Peripheral Distribution of Cranial Nerves

Question 1

What supplies the majority of the extraocular muscles?

Answer 1

Oculomotor nerve (CN III)

Question 2

Which nerve innervates the superior oblique muscle?

Answer 2

CN IV (trochlear)

Question 3

Which nerve innervates the lateral rectus muscle?

Answer 3

CN VI (abducens)

Question 4

Which nerve is sensitive to the sclera of the eye?

Answer 4

Ophthalmic division of trigeminal (CN V1)

Question 5

Which nerve innervates the ciliary muscle and sphincter pupillae?

Answer 5

Oculomotor (CN III)

Question 6

What is Horner’s syndrome caused by?

Answer 6

Lack of sympathetic innervation to the eye, usually due to damage of the cervical sympathetic chain

Question 7

Outline the symptoms of trochlear palsy

Answer 7

There is paralysis of the superior oblique –> eye elevation, hardest to diagnose (but is rarest) and the patient may attempt to minimise double vision by tilting their head (tilted to opposite side than affected eye)

Question 8

What is the motor function of the mandibular nerve (CN V3)?

Answer 8

Has postsynaptic parasympathetic fibres to the muscles of mastication

Question 9

What is the sensory function of the mandibular nerve (CN V3)?

Answer 9

To lower dentition (inferior alveolar) and tongue

Question 10

What is the function of the ophthalmic branch (CN V1)?

Answer 10

Sensory to the lacrimal glands, forehead and nasociliary region

Question 11

What is the function of the maxillary branch (CN V2)?

Answer 11

Sensory to the infraorbital foramen, upper dentition (superior alveolar), palate and gums

Question 12

What are the two main divisions of the facial nerve?

Answer 12

Large motor division and smaller intermediate nerve

Question 13

Describe the motor function of the facial nerve (CN VII)

Answer 13

Travels through internal auditory meatus and exits in the stylomastoid foramen to supply the muscles of facial expression

Question 14

Describe the special sensory function of the facial nerve (CN VII)

Answer 14

Taste to anterior 2/3 of tongue by travelling with the chorda tympani

Question 15

Describe the parasympathetic function of the facial nerve (CN VII)

Answer 15

Gives off the branch of the greater petrosal nerve and causes secretions at the lacrimal, submandibular and sublingual glands

Question 16

Name the 5 branches of the somatic portion of the facial nerve (CN VII)

Answer 16

Temporalis, zygomatic, buccal, marginal mandibular and cervical

Question 17

Describe the passage and function of the vestibulocochlear nerve (CN VIII)

Answer 17

Passes through the internal auditory meatus and is involved in hearing (cochlear portion)

Question 18

Describe the function of the glossopharyngeal nerve (CN IX)

Answer 18

Sensory to pharynx and larynx (stimulates gag reflex if touched), supplies taste to posterior 1/3 of tongue, parasympathetic innervation to the parotid gland (via otic ganglion) and provides somatic sensory information to the carotid sinus

Question 19

Describe the sensory function of the vagus nerve (CN X)

Answer 19

Lower pharynx, larynx and aortic body

Question 20

Describe the motor function of the vagus nerve (CN X)

Answer 20

Muscles of palate, pharynx, larynx, oesophagus, and parasympathetic to thoracic and abdominal viscera

Question 21

Describe the function of the spinal accessory nerve (CN XI)

Answer 21

Fibres to underside of SCM muscles and to lateral trapezius

Question 22

What are the symptoms of spinal accessory nerve injury?

Answer 22

Weakened shoulder shrugging

Question 23

Describe the function of the hypoglossal nerve (CN XII)

Answer 23

Motor to the tongue

Question 24

What are the symptoms of hypoglossal nerve injury?

Answer 24

Paralysis of the ipsilateral side of the tongue –> deviation of the tongue towards side of lesion

Question 25

Which nerves ‘hitch a lift’ with the hypoglossal nerve?

Answer 25

C1 and C2 hitch a lift to the infrahyoid muscles

Question 26

Name the 4 cranial nerves with parasympathetic modalities

Answer 26

Oculomotor, facial, glossopharyngeal and vagus

Question 27

What is the parasympathetic function of the oculomotor nerve?

Answer 27

Pupil constriction and accommodation reflex

Question 28

What is the parasympathetic function of the facial nerve?

Answer 28

lacrimal glands, mucosal glands of nose/palate, submandibular and sublingual glands

Question 29

What is the parasympathetic function of the glossopharyngeal nerve?

Answer 29

Parotid gland

Question 30

What is the parasympathetic function of the vagus nerve?

Answer 30

Heart and gut to 2/3 along transverse colon