Cranial Nerves

Question 1

What is the anatomical course of the ocularmotor (CN III) nerve?

Answer 1

Arises from ocular motor nucleus- located in midbrain of brainstem and passes closely posterior communicating artery
Nerve enters the cavernous sinus and exits cranial cavity via superior orbital fissure as superior and inferior branches

Superior branch: innervates superior rectus, levator palpebrae superioris
Inferior branch: innervates inferior rectus, medial rectus, inferior oblique

Question 2

What is the anatomical course of the trochlear nerve (CN IV)?

Answer 2

Arises from trochlear nucleus in midbrain of brainstem
Nerve passes along cavernous sinus before entering orbit of eye via superior orbital fissure
Innervates superior oblique

Question 3

What is the anatomical course of the abducens nerve (CNVI) ?

Answer 3

Arises from abducens nucleus in pons of brainstem
Passes through cavernous sinus before entering orbit of eye via superior orbital fissure
Innervates lateral rectus

Question 4

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

Answer 4

V1- ophthalmic division
V2- maxillary divison
V3- Mandibular division

Question 5

What is the anatomical course of the ophthalmic division of the trigeminal nerve?

Answer 5

Passes through cranium via superior orbital fissure. Supplies sensation to forehead, scalp, frontal and ethmoid sinuses, upper eyelid, cornea and upper nose

Question 6

What is the anatomical course of the maxillary division of the trigeminal nerve?

Answer 6

Passes through cranium via foramen rotundum. Supplies sensation to skin and mucous membranes of cheeks, maxillary sinus, nasal cavity and lateral nose, upper lip, upper teeth, gum and superior palate

Question 7

What is the anatomical course of the mandibular division of the trigeminal nerve?

Answer 7

Passes through cranium via foramen ovale. Has motor and sensory fibres
Supply sensation to skin of lower lip, chin, mucous membranes of floor of oral cavity, anterior 2/3 of tongue, lower teeth and gum
Motor innervation to muscles of mastication

Question 8

What is the function of the facial nerve?

Answer 8

Motor- innervation of muscles of facial expression
Sensory- small area of pinnea of ear
Special sensory- taste to anterior 2/3 of tongue
Parasympathetic- glands of head and neck

Question 9

What is the anatomical course of the facial nerve?

Answer 9

Arises from nucleus in pons with motor and sensory root.
Passes through internal acoustic meatus then through stylomastoid foramen exiting skull
Main trunk goes through parotid gland forming 5 branches for facial expression

Question 10

What are the 5 branches of the facial nerve

Answer 10

Cervical
Mandibular
Buccal
Zygomatic 
Temporal

Question 11

What is the function of the glossopharyngeal nerve (CN IX)?

Answer 11

Motor- innervates stylopharangeus muscle of pharynx
Sensory- innervated posterior 1/3 of tongue
Special sensory- taste sensation to posterior 1/3 tongue
Parasympathetic- ps innervation to parotid gland

Question 12

What is the anatomical course of glossopharyngeal nerve (CN IX)?

Answer 12

CN IX arrises from medulla oblongata of brain and leaves cranium via jugular foramen

Question 13

how to you test CN IX?

Answer 13

Elicit gag reflex

Question 14

What is the function of the vagus nerve (CN X)?

Answer 14

Motor- innervation to most of muscles in pharynx and larynx
Sensory- innervation to skin of external acoustic meatus and some surfaces of laryngopharynx and superior larynx. Also visceral sensory info from trachea, lungs, heart, oesophagus and abdominal organs
Parasympathetic: innervates lungs and most of GI tract as well as helping to control heart rate

Question 15

What is the anatomical course of the vagus nerve?

Answer 15

Arises from medulla oblongata and exits via jugular foramen
Pharyngeal branches innervate muscles of pharynx and soft palate
Superior laryngeal nerve innervated cricothyroid muscle
Recurrent laryngeal nerve- right side only

Question 16

How do you test CN X?

Answer 16

Open mouth and say ‘ahhh’
If normal- uvula should raise symmetrically
Uvula deviates away from side of lesion

Question 17

What is the function of the spinal accessory nerve (CN XI)?

Answer 17

Has only motor function innervating sternocleidomastoid and trapezius muscle

Question 18

What is the anatomical course of the spinal accessory nerve?

Answer 18

Spinal portion of accessory nerve arises from upper spinal cord (C1- C5) ad then enters cranial cavity via foramen magnum then heading to jugular foramen
Cranial portion of accessory nerve arises from medulla oblongata before exiting via jugular foramen. Nerve then passes near internal carotid artery heading to SCM and then trapezius muscle

Question 19

How do you test CN XI?

Answer 19

Ask patient to turn head against hand

Question 20

What is the function of the hypoglossal nerve (CN XII)?

Answer 20

Only has somatic motor function innervating muscles of tongue

Question 21

What is the anatomical course of the hypoglossal nerve?

Answer 21

Located in medulla oblongata and leaves cranium via hypoglossal canal

Question 22

How doe you test CN XII?

Answer 22

Patient stick tongue out

Tongue will deviate towards site of lesion