7: Anatomy - Clinical testing of cranial nerves

Question 1

What is the name and modality of CN I?

Where does it emerge from the skull and where does it connect to the CNS?

Answer 1

Olfactory nerve; Special sensory

Remember the part afterwards is the olfactory tract because CN I synapses at the olfactory bulb

Cribriform plate of the ethmoid bone, goes straight to olfactory areas

Question 2

What is the name and modality of CN II?

Where does it emerge from the skull and where does it connect to the CNS?

Answer 2

Optic nerve; Special sensory

Optic canal

Diencephalon

Question 3

What is the name and modality of CN III?

Where does it emerge from the skull and where does it connect to the CNS?

Answer 3

Oculomotor nerve; Motor

Superior orbital fissure

Midbrain

Question 4

What is the name and modality of CN IV?

Where does it emerge from the skull and where does it connect to the CNS?

Answer 4

Trochlear nerve; Motor

Superior orbital fissure

POSTERIOR aspect of the midbrain

Question 5

What is the name and modality of CN V?

Where does it emerge from the skull and where does it connect to the CNS?

Answer 5

Trigeminal nerve; Both sensory and motor

Depends on branch - V1 = superior orbital fissure, V2 = foramen rotundum, V3 = foramen ovale (“standing room only”)

Only CN to connect to CNS at the PONS

Question 6

What is the name and modality of CN VI?

Where does it emerge from the skull and where does it connect to the CNS?

Answer 6

Abducens nerve; Motor

Superior orbital fissure

Ponto-medullary junction

Question 7

What is the name and modality of CN VII?

Where does it emerge from the skull and where does it connect to the CNS?

Answer 7

Facial nerve; Both

Stylomastoid foramen / Internal acoustic meatus

Ponto-medullary junction

Question 8

What is the name and modality of CN VIII?

Where does it emerge from the skull and where does it connect to the CNS?

Answer 8

Vestibulocochlear nerve; Sensory (special)

Internal acoustic meatus

Ponto-medullary junction

Question 9

What is the name and modality of CN IX?

Where does it emerge from the skull and where does it connect to the CNS?

Answer 9

Glossopharyngeal nerve

Jugular foramen

Medulla

Question 10

What is the name and modality of CN X?

Where does it emerge from the skull and where does it connect to the CNS?

Answer 10

Vagus nerve; Both

Jugular foramen

Medulla

Question 11

What is the name and modality of CN XI?

Where does it emerge from the skull and where does it connect to the CNS?

Answer 11

Spinal accessory nerve; Motor

Actually ascends through foramen magnum THEN down through jugular foramen

Cervical spinal cord

Question 12

What is the name and modality of CN XII?

Where does it emerge from the skull and where does it connect to the CNS?

Answer 12

Hypoglossal nerve; Motor

Hypoglossal canal

Medulla

Question 13

Some people say CN II isn’t a real cranial nerve - why?

Answer 13

It has its own meninges, so arguably it’s an extension of the CNS

Remember increases in intracranial pressure cause compression of CN II – papilloedema

Question 14

Which cranial nerve(s)

a) emerge from the pons

b) emerge from the ponto-medullary junction

c) emerge from the opposite side of the brainstem to the others?

Answer 14

a) CN V

b) CN VI, VII and VIII

c) CN IV

Question 15

Where is CN I actually found?

What is everything called proximal to the olfactory bulb?

Answer 15

Olfactory mucosa of nasal cavity

Olfactory tract

Question 16

Through which hole does CN II reach the brain from the orbit?

Answer 16

Optic canal

Question 17

What sense are you testing when you test CN II?

Answer 17

Vision

Question 18

How can CN II be tested?

Answer 18

Visual acuity (Snellen chart)

Colour (Ishihara plates)

Visual fields

Visual reflexes

Direct fundoscopy

Question 19

Which specific modalities are found in CN III?

Answer 19

Somatic motor for eye movements

Parasympathetics for pupillary constriction

Question 20

Which blood-filled space in the brain carries the internal carotid arteries, CN III, IV, V and VI?

Answer 20

Cavernous sinus

Question 21

Which ocular muscles are supplied by CN III?

