Transcript Cranial Nerves of the Face

Cranial Nerves of the Face
Trigeminal and Facial Nerves
Cranial Nerves of the Face

Movement of the Face
– Facial Expression - Facial Nerve
– Mastication - Trigeminal Nerve

Sensations of the Face
– Trigeminal
– Other
Movement of the Face - Facial
Expression

“Special Visceral” Muscles
– Branchiomeric Muscles

Upper and Lower Face Muscles of
Facial Expression
– ALL innervated by the ipsilateral Facial
Nerve
The Facial Nerve Exits the
Brainstem
A. Ipsilaterally
 B. Contralaterally
 C. Bilaterally
 D. Trilaterally

The Crazy Seventh Nerve
Getting out of the skull

Two Foramen
– Internal Auditory Meatus
» The Whole Nerve
» And a Friend
– Stylomastoid Foramen
» The Motor Root

The Motor Root
– Innervates both Upper and
Lower Muscles, ipsilaterally
Upper and Lower Face Muscles
Facial Nucleus
has upper and
lower face regions
 All projections are
ipsilateral

Dysfunction of the Facial Nerve

Damage to the Motor Root
– Upper and Lower Face are Paralyzed
– Bell’s Palsy

Central Damage (Nerve or Nucleus)
– Ipsilateral Upper and Lower Facial
Paralysis
– And … Tract Damage (ALF, Spinotrigeminal, etc.)

Upper Motor Neuron Damage
Question A: Explain why the
contralateral lower face is
paralyzed but the upper face is
fine when the corticobulbar fibers
are damaged.
UMN Damage to Cranial Nerve 7


Corona
Motor Radiata
Upper Face LMNs are bilaterally innervated
by corticobulbar fibers
Lower Face LMNs are contralaterally
innervated by corticobulbar fibers
Ctx
Internal
Capsule
Motor
Ctx
7u 7l
Cerebral
Peduncle
7u 7l
The Other
Cranial Nerve of the Face
The Trigeminal Nerve
 A Sensory Nerve
 But a Motor Nerve Too!

Describe the origin and extent of
the motor part of the trigeminal
nerve.
Muscles of Mastication

Motor Nucleus of the Trigeminal Nerve
– Innervates “Special”
Visceral Muscles
– Closes the mouth

LMN Lesion
– Ipsilateral Flaccid Paralysis

UMN Lesion
– Bilateral Innervation
– No Loss
Describe how the
sensation produced
by an ant stinging
your forehead
reaches the cortex.
Is there a lateral
and medial route to
the cortex?
Sensation of the Face

Modalities
– Fine Touch and Proprioception
– Pain and Temperature

Examples
–
–
–
–
–
–
Bug crawling/biting face
Jaw open/closed and Eye position
Sand in eye
Bug biting tongue
Headache
Ear ache ?
Trigeminal Nerve Roots

Opthalmic - (V1)
– Superior Orbital Fissure

Maxillary - (V2)
– Rotundum

Mandibular - (V3)
– Ovale
Trigeminal “Dermatomes”
V1
V2
V3
Trigeminal Ganglia and Nuclei

The Semilunar Ganglia
– Gasserian Ganglia
– Near the Turkish Saddle

Nuclei of the Trigeminal Nerve
– Descending (Spinal) Nucleus and Tract
» Pain Fibers
– Chief Sensory Nucleus
» Touch and Proprioception Fibers
Primary Afferent Fibers
Gasserian
Ganglia
Chief Sensory 5
Nucleus
Pain
and
Temperature
Spinal 5
Nucleus
Ascending Projections
Trigeminothalamic Tract
 Lateral Pain Pathway

– Ventral Posterior Medial
Nucleus Internal Capsule
– Postcentral Gyrus
» Lateral

Medial Pain Pathway
– Midline and Intralaminar
Nuclei
– Cingulate Cortex
Cingulate
Cortex
Somatosensory
Cortex
Internal
Capsule
VPM
Midline
Midline
Intralaminar
Gasserian
Ganglia
Chief Sensory 5
Nucleus
Trigeminothalamic
Tract
Pain
and
Temperature
Spinal 5
Nucleus
Describe how the sensation of an
ant crawling on your forehead
reaches the cerebral cortex.
Somatosensory
Cortex
Internal Capsule
Midline
VPM
Trigeminothalamic Tract
Fine Touch
Proprioception
Chief Sensory 5
Nucleus
Spinal 5
Nucleus
Gasserian
Ganglia
The Homunculus
The Clinical Questions
UMN versus LMN face Lesions
 Sensory Loss above and below the
Trigeminal Nerve Exit
