Lecture 6 - Cranial Nerves

Question 1

Where does the neural plate develop?

Answer 1

In the ectoderm

Question 2

Lateral margins of the neural plate grow upward to form what?

Answer 2

The neural folds/neural groove

Question 3

The neural folds meet at the midline, fuse, and form what?

Answer 3

The neural tube

Question 4

What is a notochord?

Answer 4

Defines the axis of the embryo, basis for the axial skeleton and future site of the vertebrae

Question 5

Neural crest cells give rise to what?

Answer 5

The peripheral nervous system

Question 6

From where does the spinal cord develop?

Answer 6

The caudal end of the neural tube

Question 7

The neural tube differentiates into what 3 encephalons?

Answer 7

Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhombencephalon (hindbrain)

Question 8

Based on the embryology of the cranial nerves, where do the nerves fall in the different ‘encephalons’ of the brain?

Answer 8

Tel - i
Die - ii
Mes - iii, iv
Met – v, vi, vii, viii
Mye – ix, x, xi, xii

Question 9

Pharyngeal arch 1 gives rise to which cranial nerve? This serves what function?

Answer 9

CN V - trigeminal
Muscles of mastication

Question 10

Pharyngeal arch 2 gives rise to which cranial nerve? This serves what function?

Answer 10

CN VII - facial
Facial expression

Question 11

CN IX (glossopharyngeal) is derived from which pharyngeal arch?

Answer 11

3

Question 12

Pharyngeal arch 4 gives rise to what cranial nerve branch? What is its function?

Answer 12

Superior laryngeal branch of vagus nerve
- Muscles of soft palate & pharynx

Question 13

Pharyngeal arch 5 gives rise to which cranial nerve branch? What is its function?

Answer 13

Recurrent laryngeal branch of vagus nerve
- Intrinsic laryngeal muscles & skeleton muscles of esophagus

Question 14

List the cranial nerves and their function (S, M, B)

Answer 14

CN I - Olfactory (S)
CN II - Optic (S)
CN III - Oculomotor (M)
CN IV - Trochlear (M)
CN V - Trigeminal (B)
CN VI - Abducens (M)
CN VII - Facial (B)
CN VIII - Vestibulocochlear (S)
CN IX - Glossopharyngeal (B)
CN X - Vagus (B)
CN XI - Accessory (M)
CN XII - Hypoglossal (M)

Question 15

Which of the cranial nerves have somatic efferent functions?

Answer 15

III oculomotor
IV trochlear
VI abducens
XI accessory
XII hypoglossal

Question 16

Which of the cranial nerves have somatic afferent functions?

Answer 16

V trigeminal
IX glossopharyngeal

Question 17

Which of the cranial nerves have autonomic efferent parasympathetic functions?

Answer 17

III oculomotor
VII facial
IX glossopharyngeal
X vagus

Question 18

Which of the cranial nerves have autonomic afferent parasympathetic functions?

Answer 18

X vagus

Question 19

Which of the cranial nerves are derived from brachial/pharyngeal archs and have special efferent function?

Answer 19

V trigeminal
VII facial
IX glossopharyngeal
X vagus

Question 20

Which of the cranial nerves have a special afferent function?

Answer 20

I olfactory
II optic
VII facial
VIII hypoglossal
IX glossopharyngeal
X vagus

Question 21

CN I - olfactory deals with what? Afferent or efferent?

Answer 21

Afferent smell

Question 22

CN II - optic deals with what? Afferent or efferent?

Answer 22

Afferent vision

Question 23

CN IV trochlear deals with what? Somatic or autonomic? Afferent or efferent?

Answer 23

Somatic efferent eye muscle

Question 24

CN VI abducens deals with what? Somatic or autonomic? Afferent or efferent?

Answer 24

Somatic efferent eye muscle

Question 25

CN VIII vestibulocochlear deals with what? Afferent or efferent?

Answer 25

Afferent hearing/balance

Question 26

CN XI accessory deals with what? Afferent or efferent?

Answer 26

Efferent neck muscle

Question 27

XII hypoglossal deals with what? Afferent or efferent?

Answer 27

Somatic efferent tongue muscle

Question 28

CN III oculomotor has how many different functions? What are they?

Answer 28

1) somatic efferent eye muscle 2) autonomic efferent (parasympathetic) ciliary body/iris muscles

Question 29

CN V trigeminal has how many different functions? What are they?

Answer 29

1) somatic afferent sensation of face 2) special efferent ear and jaw muscles

Question 30

CN VII facial has how many different functions? What are they?

Answer 30

1) autonomic efferent (parasympathetic) salivary, lacrimal glands 2) special afferent taste anterior ⅔ tongue 3) special efferent muscles of face and ear

Question 31

CN IX glossopharyngeal has how many different functions? What are they?

Answer 31

1) somatic afferent face, ear, palate, tongue sensation 2) autonomic efferent (parasympathetic) salivary and mucosal glands 3) special efferent stylopharyngeus muscle 4) special afferent taste posterior ⅓ tongue

Question 32

CN X vagus has how many different functions? What are they?

Answer 32

1) autonomic afferent pharynx, larynx, thorax, abdomen 2) autonomic efferent (parasympathetic) heart, vessels, trachea, esophagus, stomach & intestine 3) special efferent laryngeal, soft palate, pharyngeal muscles 4) special afferent taste pharynx

Question 33

Neuroepithelial olfactory cells send axons through the ______ of the ______ bone to synapse in the _______ ______ to the ________ ______

Answer 33

Cribiform plate, ethmoid, olfactory bulb, olfactory tract

Question 34

Damage to the optic nerve symptoms & their definitions (3)

Answer 34

Blurry vision Monocular loss (prechiasm) - one eye Homonymous hemianopia (postchiasm) - contralateral visual field Scotoma - blind spot

Question 35

Damage to CN I symptoms & their definition (2)

Answer 35

Anosmia - loss of smell Ageusia - loss of taste

Question 36

CN II has special receptors cells located where?

