cranial nerves

Question 1

internal cranial base: components

Answer 1

cavernous sinus on either side of sella turcica, contains internal carotid

Question 2

cavernous sinus: contents

Answer 2

CN III, IV, V 1, VI, internal carotid

Question 3

cribriform foramina contents

Answer 3

olfactory nerve (CN I)

Question 4

optic canal contents

Answer 4

optic nerve (CN II)

Question 5

superior orbital fissure contents

Answer 5

oculomotor, trochlear, ophthalmic, abducens (CN III, IV, V1, VI)

Question 6

jugular foramen contents

Answer 6

glossopharyngeal, vagus, spinal accessory nerves (IX, X, XI)

Question 6

foramen ovale contents

Answer 6

mandibular nerve (CN V 3)

Question 7

foramen rotundum contents

Answer 7

maxillary nerve (CN V2)

Question 8

internal acoustic meatus contents

Answer 8

facial, vestibulocochlear nerves (CN VII, VIII)

Question 9

hypoglossal canal contents

Answer 9

hypoglossal nerve (CN XII)

Question 10

foramen spinosum contents

Answer 10

middle meningeal artery, vein

Question 11

olfactory nerves: path

Answer 11

• cell bodies in olfactory nasal mucosa, bipolar neurons form olfactory nerves
• fibers pass through cribriform foramina, synapse w/ mitral cells in olfactory bulb
• axons form olfactory tract

Question 12

optic nerve: path

Answer 12

• passes posterolaterally in orbit, exits optic canal, enters middle cranial fossa, forms optic chiasm

Question 13

optic nerve: fibers

Answer 13

• fibers from median half cross in chiasm, join lateral uncrossed fibers
• crossing required for 3D vision

Question 14

oculomotor nerve: supplies

Answer 14

motor nerve to ocular, extra-ocular muscles

Question 15

oculomotor nerve: path

Answer 15

• emerges from midbrain, pierces dura, runs through cavernous sinus
• leaves cranial cavity, enters orbit through superior orbital fissure and divides

Question 16

oculomotor: divisions

Answer 16

• superior: to superior rectus, levator palpebrae superioris
• inferior: to inferior and medial rectus, inferior oblique, visceral efferent to ciliary ganglion

Question 17

ciliary ganglion

Answer 17

• inferior branch of oculomotor sends visceral efferent signals to ciliary ganglion
• postsynaptic fibers innervate ciliary muscle, sphincter pupillae

Question 18

trochlear nerve: path

Answer 18

around brainstem, anteriorly to lateral wall of cavernous sinus, goes through superior orbital fissure to supply superior oblique (motor)

Question 19

abducens nerve: path

Answer 19

from brainstem between pons, medulla, through superior orbital fissure to supply lateral rectus (motor)

Question 20

trigeminal nerve: ophthalmic branch

Answer 20

goes through superior orbital fissure to supply forehead –> dorsum of nose
- somatic sensory only

Question 21

trigeminal nerve: maxillary branch

Answer 21

passes through foramen rotundum to supply lateral nose, cheek, upper lip
- somatic sensory only

Question 22

trigeminal nerve: mandibular branch

Answer 22

goes through foramen ovale
- sensory to mucosa of tongue, floor of mouth, parotid, temporal region of face
- motor to mastication muscles

Question 23

facial nerve: terminal branches

Answer 23

temporal, zygomatic, buccal, marginal mandibular, cervical

Question 24

facial nerve: path

Answer 24

from junction of pons, medulla, traverses internal acoustic meatus --> anteriorly in temporal bone, turns posteriorly along medial tympanic cavity --> exits stylomastoid foramen

Question 25

facial nerve: types of innervation

Answer 25

- somatic motor: facial expression muscles - visceral motor: pterygopalatine ganglion - somatic sensory: small area of auricle - special sensory: anterior 2/3 of tongue

