LAB
EXERCISE
11
CRANIAL
NERVES
Cranial Nerves
• Twelve pairs
of cranial
nerves
– That arise
from the brain
• Each nerve is
identified by a
Roman
number
– I through XII
– and a name
Cranial Nerves
•
Four Classifications of Cranial Nerves
1. Sensory nerves
**Carry somatic sensory information, including
touch, pressure, vibration, temperature, and pain
2. Special sensory nerves
**Carry sensations such as smell, sight, hearing,
balance
3. Motor nerves:
**Axons of somatic motor neurons
4. Mixed nerves:
**Mixture of motor and sensory fibers
Summary of Function of
Cranial Nerves
Figure 13.5b
Cranial
Nerves
• Four cranial nerves carry
parasympathetic fibers
that serve muscles and
glands
– Occulomotor (III)
– Facial (VII)
– Glossopharyngeal (IX)
– Vagus (X)
Cranial Nerves
• Cranial Nerves
–The 12 cranial nerve groups are
identified by:
–Primary function
–Origin
–Pathway
–Destination
Cranial Nerves
• Olfactory Nerves (I)
– Primary function:
• Special sensory (smell)
– Origin:
• Receptors of olfactory epithelium
Cranial Nerves
• Olfactory Nerves (I)
– Pathway:
• Olfactory foramina in cribriform plate of
ethmoid bone
– Destination:
• Olfactory bulbs
• To the olfactory tract
Cranial Nerve I - Olfactory Nerve
• Assesment
– Have patient smell different items
• Damage to the ethmoid bone
– Can cause anosmia
• Loss of smell
Cranial Nerves
• Optic Nerves (II)
– Primary function:
• Special sensory (vision)
– Origin:
• Retina of eyes
Cranial Nerves
• Optic Nerves (II)
– Pathway:
• Optic Canal of sphenoid bone
Cranial Nerves
• Optic Nerves (II)
– Destination:
• Diencephalon
via optic
chiasm
• Optic tracts
– Leading to
lateral
geniculate
nuclei
• Olfactory Lobe
Cranial Nerve II - Optic Nerve
• Assessment
– Test visual Acuity one eye at a time
• Snellen eye chart
– Test peripheral vision one eye at a time
• Cover one eye and have the patient look at
your nose.
• Move your finger to check superior and inferior
fields
• Damage to the orbits or diseases in
the nervous system can cause a loss
of vision.
• Anopia
– Ipsilateral blindness due to
sensory loss in the nerve
Cranial Nerves
• Oculomotor Nerves (III)
– Primary function:
• Motor (eye movements)
– Controls four of six eye-movement
muscles
– Origin:
• Midbrain
– Pathway:
• Superior orbital fissures of sphenoid
Cranial Nerves
• Oculomotor Nerves (III)
– Destination:
• Somatic motor
– Superior, inferior, and medial rectus muscles
– Inferior oblique muscle
– Levator palpebrae superioris muscle
Cranial Nerves
• Oculomotor Nerves (III)
– Visceral motor
• Parasympathetic Function
• Ciliary ganglion
Cranial Nerves
• Oculomotor Nerves (III)
– Destination:
• Visceral motor
(Parasympathetic)
– Intrinsic eye muscles
» Cilliary Muscle
**Accommodation
of the lens
» Circular Muscles
**Constriction of iris
» Radial Muscles
**Dilation of iris
Cranial Nerve III - Oculomotor
Assessment
- To test the patients pupils
*Use a penlight and mm ruler
- Check to see where eyelid falls on the pupil
Damages
*Causes Ptosis
– Drooping of eyelid
*Causes diplopia
– Double vision
*Trouble with eye movements
Cranial Nerves
• The Trochlear Nerves (IV)
– Primary function:
• Motor (eye movements)
– Origin:
• Midbrain
Cranial Nerves
• The Trochlear Nerves (IV)
– Pathway:
• Superior orbital fissure of sphenoid
– Destination:
• Superior oblique muscle
Cranial Nerve IV - Trochlear Nerve
Assessment
-Have patient follow your
finger while moving it to the
nose
Damages
*Causes
 Diplopia
 Paralysis
 Strabismus
*Lazy Eye
Cranial Nerves
• The Trigeminal Nerves (V)
– Primary function:
• Mixed Nerve
– Sensory
» Functions in
touch, pain, &
temperature