Answer 21

Medial rectus

Superior rectus

Inferior rectus

Inferior oblique

(Also - LPS, dilator and sphincter pupillae, ciliary muscles)

LR6 SO4 AO3

Question 22

Which cranial nerves supply

a) lateral rectus
b) levator palpebrae superioris
c) superior oblique?

Answer 22

a) CN VI

b) CN III

c) CN IV

Question 23

Which cranial nerves connect to the CNS via the

a) pons
b) ponto-medullary junction
c) cervical spinal cord
d) midbrain
e) medulla?

Answer 23

a) CN V

b) CN VI, VII and VIII

c) CN IX

d) CN III, IV (posteriorly)

e) CN IX, X and XII

Question 24

When the eye is adducted only, which muscle are you testing?

Answer 24

Medial rectus

Question 25

When the eye is **adducted** AND a) **elevated** b) **depressed**? Which muscles are you testing?

Answer 25

**a) Inferior oblique** **b) Superior oblique**

Question 26

When the eye is **abducted only**, which muscle are you testing?

Answer 26

**Lateral rectus**

Question 27

When the eye is **abducted** AND a) **elevated** b) **depressed** which muscle are you testing?

Answer 27

**a) Superior rectus** **b) Inferior rectus**

Question 28

Which special senses does **CN VIII** control?

Answer 28

**Hearing** (Cochlear nerve) **Balance** (Vestibular nerve)

Question 29

Where do **CN VI, VII and VIII** connect to the CNS?

Answer 29

**Ponto-medullary junction**

Question 30

How is **CN VIII** tested?

Answer 30

**Rinne-Weber tests**

Question 31

How do you perform **Weber's test**? What are the possible findings?

Answer 31

**Ask patient which ear is affected** **Use a 512Hz tuning fork (smallest), strike and press to patient's forehead** LOUDEST ON BOTH SIDES = NORMAL LOUDEST ON AFFECTED SIDE = CONDUCTIVE HEARING LOSS LOUDEST ON UNAFFECTED SIDE = SN HEARING LOSS

Question 32

How do you perform **Rinne's test**? What are the possible findings?

Answer 32

**Ask patient which ear is affected** **Strike 512Hz (smallest) tuning fork and press to MASTOID PROCESS for bone conduction** **Then move in front of ear for air conduction** **Ask patient which was louder** AIR CONDUCTION \> BONE CONDUCTION = NORMAL BONE CONDUCTION \> AIR CONDUCTION = CONDUCTIVE HEARING LOSS

Question 33

**CN XI** has a unique connection to the CNS - where is it?

Answer 33

**Cervical spinal cord**

Question 34

What is the function of **CN XI?**

Answer 34

**Somatic motor** to **trapezius** and **sternocleidomastoid**

Question 35

**CN XI** connects to the cervical spinal cord. How does it a) enter b) exit the cranium?

Answer 35

**a) Foramen magnum** **b) Jugular foramen**

Question 36

Which point in the neck is a point where much of the **cervical plexus (C1-4)** overlaps?

Answer 36

**Erb's point** **At the midpoint of the posterior border of sternocleidomastoid**

Question 37

Keeping in mind that it supplies **trapezius** and **sternocleidomastoid**, how do you test **CN XI?**

Answer 37

**Shrug shoulders** **Laterally flex neck**

Question 38

Where does **CN XII** connect to the CNS?

Answer 38

**Medulla**

Question 39

**CN XII** descends through the neck to the **carotid sheathe,** then turns anteriorly at the level of which **bone**? What **muscles** does CN XII supply?

Answer 39

**Hyoid bone** **Intrinsic tongue muscles** (except palatoglossus, which is CN X)

Question 40

Which **muscles** does **CN XII** supply? How do you test **CN XII**?

Answer 40

**Intrinsic tongue muscles** (exception: palatoglossus CN X) ## Footnote **Ask patient to stick their tongue out**

Question 41

If a patient with **unilateral** **CN XII dysfunction** sticks their tongue out, which side will their tongue droop to?

Answer 41

**Towards the affected side** REMEMBER: "tongue tells tales"

Question 42

What are the **three divisions** of the **trigeminal nerve** (CN V)?

Answer 42

**V1** - ophthalmic division **V2** - maxillary division **V3** - mandibular division

Question 43

Which **nerve modalities** are carried in a) CN V1 b) V2 c) V3?

