies in a depression on the petrous part of temporal bone.

Slide49

The sensory root divides into

three large branches

:

The Ophthalmic (V1)

is the smallest division of the trigeminal nerve and is

entirely sensory

Maxillary

(V2)

is

entirely sensory

Mandibular (V3)

is

both sensory and motor

Slide50

Slide51

CN V – The Ophthalmic division

- traverses the cavernous sinus and enters the orbit via the

superior orbital fissure

Only sensory!

Sensory message from tear gland, upper eyelid, the mucosa of the nasal cavity and the cornea.

Slide52

The frontal nerve

lies just under the roof of the orbit and divides into supraorbital and

supratrochlear

nerves which emerge from the orbit and supply the front of the scalp.

Trigeminal nerve (CN V)

Slide53

The lacrimal nerve

lies laterally and supplies the eyelids and face.

It also carries parasympathetic fibers from the

pterygopalatine

ganglion to the lacrimal gland.

Trigeminal nerve (CN V)

the

pterygopalatine

ganglion

Slide54

Trigeminal nerve (CN V)

The

nasociliary

nerve

crosses the optic nerve and runs along the medial wall of the orbit to emerge onto the face as the

infratrochlear

nerve.

–It gives off the

ethmoidal

nerves

to the

ethmoidal

sinuses and

–the

long

ciliary

nerves

to the eye which carry sensory fibers from the cornea and sympathetic fibers to the dilatator

pupillae

.

Slide55

This leaves the cranial cavity through the

foramen

rotundum

and enters the

pterygopalatine

fossa

.

CN V – The maxillary division

Only sensory!

Slide56

Slide57

Slide58

Slide59

–

the

zygomatic

nerve

leaves

the

pterygopalatine

fossa

via

the

inferior orbital

fissure

–

the great

and

lesser palatine nerves

to the hard and soft palates,

–

the

sphenopalatine

nerve

to the nasal cavity and thence via the nasal septum, to the

incisive fossa

to supply the hard palate.

–

the posterior superior dental nerve

enters the back of the maxilla and supplies the teeth.

CN V – The branches of the maxillary nerve

Only sensory!

Slide60

CN V – The branches of the maxillary nerve

The maxillary nerve leaves the

pterygopalatine

fossa via the

inferior orbital fissure

, travels in the floor of the orbit where it gives

the middle

and

anterior superior dental nerves

, and emerges onto the face through the

infraorbital

foramen

as the

infraorbital

nerve

.

Only sensory!

Slide61

CN V – The mandibular division

This leaves the cranial cavity through the

foramen

ovale

and immediately breaks up into branches.

Innervate the skin and teeth of the lower jaw for

sensation

.

Innervate

musticatory

muscles (

somatic motor

):

m.masseter

m.temporalis

m.pterygoideus

medialis

m.pterygoideus

lateralis

Other muscles:

m.

mylohyoideus

venter anterior

musculi

digastrici

Slide62

The mandibular division contains both motor and sensory branches.

CN V – The mandibular division

Slide63

The mainly sensory

inferior alveolar nerve

, which enters the

mandibular foramen

to supply the teeth before emerging onto the face as

the mental nerve.

•This nerve does have one

motor branch

,

the

mylohyoid

nerve

, which supplies the

mylohyoid

and anterior belly of the digastric.

CN V – The branches of the mandibular nerve

Slide64

The lingual nerve lies close to the mandible just behind the third molar and then passes forwards to supply the tongue.

It is joined by the

chorda tympani (CN VII)

which carries taste fibers from the anterior two-thirds of the tongue and parasympathetic

secretomotor

fibers to the submandibular and sublingual salivary glands.

CN V – Lingual nerve

General sensitivity for the anterior two-thirds of the tongue

Slide65

The auriculotemporal

nerve

supplies

sensory

fibers to the side of the scalp.

– It also carries parasympathetic

secretomotor

fibers, which have synapsed in

the

otic

ganglion

, to the parotid gland.

The

buccal

nerve

carries

sensory

fibers from the face.

There are

muscular branches

to the muscles of mastication, including the deep temporal nerve which supply temporalis.

CN V – The mandibular division

Slide66

Valleix

points

- areas, where the Trigeminal nerve arise on the surface of the skull – areas to check CN V neuralgia

Slide67

Damage to Cranial Nerves Causes Many Medical Problems

Anosmia

(loss of smell): sometimes caused by fractures which damage the cribiform plate. This damages the Olfactory nerve as it passes through the plate.

Bell's Palsy

: paralysis of the muscles of facial expression on one side. Caused by inflammation of the Facial nerve.

Tic douloureux

: severe facial pain caused by inflammation of the trigeminal nerve.

Blindness:

caused by damage to optic nerve. Degree of blindness depends upon the location of the damage.