receptors of the
face
– Motor
» Innervates the
muscles of
mastication
Cranial Nerves
• The Trigeminal
Nerves (V)
• Largest cranial
nerves
• With three major
branches
–Ophthalmic
–Maxillary
–Mandibular
Cranial Nerves
• The Trigeminal
Nerves (V)
– Sensory
Innervation
– Semilunar ganglion
• Contains cell
bodies of
sensory neurons
Cranial Nerves
• The Trigeminal Nerves (V)
– Ophthalmic Branch (V1)
• Sensory innervation to:
–Orbital structures
–Nasal cavity
–Skin of forehead
–Upper eyelid
–Eyebrow
–Part of nose
Cranial Nerves
• The Trigeminal Nerves (V)
– Pathway:
• Ophthalmic Branch (V1)
– Superior Orbital Fissure
Cranial Nerves
• The Trigeminal Nerves (V)
– Origin:
• Maxillary Branch (V2)
• Sensory innervation to
– Lower eyelid
– Upper
» Lip
» Gums
» Teeth
– Cheek and nose
– Palate and part of
Cranial Nerves
• The Trigeminal Nerves (V)
– Pathway:
• Maxillary branch (V2)
–Foramen Rotundum
Cranial Nerves
• The Trigeminal Nerves (V)
• Mandibular Branch (V3)
– Sensory
innervation to:
» Lower
Gums
Teeth
Lips
» Palate
» Part of tongue
Lingual Nerve
Cranial Nerves
• The Trigeminal Nerves (V)
– Origin:
• Mandibular branch (V3)
• Motor innervation From
–Motor nuclei of pons
Cranial Nerves
• The Trigeminal Nerves (V)
– Destination:
• Motor nerves of Mandibular Branch
– Muscles of mastication
» Chewing
Cranial Nerves
• The Trigeminal Nerves (V)
– Pathway:
• Mandibular branch
– Foramen Ovale
Cranial Nerve V - Trigeminal
Assessment
*To test for pain, touch & tempersture
-Safety pin & hot and cold objects
*Corneal reflex
- Cotton wisk
*To test motor function
-Clench teeth and move jaw
side to side
Cranial Nerve V - Trigeminal
Damages
*Cause problems in chewing
*Loss of sensations of pain and
temperature
*Tic Douloureux
 Trigeminal Neuralgia
*Severe pain from damage
of maxillary and
mandibular nerves
Cranial Nerves
• The Abducens Nerves (VI)
– Primary function:
• Motor (eye movements)
– Origin:
• Pons
Cranial Nerves
• The Abducens Nerves (VI)
– Pathway:
• Superior orbital fissures of sphenoid
– Destination:
• Lateral rectus muscle
– Moves eye laterally
Cranial Nerve VI - Abducens
Assessment
Make a big x in the air and draw a
line through it.
**Observe for twitching or
nystagmus
Damages
*Cannot move eyeball laterally
*Nystagmus – “Dancing Eyes”
Cranial Nerves
• The Facial Nerves (VII)
– Mixed
– Sensory
– Motor
– Origin:
• Sensory
– Taste receptors on
anterior 2/3 of tongue
– Destination:
• Sensory
– Sensory nuclei of pons
Cranial Nerves
• The Facial Nerves (VII)
– Sensory Innervation
– Geniculate Ganglion
• Contains cell bodies
of sensory neurons
Cranial Nerves
• The Facial Nerves (VII)
–Origin:
• Motor
–Motor nuclei
of pons
–Destination
• Somatic Motor
–Muscles of
facial
Cranial Nerves
– Somatic Motor
– Facial nerve branches
• Temporal
• Zygomatic
• Buccal
• Mandibular
• Cervical branches
Cranial Nerves
• The Facial Nerves (VII)
– Destination
– Visceral motor
– Parasympathetic Function
» Pterygopalatine Ganglion
 Lacrimal gland
 Mucous Glands
» Submandibular Ganglion
Submandibular Glands
Sublingual Glands
SUBLINGUAL
Cranial Nerves
• The Facial Nerves (VII)
– Pathway:
• Internal acoustic
meatus to facial canals
• Then through the
stylomastoid foramina
Cranial Nerve VII - Facial Nerve
Assessment
-- To test for taste
**Place sugar(sweet) salt, vinegar(sour) & quinine(bitter)
on anterior 2/3 of tounge
-- To test for tearing
**Place ammonia near the eyes
-- To test for facial symmetry
**Have patient close eyes, smile, whistle and blow
Cranial Nerve VII - Facial Nerve
Damages
*Shingles
* Lyme disease
* Loss of taste
* Decreased saliva
* Bell’s Palsy.
