Cranial Nerves And Autonomic Innervation

Question 1

What is the function of CN II

Answer 1

Optic nerve - sensory

Sight

Question 2

What is the function of CN III

Answer 2

Oculomotor - motor

Innervates extraocular muscles (except LR, SO)
Innervates ciliary muscles and sphincter pupillae

Question 3

What is the function of CN IV

Answer 3

Trochlear nerve - Motor

Innervates Superior Oblique

Question 4

What is the function of CN V

Answer 4

Trigeminal nerve - sensory motor (3 divisions)

Ophthalmic - Sensory - skin, corneal reflex
Maxillary - Sensory - skin, nose, palate, upper teeth
Mandibular - Sensory - skin, lower teeth, cheek, anterior 2/3 tongue. Motor - mastication

Question 5

What is the function of CN VI

Answer 5

Abducens nerve - motor

Innervates Lateral Rectus

Question 6

What is the function of CN VII

Answer 6

Facial nerve - sensory motor

Special Sensory - Taste of anterior 2/3 tongue
General Sensory - External acoustic meatus, auricle
Motor - Muscles of facial expression; parasympathetic secretomotor to submandibular and sublingual salivary glands, lacrimal glands, nasal mucosa, paranasal sinuses, palate

Question 7

What is the function of CN VIII

Answer 7

Vestibulocochlear nerve - sensory

Special Sensory - Balance (vestibular) and hearing (cochlear)

Question 8

What is the function of CN IX

Answer 8

Glossopharyngeal nerve - sensory motor

Special Sensory - taste to posterior 1/3 tongue
General Sensory - pharynx, palate, auditory tube, mastoid, carotid body and sinus
Motor - Stylopharyngeus, parasympathetic secretomotor to parotid salivary gland

Question 9

What is the function of CN X

Answer 9

Vagus nerve - sensory motor

Special Sensory - taste at epiglottis
General Sensory - lower pharynx, larynx, external auditory meatus, back of auricle
Motor - muscles of pharynx (except stylopharyngeus), airways, larynx, heart, GI, palate

Question 10

What is the function of CN XI

Answer 10

Spinal Accessory Nerve - motor

Innervates pharynx, larynx, soft palate, trapezius, sternocleidomastoid

Question 11

What is the function of CN XII

Answer 11

Hypoglossal nerve - motor

Innervation of tongue (except palatoglossus)

Question 12

How can CN I be damaged

Answer 12

Cribiform plate fracture

Causes anosmia. Can be associated with CSF rhinorrhea

Question 13

How can CN II be damaged

Answer 13

Trauma to eye / orbit; optic canal fracture / pressure

Can cause loss of pupillary constriction and visual field defects

Question 14

How can CN III be damaged

Answer 14

Cavernous sinus fracture, aneurysm

Can present with dilated pupil, ptosis, eye turned down and out

Question 15

How can CN IV be damaged

Answer 15

Stretching of nerve, orbit fractures

Causes inability to look down and in

Question 16

How can CN V be damaged

Answer 16

Nerve lesions

Can cause muscle paralysis and sharp facial pain

Question 17

How can CN VI be damaged

Answer 17

Cavernous sinus fractures, orbit fractures

Eye fails to move laterally

Question 18

How can CN VII be damaged

Answer 18

Laceration in parotid region: Bell’s Palsy, facial paralysis, eye open, forehead doesn’t wrinkle

Fracture of temporal bone: Bell’s Palsy, dry cornea, loss of taste in ant. 2/3 tongue

Intracranial haematoma: forehead wrinkles due to frontalis involvement

Question 19

How can CN VIII be damaged

Answer 19

Skull fracture, ear infection, acoustic neuroma

Progressive hearing loss, tinnitus, vertigo

Question 20

How can CN IX be damaged

Answer 20

Deep neck lacerations

Loss of taste to post. 1/3 tongue

Question 21

How can CN X be damaged

Answer 21

Nerve lesions in neck affect recurrent laryngeal branch, causing hoarseness of voice

Thyroidectomy can damage superior laryngeal branch

Question 22

How can CN XI be damaged

Answer 22

Surgery / lacerations in neck, causing paralysis of SCM and superior trapezius, thus shoulder droop

Question 23

How can CN XII be damaged

Answer 23

Neck laceration and basal skull fracture

Tongue deviates towards affected side

Question 24

What is the location of the Sympathetic Trunk

Answer 24

Anterolateral to vertebral column
Lying on prevertebral fascia and muscles
Deep to carotid sheath

Question 25

Where do fibres travel from the Superior Cervical Ganglion

Answer 25

With external and internal carotid arteries to: Pharyngeal plexus Upper 4 cervical nerves Cardiac plexus

Question 26

Where do fibres travel from the Middle Cervical Ganglion

Answer 26

With the inferior thyroid artery to 5th and 6th cervical nerves Cardiac plexus

Question 27

Where do fibres travel from the Inferior Cervical Ganglion

Answer 27

With the vertebral artery to 7th and 8th cervical nerves Cardiac plexus

Question 28

What are the 4 pairs of parasympathetic ganglia in the head

Answer 28

Ciliary ganglion Pterygopalatine ganglion Submandibular ganglion Otic ganglion

Question 29

Which 4 cranial nerves have parasympathetic brainstem nuclei

Answer 29

Oculomotor (Branches to Ciliary ganglion) Facial (Branches to Pterygopalatine / Submandibular ganglia) Glossopharyngeal (Branches to Otic ganglion) Vagus (No associated ganglion)

Question 30

Where is the Ciliary Ganglion found Where does it send fibres

Answer 30

Orbital cavity Parasympathetic: sphincter papillae, ciliary muscles Sympathetic: eyeball

Question 31

Where is the Pterygopalatine Ganglion found Where does it send fibres

Answer 31

Lies in the Pterygopalatine fossa Parasympathetic: lacrimal glands, glands of nose, palate, nasopharynx Sympathetic: nose, palate, nasopharynx

Question 32

Where is the Submandibular Ganglion found Where does it send fibres

Answer 32

Suspended from lingual nerve Parasympathetic: submandibular and sublingual glands, glands in floor of oral cavity Sympathetic: glands in floor of oral cavity

Question 33

Where is the Otic Ganglion found Where does it send fibres

Answer 33

Located in the infratemporal fossa Parasympathetic: parotid gland Sympathetic: parotid gland

Question 34

What is Horner's Syndrome?

Answer 34

Interruption of a cervical sympathetic trunk Causes absence of sympathetically stimulated functions on ipsilateral side

Question 35

What is the presentation of Horner's Syndrome?

Answer 35

Miosis (contracted pupil) Ptosis (due to superior tarsal paralysis) Vasodilation Anhydrosis (absence of sweating)

Question 36

What is the function of CN I

Answer 36

Olfactory nerve - sensory Special sensory fibres for smell