Question 26

lacrimal gland nervous supply

Answer 26

- greater petrosal (presynaptic parasympathetic) joins deep petrosal (postsynaptic sympathetic) to form pterygoid canal nerve

Question 27

vestibulocochlear nerve: path

Answer 27

from junction of pons, medulla --> internal acoustic meatus

Question 28

glossopharyngeal nerve: path

Answer 28

lateral medulla to jugular foramen

Question 29

glossopharyngeal nerve: types of innervation

Answer 29

- sensory to posterior 1/3 of tongue - parotid gland (visceral), stylopharyngeus (somatic)

Question 30

glossopharyngeal nerve: general sensory branches

Answer 30

pharyngeal, tonsil, lingual

Question 31

glossopharyngeal nerve: afferent branch

Answer 31

gag reflex

Question 32

vagus nerve: path

Answer 32

leaves through jugular foramen, goes through carotid sheath

Question 33

vagus nerve: somatic motor

Answer 33

from nucleus ambiguous: pharyngeal muscles, soft palate, laryngeal muscles

Question 34

vagus nerve: visceral motor

Answer 34

from dorsal nucleus, supply thoracic and abdominal viscera

Question 35

vagus nerve: somatic sensory

Answer 35

posterior ear, external acoustic meatus

Question 36

vagus nerve: special sensory

Answer 36

taste from root of tongue, epiglottis

Question 37

vagus nerve: visceral sensory

Answer 37

mucosa of inferior pharynx at esophageal junction

Question 38

spinal accessory nerve: path

Answer 38

passes through jugular foramen, crosses lateral cervical region, goes deep to superior border of trapezius to supply somatic motor to trapezius and SCM

Question 39

hypoglossal nerve: path

Answer 39

arises from medulla, exits via hypoglossal canal to supply somatic motor to tongue muscles

Question 40

olfactory nerve lesion

Answer 40

anosmia: loss of smell - olfactory bulbs tearing from nerves, fractured cribriform plate - CSF rhinorrhea, cranial base fracture

Question 41

optic nerve lesion

Answer 41

susceptible to demyelinating diseases

Question 42

oculomotor nerve lesion

Answer 42

ptosis, abducted pupil directed inferiorly, no light reflex or accommodation of lens - guillain-barre syndrome

Question 43

trochlear nerve lesion

Answer 43

diplopia when looking down

Question 44

trigeminal nerve lesion

Answer 44

- deviation of mandible towards side of lesion - loss of sensation in face, loss of cornea reflex - trigeminal neuralgia: episodic pain in maxillary, mandibular regions

Question 45

abducens nerve lesions

Answer 45

- can stretch w/ increased intracranial pressure (tumor) - lateral rectus paralysis: eye doesn't fully abduct, medial rectus is unopposed

Question 46

facial nerve lesion

Answer 46

- loss of motor to anterior 2/3 of tongue, gland function - bell's palsy

Question 47

vestibulocochlear nerve lesion

Answer 47

- tinnitus, vertigo, hearing loss - acoustic neuroma

Question 48

glossopharyngeal nerve lesion

Answer 48

isolated: absence of taste on posterior 1/3 of tongue, swallowing changes, absent gag reflex

Question 49

vagus nerve lesion

Answer 49

uvula moves towards normal iside

Question 50

pharyngeal branch of vagus lesion

Answer 50

dysphagia

Question 51

superior laryngeal nerve (branch of vagus) lesion

Answer 51

paralyzed cricothyroid

Question 52

recurrent laryngeal nerve (branch of vagus) lesion

Answer 52

vocal cord paralysis, can occur during neck surgery - both recurrent laryngeal nerves: aphonia, inspiratory stridor

Question 53

spinal accessory nerve lesion

Answer 53

trapezius atrophy, weakness in shoulder elevation, neck/chin rotation

Question 54

hypoglossal nerve lesion

Answer 54

ipsilateral tongue paralysis: dysarthria, tongue points to paralyzed side