Cranial nerves

Question 1

How many muscles of facial expression are there

Answer 1

43

Question 2

Where do the musles of facial experssion originate

Answer 2

Second pharyngeal arch

Question 3

What innervates the muscles of facial expression

Answer 3

Facial nerve from its origin at the brainstem

Question 4

What does the branchial motor of the facial nerve supply

Answer 4

Motor to muscles of facial expression, scalp, stapedius (N.B. hyperacusis)

Question 5

What does the visceral motor of the facial nerve produce

Answer 5

P/S to submandibular and sublingual

Salivary glands, lacrimal gland and glands of nose and palate

Question 6

What CN innervates the taste fibres on the front 2/3 of the tongue

Answer 6

Facial nerve

Question 7

What are internal acoustic neuromas (vestibular schwannoma)

Answer 7

slow growing benign tumours which slowly develop over years

Question 8

What are symptoms/side effects of internal acoustic neuromas

Answer 8

It can cause loss of hearing and altered balance, tinnitus (ringing in the ears), dizziness or vertigo. Larger ones can cause headaches, double vision, or if it presses on the nearby facial nerve, numbness or weakness on 1 side of the face

Question 9

What special sensory innervation does the vestibulocochlear nerve provide

Answer 9

Vestibular sensation (semicircular ducts)

Hearing from spiral organ

Question 10

What is the only muscle in the pharynx innervated by CN IX

Answer 10

Stylopharyngeus

Question 11

What is the purpose of the Stylopharyngeus muscle

Answer 11

This muscle raises the larynx and pharynx and dilates the pharynx to enable food to pass down, thereby helping swallowing

Question 12

What motor innervation does CNIX provide

Answer 12

Somatic Motor:
Motor to stylopharyngeus

Visceral motor:
P/S to parotid gland

Question 13

Does CNIX provide sensory innervation

Answer 13

Visceral sensory:
Parotid gland, pharynx, middle Ear

Special Sensory:
Post. 1/3 tongue

Somatic Sensory:
External ear

Question 14

What CN can be reffered to as the wandering nerve

Answer 14

Vagus X

Question 15

What motor innervation does CNX provide

Answer 15

Somatic Motor:
Muscles of pharynx
Intrinsic muscles of larynx
Muscles of palate
Muscle in upper 2/3 of
Oesophagus

Visceral motor:
P/S to trachea, bronchi, GIT, heart

Question 16

What does CNX provide sensory innervation to

Answer 16

Visceral Sensory:
Tongue, larynx, respiratory tract,
heart, upper GI to Left colic
Flexure

Special Sensory:
Epiglottis and palate

General Sensory:
Auricle, external auditory meatus

Question 17

What does the trapezius do

Answer 17

Helps to raise shoulders

Question 18

How would you test the strenocleidomastoid and trapezius muscles

Answer 18

Ask patient to raise shoulders, turn and flex head against resistance

Question 19

Which CN provides motor innervation to the sternocleidomastoid and trapezius

Answer 19

Accessory nerve CNXI

Question 20

What supplies the palatoglossus

Answer 20

Vagus nerve

Question 21

What does the hypoglossal nerve innervate

Answer 21

Somatic Motor:
Motor to intrinsic and
extrinsic muscles of tongue
(EXCEPT palatoglossus)

Question 22

How can the hypoglossal nerve supply be tested

Answer 22

Ask patient to stick out tongue and it should be symmetrical

Question 23

What is the purpose of the sphincter pupillae

Answer 23

Constriction of the pupil

Question 24

What does somatic motor mean

Answer 24

Not from the pharyngeal arches

Question 25

What does branchial motor indicate

Answer 25

Originates from pharyngeal arches

Question 26

What does visceral sensory indicate

Answer 26

To the lungs and bronchi etc

Question 27

What are the only nerve fibres able to completely regenerate

Answer 27

Olfactory nerve fibres

Question 28

What does anosmia mean

Answer 28

No smell

Question 29

What special sensory innervation does CNI give

Answer 29

Olfactory epithelium Smell from nasal mucosa of each nasal cavity, nasal septum and superior conchae

Question 30

What can be used sometimes in spinal chord injury patients to enable them to regain some function

Answer 30

Olfactory ensheathing cells

Question 31

What is optic chiasm

Answer 31

The crossing point of fibres of the left and right optic nerves. Some fibres stay on the same side, others cross over, and that happens at the chiasm

Question 32

What CN does multiple sclerosis affect

Answer 32

Results in loss of that myelin and can result in weakness of the limbs, and reduction of sight. There could, in severe cases, be complete loss of vision as the axon of the optic nerve is surrounded by myelin, and loss of that will reduce/lose function

Question 33

What special sensory innervation does CNII provide

Answer 33

Nerve cell bodies in retina Exits orbital canal (optic chiasm) Vision from retina

Question 34

What are the extra-ocular muscles

Answer 34

Muscles that surround the eye and are responsible for movement of the eyeball itself

Question 35

What does the ciliary muscle control within the eye

Answer 35

Controls accommodation, or looking at near and far objects, and focusing on things. It alters the shape of the lens, but not the pupillary size

Question 36

What causes compression of the oculomotor nerve

Answer 36

Can be due to many causes eg aneurysms, diabetes, inflammation, trauma. Due to the unopposed action of the lateral rectus (supplied by the abducens nerve) and the superior oblique (supplied by the trochlear nerve)

Question 37

What innervation does CNIII provide

Answer 37

Somatic motor - midbrain: Superior rectus, medial rectus, inferior oblique, levator palpebrae superioris Visceral motor: P/S to sphincter pupillae and ciliary muscle via the ciliary ganglion N.B. Compression of CNIII due to raised intracranial pressure (ICP)

Question 38

What does the IV CN innervate

Answer 38

Somatic motor: Cell bodies located in midbrain Motor to superior oblique N.B. Rarely paralysed on its own Diplopia results in isolated palsy

Question 39

What does CN Va do

Answer 39

General sensory Sensation from cornea, skin of forehead, scalp, eyelids, nose, mucosa of nasal cavities and paranasal sinuses

Question 40

What is CN Vb called

Answer 40

Maxillary branch of trigeminal nerve

Question 41

Where does CNVb give sensation to

Answer 41

Sensation from face over maxilla, upper lip, maxillary teeth (superior alveolar nerve), maxillary sinuses

Question 42

Where does the third branch ofthe trigeminal nerve supply

Answer 42

General sensory: Side of mandible,mandibular teeth (inferior alveolar nerve), mucosa of mouth and ant. 2/3 tongue

Question 43

What innervates the 4 muscles of mastication

Answer 43

Motor division of trigeminal nerve

Question 44

What would a lesion of CNVI cause

Answer 44

Will result in the patient being unable to move their eye laterally on the affected side, and it typically will be medially rotated

Question 45

What supplies the lateral rectus

Answer 45

LR6 - CNVI abducens

Question 46

What CN supplies the superior oblique

Answer 46

SO4 - CNIV trochlear

Question 47

LR6 SO4

Answer 47

Lateral rectus - CN6 Superior oblique - CN4

Question 48

What does CN VI provide motor innervation to

Answer 48

Somatic motor: Arises from pons Motor to lateral rectus