The Cranial Nerves

Question 1

What is cranial nerve 8?

Answer 1

Vestibulocochlear nerve

Question 2

Which number is the abducens nerve?

Answer 2

CN VI

Question 3

What number is the trochlear nerve?

Answer 3

CN IV

Question 4

Name cranial nerve IX

Answer 4

Glossopharyngeal nerve

Question 5

What is CN I?

Answer 5

Olfactory nerve

Question 6

What is cranial nerve XI?

Answer 6

Accessory spinal nerve

Question 7

Name cranial nerve XII?

Answer 7

Hypoglossal nerve

Question 8

Which cranial nerves have autonomic components?

Answer 8

III, VII, IX and X

Question 9

What is the function of CN I and how is this tested?

When might this function be inhibited?

Answer 9

Smell - use smelling salts one nostril at a time

Anosmia - temporary with URTI, permanent in Cribriform plate fracture

Question 10

Describe the course of the olfactory nerve

Answer 10

Nasal mucosa –> Cribriform plate –> olfactory bulb in anterior cranial fossa

Question 11

How would you test the optic nerve?

Answer 11

Visual acuity
Colour vision
Visual fields
Pupillary reflexes
Fundoscopy

Question 12

Describe the course of CN II

Answer 12

Retina –> optic canal –> optic tract –> primary visual cortex in occipital lobe

Question 13

What are the functions of the oculomotor nerve?

Answer 13

• motor to extra ocular muscles except LR and SO - moves eyeball
• motor to LPS - opens eyelid
• parasympathetic constricts pupil via sphincter pupillae

Question 14

Describe the course of the oculomotor nerve

Answer 14

Motor begins in oculomotor nucleus of midbrain, parasympathetic begins in Edinger-Westphal nucleus.
Passes through cavernous sinus and superior orbital fissure.

Question 15

List the 3 major causes for oculomotor palsy?

Answer 15

• increases intracranial pressure
• aneurysm of the posterior cerebral artery
• cavernous sinus infection

Question 16

What are the 3 signs of oculomotor palsy, assuming damage is proximal to the ciliary ganglion?

Answer 16

Down and out pupil
Ptosis
Blown pupil

Question 17

What is the function of CN IV?

Answer 17

Motor to superior oblique muscle so allows eye to move down and in

Question 18

Describe the course of CN IV

Answer 18

Trochlear nucleus in midbrain –> cavernous sinus –> superior orbital fissure

Question 19

What signs would you find on examination if there was CN IV palsy?

Answer 19

Diplopia when looking down and in

Possible head tilt and neck stiffness

Question 20

What single problem could cause palsy of CNs III, IV and VI?

Answer 20

Cavernous sinus infection

Question 21

Give a brief overview of the course of CNV

Answer 21

Begins in pons - 1 sensory root and 1 motor root
In middle cranial fossa, sensory root forms trigeminal ganglion - V1 - superior orbital fissure
V2 - foramen rotundum
V3 - foramen ovale

Question 22

List the functions of the trigeminal nerve

Answer 22

Sensory to the face

Muscles of mastication

Question 23

Which nerve produces the corneal reflex?

Answer 23

V1

Question 24

What is the course of the abducens nerve?

Answer 24

Abducens nucleus in pons –> cavernous sinus –> superior orbital fissure

Question 25

What sign would indicate palsy of the 6th cranial nerve?

Answer 25

Inability to abduct the eye

Question 26

Describe the course of the facial nerve

Answer 26

Arises in the pons Through IAM into facial canal In facial canal, forms geniculate ganglion and gives off greater petrosal nerve, nerve to stapedius and chords tympani Exits facial canal and cranium via style mastoid foramen Runs to anterior to pinna - gives off posterior auricular and motor fibres to digastric and Stylohyoid Continues to parotid - splits into 5 terminal branches

Question 27

List the functions of the facial nerve

Answer 27

Taste Muscles of facial expression Lacrimation Salivation

Question 28

What is the most likely cause of facial nerve palsy?

Answer 28

Middle ear pathology

Question 29

Which foramen does CN VIII pass through?

Answer 29

IAM When you think about this, it makes complete sense seeing as it supplies the ear

Question 30

What are the functions of the Glossopharyngeal nerve?

Answer 30

Sensory to oropharynx, posterior tongue, carotid and parotid Motor to stylopharyngeus Parasympathetic to parotid

Question 31

What is the course of cranial nerves IX and X?

Answer 31

Originate in the medulla oblongata and pass through the jugular foramen

Question 32

What are the functions of the vagus nerve?

Answer 32

Sensory to laryngopharynx and ear Motor to laryngeal and pharyngeal muscles Parasympathetic to heart, lungs and GI tract

Question 33

Which nerves are involved in the gag reflex?

Answer 33

CN IX - Afferent | CN X - efferent

Question 34

Where does the accessory nerve originate?

Answer 34

Spinal - C1 - C5 | Medulla oblongata

Question 35

Which foramen does the hypoglossal nerve pass through?

Answer 35

Hypoglossal canal

Question 36

Compare and contrast deviation of the uvula and tongue?

Answer 36

- uvula - vagus nerve - deviates away from lesion | - tongue - hypoglossal nerve - deviates towards lesion

Question 37

Why is frowning still possible in facial nerve palsy?

Answer 37

Frontalis muscle has bilateral innervation so it still receives innervation from the unaffected side

Question 38

What is Harlequin syndrome?

Answer 38

- damage to autonomic fibres of CN V at level of thoracic cord - results in lack of sweating (anhydrosis) and vasomotor dysfunction (no vasodilation) after exercise on the affected side

Question 39

Which cranial nerves are located in the anterior triangle? Of these, which are also in the carotid triangle? What about the carotid sheath?

Answer 39

Anterior triangle - CNs VI, IX, X, XI and XII Carotid triangle - CN X + XII Carotid sheath - CN X only

Question 40

Which cranial nerve(s) is/are located in the posterior triangle?

Answer 40

CN XI

Question 41

Which cranial nerves pass through the cavernous sinus?

Answer 41

III, IV, V1, V2 and VI

Question 42

State which CNs go through which cranial fossa

Answer 42

Anterior - I and II Middle - III to VII Posterior - VIII to XII

Question 43

Which cranial nerves originate from each of the following: Midbrain Pons Medulla

Answer 43

Midbrain - III and IV Pons - V to VIII Medulla - IX to XII