Cranial Nerves
•
The Vestibulocochlear Nerves (VIII)
– Primary function:
• Special sensory
– Vestibular branch
» Balance and equilibrium
» Originates at receptors of vestibule (balance)
» Connects to vestibular nuclei of pons and medulla
oblongata
Cranial Nerves
•
The Vestibulocochlear Nerves (VIII)
– Primary function:
• Special sensory
– Cochlear branch
» Hearing
» Originates at sensors of cochlea (hearing)
» Connects with cochlear nuclei of pons and medulla
oblongata
Cranial Nerves
• The Vestibulocochlear Nerves (VIII)
– Origin:
• Receptors of inner ear
– Pathway:
• Internal acoustic meatus of temporal bones
Cranial Nerve VIII - Vestibulocochlear
Assessment
**Tuning Fork
Damages
Vertigo
 Rotating
Ataxia
 Lack of coordination
Tinnitus
 Ringing of ears
Cranial Nerves
• The Glossopharyngeal Nerves (IX)
– Primary function:
• Mixed to head and neck
• Origins:
– Motor
*From motor nuclei of
medulla oblongata
– Sensory
» Posterior 1/3 of tongue
» Part of pharynx and
palate
» Carotid arteries
Cranial Nerves
– Superior and inferior ganglion
• Sensory neurons of tongue and pharynx
FIGURE 14-25
Cranial Nerves
• The Glossopharyngeal Nerves (IX)
– Pathway:
• Jugular foramina
– Between occipital and temporal bones
Cranial Nerves
• The Glossopharyngeal Nerves (IX)
– Destination:
• Sensory
– Sensory nuclei of medulla oblongata
• Somatic motor
– Nerves involved in swallowing
Cranial Nerves
• The Glossopharyngeal Nerves (IX)
– Destination:
• Visceral motor
• Parasympathetic Function
– Otic Ganglion
» Parotid salivary
gland
Cranial Nerve - IX Glossophary-ngeal
• Assessment
– Test for taste on posterior 2/3
– Test position of uvula
– Test swallowing and gag reflex
• Damages
– Difficulty in
• Swallowing
• Digestion
• Loss of taste
• Loss of sensation in throat
• Reduced saliva production
Cranial Nerves
• The Vagus Nerves (X)
– “The Vagabond”
• The only cranial
nerve that extends
beyond the head and
neck
– Primary function:
• Mixed
• 90% of
parasympathetic
function
• Thorax and abdomen
Cranial Nerves
• The Vagus Nerves (X)
– Origins:
• Sensory
– Part of pharynx
– Auricle and external
acoustic meatus
– Diaphragm
– Visceral organs of
thoracic and
abdominopelvic
cavities
• Motor
– Motor nuclei in
medulla oblongata
Cranial Nerves
• The Vagus Nerves (X)
– Pathway:
• Jugular foramina
• Between occipital and temporal
bones
Cranial Nerves
– Sensory Neurons
located in
• Superior Ganglion
– Jugular ganglion
• Inferior Ganglion
– Nodose ganglion
Cranial Nerves
• The Vagus Nerves (X)
– Destination:
• Sensory
– Sensory nuclei and
autonomic centers of
medulla oblongata
• Visceral motor
– Parasympathetic
– Muscles of the palate and
pharynx
– Muscles of the digestive,
respiratory, and
cardiovascular systems in
thoracic and abdominal
cavities
Cranial Nerve X - Vagus
• Assessment
•
**Same as IX
• Damages
– Loss of sensations to organs
– Interfere with swallowing, digestion and
vocal cords
– Increase blood pressure
Cranial Nerves
• The Accessory Nerves (XI)
– Primary function:
• Motor to muscles of neck and upper back
– Origin:
• Motor nuclei of spinal cord and medulla oblongata
Cranial Nerves
•
Accessory Nerve Structures
– Spinal root
• Motor fibers that originate in anterior gray horns of first five
cervical segments of spinal cord
– Cranial root
• Motor fibers that originate in medulla oblongata
Cranial Nerves
• The Accessory Nerves (XI)
– Pathway:
• Jugular foramina between occipital and
temporal bones
Cranial Nerves
• The Accessory Nerves (XI)
– Destination:
• Internal branch
– Voluntary muscles of palate, pharynx,
and larynx
Figure 14-27
Cranial Nerves
• The Accessory Nerves (XI)
– Destination:
• External branch
– Sternocleidomastoid and trapezius
muscles
Cranial Nerve XI - Accessory
• Assessment
– Have patient rotate head
– Have patient cough
• Damages
– Ipsilateral paralysis of
sternocleidimastoid and trapezius
• So you can’t raise your
shoulders or turn your head
– Difficulty in swallowing
Cranial Nerves
• The Hypoglossal Nerves (XII)
– Primary function:
• Motor (tongue movements)
– Origin:
• Motor nuclei of medulla oblongata
Cranial Nerves
• The Hypoglossal Nerves (XII)
– Pathway:
• Hypoglossal canals of occipital bone
– Destination:
• Muscles of tongue
Cranial Nerve XII - Hypoglossal
• Assessment
• **Have patient protrude and retract
•
tongue
• Damages
– Atrophy of ipsilateral tongue
– Difficulty
• Swallowing
• Chewing
• Speaking
Cranial Reflexes
• Cranial Reflexes
– Monosynaptic and polysynaptic reflex
arcs
– Involve sensory and motor fibers of
cranial nerves
– Clinically useful to check cranial nerve
for brain damage
CEREBRUM
- I - Olfactory –smell
l
- II - Optic - vision
• BRAINSTEM
– MIDBRAIN
– III - Oculomoter - movement of eye
– IV - Trochlear – movement of eye
– PONS
–
–
–
–
V - Trigeminal – chewing, touch, pain & temperature receptors
VI - Abducens – movement of eyeball
VII - Facial – facial expressions, tears, saliva & taste
VIII - Vestibulocochlear (vestibular branch only). - equilibrium
– Medulla Oblongata
– VIII – Vestibulocohlear – hearing & equilibrium
– IX - Glossopharyngeal – swallowing, taste, saliva production, blood
pressure and monitor breathing
– X - Vagus – swallowing, coughing, voice, blood pressure, monitor
breathing, control digestive secretions & organs of
heart, stomachand G, I tract
– XI - Accessory – swallowing, movement of head and shoulders
– XII - Hypoglossal – swallowing, chewing & speaking