Session 8 - Trigeminal and facial nerves

Question 1

Why are cranial nerves called cranial nerves?

Answer 1

Because they emerge through foramina or fissures in the cranium and are covered by tubular sheathes derived from the cranial meninges

Question 2

What are the three main branches of the trigeminal nerve?

Answer 2

 Opthalmic (CN V1)
 Maxillary (CN V2)
 Mandibular (CN V3)

Question 3

Where does the trigeminal nerve arise?

Answer 3

The Trigeminal Nerve arises from the Lateral Aspect of the Pons by a large sensory root and small motor root. The crescent shaped Trigeminal Ganglion sits within a Dural recess, the Trigeminal Cave, which sits laterally to the cavernous sinus. P

Question 4

Where does the opthalmic nerve exit the skull?

Answer 4

The superior orbital fissure

Question 5

What is opthalmic nerve sensory for?

Answer 5

• Scalp
• Forehead
• Upper eye lid and conjunctiva
• Cornea
• Anterosuperior nasal cavity
• Frontal and ethmoid sinus
• External nose

Question 6

How is the opthalmic nerve tested?

Answer 6

Corneal reflex

Question 7

What are the three main branches of the opthalmic nerve?

Answer 7

 Frontal
 Nasocillary
 Lacrimal

Question 8

What does the lacrimal gland provide sensory inneervation for?

Answer 8

• Lacrimal Gland
• Conjuctiva
- Carries parasympathetic secretomotor fibers to the lacrimal gland

Question 9

How does the maxillary branch exit the skull?

Answer 9

Foramen rotundum

Question 10

What does the maxillary nerve innervate?

Answer 10

	Inferior Conjunctiva and inferior eye lid
	Nasal Cavity (Posteroinferior)
	Lateral External Nose
	Maxillary Sinus
	Superior palate
	Upper lip

Question 11

What parasympathetic ganglion is the maxillary nerve associated with?

Answer 11

Pterygopalantine

- Innervates lacrimal, nasal and palate glands

Question 12

Where does the mandibular nerve exit the skull?

Answer 12

The foramen ovale

Question 13

What is mandibular nerve sensory for?

Answer 13

o	Mucous membranes
o	Lower Lip
o	Chin
o	External Ear (Front of auricle)
o	Anterior two thirds of tongue (General Sensation, not taste!)

Question 14

What is mandibular nerve motor innervation for?

Answer 14

	Masseter
	Temporalis
	Medial and Lateral Pterygoids
	Mylohyoid
	Digastric
	Tensor Tympani
	Tensor Vele Palatini

Question 15

What parasympathetic ganglia is the mandibular nerve associated with?

Answer 15

Submandibular ganglion
- Submandibular salivary gland 
- Sublingual salivary gland
Otic ganglion
- Parotid salivary gland

Question 16

How does the facial nerve exit the skull?

Answer 16

Through the stylomastoid foramen

Question 17

What does the facial nerve provide motor innervation for?

Answer 17

 Muscles of facial expression
 Digastric (posterior belly)
 Stylohyoid
 Stapedius

Question 18

What does the facial nerve provide sensory innervation for?

Answer 18

	General Sensory
•	Small area of skin close to external acoustic meatus
	Special Sensory (Taste)
•	Corda Tympani from the Lingual Nerve 
•	Taste Anterior 2/3rds of the tongue

Question 19

What does the facial nerve carry parasympathetic nerve fibers to and via what ganglion?

Answer 19

 Pterygopalatine Parasympathetic Ganglion
 Lacrimal Gland
 Submandibular Gland
 Sublingual Gland

Question 20

Outline the course of the facial nerve

Answer 20

Motor cortex -> Pons (facial motor nucleus) -> Internal acoustic meatus (within petrous temporal bone) -> facial canal (temporal bone) -> Stylomastoid foramen -> Branches to face and neck (through parotid gland!)

Question 21

Give three nerves which arise in facial canal

Answer 21

• Greater Petrosal Nerve
• Nerve to the Stapedius
• Chorda Tympani Nerve

Question 22

Give a nerve which arises from stylomastoid foramen

Answer 22

Posterior auricular branch

Question 23

What five branches of the facial nerve divide off after it exits stylomastoid foramen

Answer 23

Ten Zebras Buggered My Cat
Temporal
Zygomatic
Buccal
Marginal Mandibular
Cervical

Question 24

What does the temporal branch of the facial nerve innervate?

Answer 24

 Occipitofrontalis

 Orbicularis Oculi (Superior)

Question 25

What does the zygomatic branch of the facial nerve innervate?

Answer 25

 Orbicularis Oculi (Inferior)

Question 26

What does the buccal branch of the facial nerve innervate?

Answer 26

 Orbicularis Oris
 Buccinator
 Zygomaticus

Question 27

What does the marginal mandibular branch of the facial nerve innervate?

Answer 27

Mentalis

Question 28

What does the cervical branch of the facial nerve innervate?

Answer 28

Platysma

Question 29

How do you examine the facial nerve?

Answer 29

Observation
Ask
Physical examination

Question 30

What do you observe in facial nerve examination?

Answer 30

Loss of facial symmetry

Question 31

What do you ask about in facial nerve examination?

Answer 31

	Change in taste?
•	Chorda Tympani
	Change in hearing?
•	Hyperacusis
•	Nerve to Stapedius
	Dry eye / unable to cry?
	Dry mouth?

Question 32

What do you examine physically in facial nerve exam?

Answer 32

	Occipitofrontalis
•	Raise Eyebrows
•	Keep them raised against resistance
	Orbicularis Oculi
•	Scrunch up eyes
•	Keep them scrunched up against resistance
	Buccinator
•	Puff out cheeks
•	Keep puffed out against resistance
	Levator Labii Superioris
	Depressor Labii Inferioris
•	Show Teeth
•	Keep them shown against resistance

Question 33

Give three non-traumatic causes of facial nerve palsy

Answer 33

o	Inflammation
o	Infection
	Viral (Herpes)
	Parotitis (S. Aureus)
o	Compression
	Parotid Tumour

Question 34

Give four traumatic causes of facial nerve palsy?

Answer 34

o	Fractures
	Temporal Bone
o	Stabbing
o	Gunshots
o	Childbirth

Question 35

Give an iatrogenic cause of facial nerve palsy

Answer 35

Surgery

Question 36

What is the difference between symptom’s of stroke and bell’s palsy?

Answer 36

o Bell’s Palsy
 All muscles of facial expression paralysed
o Stroke
 Frontal Sparing
 Occipitofrontalis and Orbicularis Oculi not paralysed
 Due to their Bilateral Innervation