Answer 43

**a) Sensory** **b) Sensory** **c) Sensory and Motor**

Question 44

Which part of the **brainstem** does **CN V** connect to?

Answer 44

**Pons** only one which does this, important fact

Question 45

From which **cranial fossa** does each branch of **CN V** exit?

Answer 45

**All middle cranial fossa**

Question 46

What is the mnemonic for remembering the **cranial foramina** that **CN V** exits from?

Answer 46

**S**tanding **r**oom **o**nly CN V1 = superior orbital fissure CN V2 = foramen rotundum CN V3 = foramen ovale

Question 47

Which aspects of the **nose** are supplied by **CN V1**?

Answer 47

**Bridge** **Tip**

Question 48

Which infection follows nerves and can damage the cornea if CN V1 is affected?

Answer 48

**Herpes zoster** or 'Ophthalmic zoster'

Question 49

Which aspect of the nose is supplied by CN V2?

Answer 49

**Alae** (sides)

Question 50

Which nerves supply sensory fibres to a) the **angle of the mandible** b) the **TMJ** c) most of the **skin of the mandible**?

Answer 50

**a) Great auricular nerve** (C2 and 3) **b) CN V3** **c) CN V3**

Question 51

What the **named nerves** and **levels** of the **cervical plexus**?

Answer 51

**Lesser occipital (C2)** **Greater auricular (C2-3)** **Transverse cervical (C2-3)** **Supraclavicular (C3-4)**

Question 52

Which aspects of the **nasal cavity** are given sensory fibres by branches of the **trigeminal nerve?**

Answer 52

**CN V1** - upper, anterior aspect **CN V2** - lower, posterior aspect

Question 53

Which **paranasal sinuses** are supplied with sensory fibres by **CN V1**?

Answer 53

**Frontal sinus** **Ethmoidal air cells** **Sphenoid sinuses**

Question 54

Which **paranasal sinus** is given sensory fibres by **CN V2?**

Answer 54

**Maxillary sinus** Or 'maxillary antrum'

Question 55

**CN V3** gives off both **sensory AND motor fibres**. Which **facial** **muscles** are supplied by CN V3?

Answer 55

**Muscles of mastication** (Masseter, temporalis, medial and lateral pterygoids)

Question 56

Which muscles of mastication a) open b) close the jaw?

Answer 56

**a) Lateral pterygoid OPENS the jaw** **b) Masseter, temporalis and medial pterygoid CLOSE the jaw**

Question 57

In addition to the **muscles of mastication**, **CN V3** supplies two other muscles in the head and neck. What are they called?

Answer 57

**TENSOR VELI PALATINI** **TENSOR TYMPANI** **Trigeminal** nerve does the **tensors**

Question 58

How do you test the **sensory fibres** of **CN V?**

Answer 58

**Touch skin in divisions of trigeminal nerve**

Question 59

How do you test the **motor fibres** of **CN V?**

Answer 59

**Ask patient to CLENCH THEIR TEETH** - tests masseter and temporalis **Ask patient to OPEN JAW AGAINST RESISTANCE** - tests lateral pterygoid

Question 60

Which **nerve modalities** are carried by **CN VII?**

Answer 60

**Somatic motor** - to muscles of facial expression AND stapedius **Parasympathetic** - to submandibular and sublingual glands **Special sensory** - to taste buds of anterior 2/3rds of tongue

Question 61

**Does CN VII supply the parotid gland?**

Answer 61

**No, but its fibres pass through it**

Question 62

Which **bone** does **CN VII** run through?

Answer 62

**Temporal bone** IN via the internal acoustic meatus, OUT via the stylomastoid foramen

Question 63

Which specific part of the **temporal bone** does **CN VII** run through?

Answer 63

**Petrous part** via the **facial canal**

Question 64

Which **passage** connects the **internal acoustic meatus** to the **stylomastoid foramen**?

Answer 64

**Facial canal**

Question 65

Through which foramen does most fibres of CN VII exit the temporal bone?

Answer 65

**Stylomastoid foramen**

Question 66

What happens to the **somatic motor** fibres of **CN VII** which exit the stylomastoid foramen?