Answer 36

In the retina at the back of the eye

Question 37

CN III has its motor nucleus where?

Answer 37

Upper midbrain

Question 38

CN III controls most eye movements and ________ elevation

Answer 38

Eyelid

Question 39

CN III controls _______ constriction & _____ accommodation (_______)

Answer 39

pupil, lens, parasympathetic

Question 40

Damage to the oculomotor nerve symptoms & definitions

Answer 40

Strabismus – lazy eye Diplopia– double vision Ptosis– eye lid droop Diminished pupillary reflex (diminished ipsi response)

Question 41

CN IV has its motor nucleus where?

Answer 41

Midbrain

Question 42

CN IV innervates which eye muscle(s)?

Answer 42

Superior oblique eye muscles

Question 43

Damage to trochlear nerve symptoms & defintions

Answer 43

Diplopia - double vision Head tilt

Question 44

CN V has how many branches? What are they?

Answer 44

3 Ophthalmic, maxillary, mandibular

Question 45

The motor nucleus of the CN V is located where?

Answer 45

In the pons

Question 46

What are the sensory and motor functions of the trigeminal nerve?

Answer 46

Purpose: sensory – pain and touch from face, tongue, ear, inside of orbit, mouth and proprioception of jaw. This is the nerve the dentist numbs. Purpose: motor – Jaw, mastication eustachian tube

Question 47

Damage to the trigeminal nerve symptoms & defintions

Answer 47

Tic Douloureux/trigeminal neuralgia (pain spasms)

Question 48

CN VI has its motor nucleus where?

Answer 48

Tegmentum of the pons

Question 49

CN VI innervates what muscle(s)?

Answer 49

Lateral rectus muscles (sides of eyeball)

Question 50

CN VII has a parasympathetic efferent function on what?

Answer 50

Salivary and lacrimal gland and mucus of nose and palate

Question 51

CN VII has a special sensory function for what sense?

Answer 51

Taste - anterior 2/3 of the tongue

Question 52

CN VII has special efferent function for what?

Answer 52

muscles of facial expression (frontalis, orbicularis oculi, levator labii, levator anguli oris, mentalis, orbicularis oris, buccinator, platysma, stapedius, stylohyoid, posterior belly of diagastric (not all inclusive)

Question 53

Damage to facial nerve symptoms & definitions

Answer 53

Contralateral facial droop (Bell’s Palsy) Dry mouth and tearing Impairment of taste and hyperacusis (sounds seem very loud)

Question 54

CN VIII has a special sensory function for what two senses? Where are their cells?

Answer 54

Hearing & balance Hearing - cochlear branch - hair cells in cochlea Balance - vestibular branch - hair cells in semicircular canals

Question 55

Damage to vestibulocochlear nerve symptoms & definitions

Answer 55

Dizziness Nausea Nystagmus (involuntary rapid eye movements) Vertigo (room spinning) Hearing loss

Question 56

CN IX has general sensory function for what structures?

Answer 56

ear drum, EAC, tonsil, posterior 1/3 of tongue

Question 57

CN IX has special sensory function for what structure?

Answer 57

Taste posterior 1/3 of tongue

Question 58

CN IX has a special efferent function for what muscle? What action does this correspond what?

Answer 58

Stylopharyngeus muscle (swallowing)

Question 59

CN IX has a autonomic parasympathetic efferent function for what structure?

Answer 59

Parotid salivary gland

Question 60

Damage to glossopharyngeal nerve symptoms & definitions

Answer 60

Glossopharyngeal neuralgia (pain of a nerve) Allodynia (pain for a nonpainful stimulus) Some loss of taste or feeling in palate/pharynx, dry/wet mouth Difficulty swallowing

Question 61

CN X has a general sensory function for what structures

Answer 61

Mostly pharynx and larynx

Question 62

CN X has autonomic sensory function for what structures?

Answer 62

larynx, trachea, esophagus, guts, blood vessels

Question 63

The special efferent functions of the CN X are carried out by 3 branches. What are they and what muscles to they innervate?

Answer 63

1. Pharyngeal (muscles of resonance) 2. Superior Laryngeal and 3. Recurrent Laryngeal (muscles of phonation) Innervates the palatal muscles, swallowing muscles and voicing muscles

Question 64

CN X has autonomic/parasympathetic efferent motor functions for what structures?

Answer 64

Heart, lungs, intestines

Question 65

Damage to the vagus nerve symptoms & definitions

Answer 65

Dysphagia is difficulty swallowing Dysphonia refers to difficulty producing speech sounds due to issues with the voice box (larynx)

Question 66

CN XI has special efferent functions for what muscles?

Answer 66

sternocleidomastoid and trapezius muscle

Question 67

Damage to accessory nerve symptoms & definitions

Answer 67

Weakness in shoulder elevation Weakness in head rotation

Question 68

CN XII has somatic motor function with what structures?

Answer 68

Most extrinsic and intrinsic muscles of the tongue

Question 69

Damage to hypoglossal nerve symptoms & definitions

Answer 69

Tongue protrusion toward weak side Fasciculations - small, involuntary muscle contractions or twitches