Answer 66

**Run down into parotid gland** **Then split into 5 named nerves to supply the muscles of facial expression**

Question 67

Which **branch of CN VII** supplies **special sensory fibres to the anterior 2/3rds of tongue** and **parasympathetic fibres to the submandibular and sublingual glands**?

Answer 67

**Chorda tympani**

Question 68

Which **cranial nerve** does the **chorda tympani** hitch a ride with to supply the tongue and salivary glands?

Answer 68

**CN V3** Mandibular division of trigeminal nerve

Question 69

What are some of the **muscles of facial expression**?

Answer 69

**Frontalis** **Orbicularis oculi** **Orbicularis oris**

Question 70

How can you test the **motor fibres** of **CN VII?**

Answer 70

**Ask patient to make facial expressions**

Question 71

Which skeletal muscle, the smallest found in the body, is supplied by **CN VII**?

Answer 71

**Stapedius**

Question 72

What is **supplied with special sensory** **fibres** by **CN IX?**

Answer 72

**Posterior 1/3rd of tongue**

Question 73

What is supplied with **somatic sensory fibres** by **CN IX?**

Answer 73

**Pharynx** **Tonsils** **Posterior 1/3rd of tongue** **Eustachian tube** **Middle ear**

Question 74

Which **muscle** is the only one supplied with **somatic motor** fibres by **CN IX?**

Answer 74

**Stylopharyngeus**

Question 75

Which receptors, found in the **carotid sinus**, are supplied with **visceral afferent** fibres by **CN IX?**

Answer 75

**Chemoreceptors** **Baroreceptors**

Question 76

Which **gland** is given **parasympathetic fibres** by **CN IX?**

Answer 76

**Parotid gland**

Question 77

Which **cranial nerves** supply the a) **submandibular** b) **parotid** c) **sublingual glands?**

Answer 77

**a) CN VII** **b) CN IX** **c) CN VII**

Question 78

Which cranial nerves supply a) **stylopharyngeus** b) **palatoglossus** c) **stapedius** d) **tensor veli palatini and tensor tympani** e) **sternocleidomastoid and trapezius?**

Answer 78

**a) CN IX** **b) CN X** **c) CN VII** **d) CN V** **e) CN XI**

Question 79

Which **cranial nerve** is also known as the **wanderer** because it has so many modalities and travels throughout the body?

Answer 79

**CN X**

Question 80

Where does **CN X** extend to?

Answer 80

**Midgut**

Question 81

**In the neck, CN X** runs within the ___ \_\_\_.

Answer 81

**carotid sheathe**

Question 82

What is the course of the a) **left** b) **right recurrent laryngeal nerve**?

Answer 82

a) **Hooks under arch of aorta** b) **Hooks under right subclavian artery**

Question 83

**CN X** passes **(anterior / posterior)** to the lung roots.

Answer 83

**posterior to lung roots**

Question 84

In what arrangement do the **left and right vagus nerves** pass along the oesophagus? At which level does the oesophagus penetrate the **diaphragm**?

Answer 84

**LARP** - left anterior, right posterior **T10** (dermatomal level of the umbilicus)

Question 85

Where in the abdomen do the **vagus nerve's LAST parasympathetic axons** go?

Answer 85

**Splenic flexure**

Question 86

Where in the abdomen do **CN X's parasympathetic nerves synapse**?

Answer 86

**Coeliac ganglion** **Superior mesenteric ganglion** because it extends to the midgut only

Question 87

Which **muscles** are supplied by **CN X?**

Answer 87

**Muscles of palate** (except tensor veli palatini, which is CN V) **Pharyngeal muscles** **Laryngeal muscles** Plus **palatoglossus** (the rest are CN XII)

Question 88

In terms of testing **CN X**, how do you test a) **the muscles of the palate** b) **pharyngeal muscles** c) **laryngeal muscles**?

Answer 88

**a) Say AAAAAH** **b) Swallow** **c) Speak**

Question 89

If a **palatal muscle** e.g **levator veli palatini** isn't working, which structure will **deviate** when the patient says ahhh?

Answer 89

**Uvula**

Question 90

What side does the **uvula** deviate to when a palatal muscle isn't working?

Answer 90

**AWAY from dysfunctional side** (Tongue tells tales i.e it deviates to affected side, uvula does the opposite)